diff --git a/src/node/db/PadManager.ts b/src/node/db/PadManager.ts
index 4a447f850..c0c4b0f6a 100644
--- a/src/node/db/PadManager.ts
+++ b/src/node/db/PadManager.ts
@@ -105,7 +105,7 @@ const padList = new class {
  * @param {string} [authorId] - Optional author ID of the user that initiated the pad creation (if
  *     applicable).
  */
-exports.getPad = async (id: string, text: string, authorId:string = '') => {
+exports.getPad = async (id: string, text: string|null, authorId:string = '') => {
   // check if this is a valid padId
   if (!exports.isValidPadId(id)) {
     throw new CustomError(`${id} is not a valid padId`, 'apierror');
diff --git a/src/node/handler/APIHandler.js b/src/node/handler/APIHandler.ts
similarity index 91%
rename from src/node/handler/APIHandler.js
rename to src/node/handler/APIHandler.ts
index 3b5a3fb63..616d20675 100644
--- a/src/node/handler/APIHandler.js
+++ b/src/node/handler/APIHandler.ts
@@ -19,19 +19,21 @@
  * limitations under the License.
  */
 
+import {MapArrayType} from "../types/MapType";
+
 const absolutePaths = require('../utils/AbsolutePaths');
-const fs = require('fs');
+import fs from 'fs';
 const api = require('../db/API');
-const log4js = require('log4js');
+import log4js from 'log4js';
 const padManager = require('../db/PadManager');
 const randomString = require('../utils/randomstring');
 const argv = require('../utils/Cli').argv;
-const createHTTPError = require('http-errors');
+import createHTTPError from 'http-errors';
 
 const apiHandlerLogger = log4js.getLogger('APIHandler');
 
 // ensure we have an apikey
-let apikey = null;
+let apikey:string|null = null;
 const apikeyFilename = absolutePaths.makeAbsolute(argv.apikey || './APIKEY.txt');
 
 try {
@@ -41,11 +43,11 @@ try {
   apiHandlerLogger.info(
       `Api key file "${apikeyFilename}" not found.  Creating with random contents.`);
   apikey = randomString(32);
-  fs.writeFileSync(apikeyFilename, apikey, 'utf8');
+  fs.writeFileSync(apikeyFilename, apikey!, 'utf8');
 }
 
 // a list of all functions
-const version = {};
+const version:MapArrayType<any> = {};
 
 version['1'] = {
   createGroup: [],
@@ -163,6 +165,14 @@ exports.latestApiVersion = '1.3.0';
 // exports the versions so it can be used by the new Swagger endpoint
 exports.version = version;
 
+
+type APIFields = {
+  apikey: string;
+  api_key: string;
+  padID: string;
+  padName: string;
+}
+
 /**
  * Handles a HTTP API call
  * @param {String} apiVersion the version of the api
@@ -171,7 +181,7 @@ exports.version = version;
  * @req express request object
  * @res express response object
  */
-exports.handle = async function (apiVersion, functionName, fields) {
+exports.handle = async function (apiVersion: string, functionName: string, fields: APIFields) {
   // say goodbye if this is an unknown API version
   if (!(apiVersion in version)) {
     throw new createHTTPError.NotFound('no such api version');
@@ -185,7 +195,7 @@ exports.handle = async function (apiVersion, functionName, fields) {
   // check the api key!
   fields.apikey = fields.apikey || fields.api_key;
 
-  if (fields.apikey !== apikey.trim()) {
+  if (fields.apikey !== apikey!.trim()) {
     throw new createHTTPError.Unauthorized('no or wrong API Key');
   }
 
@@ -201,6 +211,7 @@ exports.handle = async function (apiVersion, functionName, fields) {
   }
 
   // put the function parameters in an array
+  // @ts-ignore
   const functionParams = version[apiVersion][functionName].map((field) => fields[field]);
 
   // call the api function
diff --git a/src/node/handler/ExportHandler.js b/src/node/handler/ExportHandler.ts
similarity index 96%
rename from src/node/handler/ExportHandler.js
rename to src/node/handler/ExportHandler.ts
index 250221d18..0bf57e2d1 100644
--- a/src/node/handler/ExportHandler.js
+++ b/src/node/handler/ExportHandler.ts
@@ -23,11 +23,11 @@
 const exporthtml = require('../utils/ExportHtml');
 const exporttxt = require('../utils/ExportTxt');
 const exportEtherpad = require('../utils/ExportEtherpad');
-const fs = require('fs');
+import fs from 'fs';
 const settings = require('../utils/Settings');
-const os = require('os');
+import os from 'os';
 const hooks = require('../../static/js/pluginfw/hooks');
-const util = require('util');
+import util from 'util';
 const { checkValidRev } = require('../utils/checkValidRev');
 
 const fsp_writeFile = util.promisify(fs.writeFile);
@@ -43,7 +43,7 @@ const tempDirectory = os.tmpdir();
  * @param {String} readOnlyId the read only id of the pad to export
  * @param {String} type the type to export
  */
-exports.doExport = async (req, res, padId, readOnlyId, type) => {
+exports.doExport = async (req: any, res: any, padId: string, readOnlyId: string, type:string) => {
   // avoid naming the read-only file as the original pad's id
   let fileName = readOnlyId ? readOnlyId : padId;
 
diff --git a/src/node/handler/ImportHandler.js b/src/node/handler/ImportHandler.ts
similarity index 93%
rename from src/node/handler/ImportHandler.js
rename to src/node/handler/ImportHandler.ts
index 35ceddfdd..330a2d6f9 100644
--- a/src/node/handler/ImportHandler.js
+++ b/src/node/handler/ImportHandler.ts
@@ -23,21 +23,22 @@
 
 const padManager = require('../db/PadManager');
 const padMessageHandler = require('./PadMessageHandler');
-const fs = require('fs').promises;
-const path = require('path');
+import {promises as fs} from 'fs';
+import path from 'path';
 const settings = require('../utils/Settings');
 const {Formidable} = require('formidable');
-const os = require('os');
+import os from 'os';
 const importHtml = require('../utils/ImportHtml');
 const importEtherpad = require('../utils/ImportEtherpad');
-const log4js = require('log4js');
+import log4js from 'log4js';
 const hooks = require('../../static/js/pluginfw/hooks.js');
 
 const logger = log4js.getLogger('ImportHandler');
 
 // `status` must be a string supported by `importErrorMessage()` in `src/static/js/pad_impexp.js`.
 class ImportError extends Error {
-  constructor(status, ...args) {
+  status: string;
+  constructor(status: string, ...args:any) {
     super(...args);
     if (Error.captureStackTrace) Error.captureStackTrace(this, ImportError);
     this.name = 'ImportError';
@@ -47,15 +48,15 @@ class ImportError extends Error {
   }
 }
 
-const rm = async (path) => {
+const rm = async (path: string) => {
   try {
     await fs.unlink(path);
-  } catch (err) {
+  } catch (err:any) {
     if (err.code !== 'ENOENT') throw err;
   }
 };
 
-let converter = null;
+let converter:any = null;
 let exportExtension = 'htm';
 
 // load abiword only if it is enabled and if soffice is disabled
@@ -78,7 +79,7 @@ const tmpDirectory = os.tmpdir();
  * @param {String} padId the pad id to export
  * @param {String} authorId the author id to use for the import
  */
-const doImport = async (req, res, padId, authorId) => {
+const doImport = async (req:any, res:any, padId:string, authorId:string) => {
   // pipe to a file
   // convert file to html via abiword or soffice
   // set html in the pad
@@ -98,7 +99,7 @@ const doImport = async (req, res, padId, authorId) => {
   let fields;
   try {
     [fields, files] = await form.parse(req);
-  } catch (err) {
+  } catch (err:any) {
     logger.warn(`Import failed due to form error: ${err.stack || err}`);
     if (err.code === Formidable.formidableErrors.biggerThanMaxFileSize) {
       throw new ImportError('maxFileSize');
@@ -136,7 +137,7 @@ const doImport = async (req, res, padId, authorId) => {
 
   const destFile = path.join(tmpDirectory, `etherpad_import_${randNum}.${exportExtension}`);
   const context = {srcFile, destFile, fileEnding, padId, ImportError};
-  const importHandledByPlugin = (await hooks.aCallAll('import', context)).some((x) => x);
+  const importHandledByPlugin = (await hooks.aCallAll('import', context)).some((x:string) => x);
   const fileIsEtherpad = (fileEnding === '.etherpad');
   const fileIsHTML = (fileEnding === '.html' || fileEnding === '.htm');
   const fileIsTXT = (fileEnding === '.txt');
@@ -169,7 +170,7 @@ const doImport = async (req, res, padId, authorId) => {
     } else {
       try {
         await converter.convertFile(srcFile, destFile, exportExtension);
-      } catch (err) {
+      } catch (err:any) {
         logger.warn(`Converting Error: ${err.stack || err}`);
         throw new ImportError('convertFailed');
       }
@@ -210,7 +211,7 @@ const doImport = async (req, res, padId, authorId) => {
     if (importHandledByPlugin || useConverter || fileIsHTML) {
       try {
         await importHtml.setPadHTML(pad, text, authorId);
-      } catch (err) {
+      } catch (err:any) {
         logger.warn(`Error importing, possibly caused by malformed HTML: ${err.stack || err}`);
       }
     } else {
@@ -245,14 +246,14 @@ const doImport = async (req, res, padId, authorId) => {
  * @param {String} authorId the author id to use for the import
  * @return {Promise<void>} a promise
  */
-exports.doImport = async (req, res, padId, authorId = '') => {
+exports.doImport = async (req:any, res:any, padId:string, authorId:string = '') => {
   let httpStatus = 200;
   let code = 0;
   let message = 'ok';
   let directDatabaseAccess;
   try {
     directDatabaseAccess = await doImport(req, res, padId, authorId);
-  } catch (err) {
+  } catch (err:any) {
     const known = err instanceof ImportError && err.status;
     if (!known) logger.error(`Internal error during import: ${err.stack || err}`);
     httpStatus = known ? 400 : 500;
diff --git a/src/node/handler/PadMessageHandler.js b/src/node/handler/PadMessageHandler.ts
similarity index 93%
rename from src/node/handler/PadMessageHandler.js
rename to src/node/handler/PadMessageHandler.ts
index 8b9d6e068..bbeef736a 100644
--- a/src/node/handler/PadMessageHandler.js
+++ b/src/node/handler/PadMessageHandler.ts
@@ -19,6 +19,8 @@
  * limitations under the License.
  */
 
+import {MapArrayType} from "../types/MapType";
+
 const AttributeMap = require('../../static/js/AttributeMap');
 const padManager = require('../db/PadManager');
 const Changeset = require('../../static/js/Changeset');
@@ -37,16 +39,19 @@ const accessLogger = log4js.getLogger('access');
 const hooks = require('../../static/js/pluginfw/hooks.js');
 const stats = require('../stats')
 const assert = require('assert').strict;
-const {RateLimiterMemory} = require('rate-limiter-flexible');
+import {RateLimiterMemory} from 'rate-limiter-flexible';
+import {ChangesetRequest, PadUserInfo, SocketClientRequest} from "../types/SocketClientRequest";
+import {APool, AText, PadAuthor, PadType} from "../types/PadType";
+import {ChangeSet} from "../types/ChangeSet";
 const webaccess = require('../hooks/express/webaccess');
 const { checkValidRev } = require('../utils/checkValidRev');
 
-let rateLimiter;
-let socketio = null;
+let rateLimiter:any;
+let socketio:any = null;
 
 hooks.deprecationNotices.clientReady = 'use the userJoin hook instead';
 
-const addContextToError = (err, pfx) => {
+const addContextToError = (err:any, pfx:string) => {
   const newErr = new Error(`${pfx}${err.message}`, {cause: err});
   if (Error.captureStackTrace) Error.captureStackTrace(newErr, addContextToError);
   // Check for https://github.com/tc39/proposal-error-cause support, available in Node.js >= v16.10.
@@ -80,7 +85,7 @@ exports.socketio = () => {
  *       - readonly: Whether the client has read-only access (true) or read/write access (false).
  *       - rev: The last revision that was sent to the client.
  */
-const sessioninfos = {};
+const sessioninfos:MapArrayType<any> = {};
 exports.sessioninfos = sessioninfos;
 
 stats.gauge('totalUsers', () => socketio ? socketio.sockets.size : 0);
@@ -97,11 +102,13 @@ stats.gauge('activePads', () => {
  * Processes one task at a time per channel.
  */
 class Channels {
+  private readonly _exec: (ch:any, task:any) => any;
+  private _promiseChains: Map<any, Promise<any>>;
   /**
    * @param {(ch, task) => any} [exec] - Task executor. If omitted, tasks are assumed to be
    *     functions that will be executed with the channel as the only argument.
    */
-  constructor(exec = (ch, task) => task(ch)) {
+  constructor(exec = (ch: string, task:any) => task(ch)) {
     this._exec = exec;
     this._promiseChains = new Map();
   }
@@ -114,7 +121,7 @@ class Channels {
    * @param {any} task - The task to give to the executor.
    * @returns {Promise<any>} The value returned by the executor.
    */
-  async enqueue(ch, task) {
+  async enqueue(ch:any, task:any): Promise<any> {
     const p = (this._promiseChains.get(ch) || Promise.resolve()).then(() => this._exec(ch, task));
     const pc = p
         .catch(() => {}) // Prevent rejections from halting the queue.
@@ -136,7 +143,7 @@ const padChannels = new Channels((ch, {socket, message}) => handleUserChanges(so
  * This Method is called by server.ts to tell the message handler on which socket it should send
  * @param socket_io The Socket
  */
-exports.setSocketIO = (socket_io) => {
+exports.setSocketIO = (socket_io:any) => {
   socketio = socket_io;
 };
 
@@ -144,7 +151,7 @@ exports.setSocketIO = (socket_io) => {
  * Handles the connection of a new user
  * @param socket the socket.io Socket object for the new connection from the client
  */
-exports.handleConnect = (socket) => {
+exports.handleConnect = (socket:any) => {
   stats.meter('connects').mark();
 
   // Initialize sessioninfos for this new session
@@ -154,7 +161,7 @@ exports.handleConnect = (socket) => {
 /**
  * Kicks all sessions from a pad
  */
-exports.kickSessionsFromPad = (padID) => {
+exports.kickSessionsFromPad = (padID: string) => {
   if (typeof socketio.sockets.clients !== 'object') return;
 
   // skip if there is nobody on this pad
@@ -168,13 +175,13 @@ exports.kickSessionsFromPad = (padID) => {
  * Handles the disconnection of a user
  * @param socket the socket.io Socket object for the client
  */
-exports.handleDisconnect = async (socket) => {
+exports.handleDisconnect = async (socket:any) => {
   stats.meter('disconnects').mark();
   const session = sessioninfos[socket.id];
   delete sessioninfos[socket.id];
   // session.padId can be nullish if the user disconnects before sending CLIENT_READY.
   if (!session || !session.author || !session.padId) return;
-  const {session: {user} = {}} = socket.client.request;
+  const {session: {user} = {}} = socket.client.request as SocketClientRequest;
   /* eslint-disable prefer-template -- it doesn't support breaking across multiple lines */
   accessLogger.info('[LEAVE]' +
                     ` pad:${session.padId}` +
@@ -206,7 +213,7 @@ exports.handleDisconnect = async (socket) => {
  * @param socket the socket.io Socket object for the client
  * @param message the message from the client
  */
-exports.handleMessage = async (socket, message) => {
+exports.handleMessage = async (socket:any, message:typeof ChatMessage) => {
   const env = process.env.NODE_ENV || 'development';
 
   if (env === 'production') {
@@ -263,7 +270,7 @@ exports.handleMessage = async (socket, message) => {
     throw new Error(`pre-CLIENT_READY message from IP ${ip}: ${msg}`);
   }
 
-  const {session: {user} = {}} = socket.client.request;
+  const {session: {user} = {}} = socket.client.request as SocketClientRequest;
   const {accessStatus, authorID} =
       await securityManager.checkAccess(auth.padID, auth.sessionID, auth.token, user);
   if (accessStatus !== 'grant') {
@@ -319,7 +326,7 @@ exports.handleMessage = async (socket, message) => {
   }
 
   // Call handleMessage hook. If a plugin returns null, the message will be dropped.
-  if ((await hooks.aCallAll('handleMessage', context)).some((m) => m == null)) {
+  if ((await hooks.aCallAll('handleMessage', context)).some((m: null|string) => m == null)) {
     return;
   }
 
@@ -376,7 +383,7 @@ exports.handleMessage = async (socket, message) => {
  * @param socket the socket.io Socket object for the client
  * @param message the message from the client
  */
-const handleSaveRevisionMessage = async (socket, message) => {
+const handleSaveRevisionMessage = async (socket:any, message: string) => {
   const {padId, author: authorId} = sessioninfos[socket.id];
   const pad = await padManager.getPad(padId, null, authorId);
   await pad.addSavedRevision(pad.head, authorId);
@@ -389,7 +396,7 @@ const handleSaveRevisionMessage = async (socket, message) => {
  * @param msg {Object} the message we're sending
  * @param sessionID {string} the socketIO session to which we're sending this message
  */
-exports.handleCustomObjectMessage = (msg, sessionID) => {
+exports.handleCustomObjectMessage = (msg: typeof ChatMessage, sessionID: string) => {
   if (msg.data.type === 'CUSTOM') {
     if (sessionID) {
       // a sessionID is targeted: directly to this sessionID
@@ -407,7 +414,7 @@ exports.handleCustomObjectMessage = (msg, sessionID) => {
  * @param padID {Pad} the pad to which we're sending this message
  * @param msgString {String} the message we're sending
  */
-exports.handleCustomMessage = (padID, msgString) => {
+exports.handleCustomMessage = (padID: string, msgString:string) => {
   const time = Date.now();
   const msg = {
     type: 'COLLABROOM',
@@ -424,7 +431,7 @@ exports.handleCustomMessage = (padID, msgString) => {
  * @param socket the socket.io Socket object for the client
  * @param message the message from the client
  */
-const handleChatMessage = async (socket, message) => {
+const handleChatMessage = async (socket:any, message: typeof ChatMessage) => {
   const chatMessage = ChatMessage.fromObject(message.data.message);
   const {padId, author: authorId} = sessioninfos[socket.id];
   // Don't trust the user-supplied values.
@@ -444,7 +451,7 @@ const handleChatMessage = async (socket, message) => {
  * @param {string} [padId] - The destination pad ID. Deprecated; pass a chat message
  *     object as the first argument and the destination pad ID as the second argument instead.
  */
-exports.sendChatMessageToPadClients = async (mt, puId, text = null, padId = null) => {
+exports.sendChatMessageToPadClients = async (mt: typeof ChatMessage|number, puId: string, text:string|null = null, padId:string|null = null) => {
   const message = mt instanceof ChatMessage ? mt : new ChatMessage(text, puId, mt);
   padId = mt instanceof ChatMessage ? puId : padId;
   const pad = await padManager.getPad(padId, null, message.authorId);
@@ -465,7 +472,7 @@ exports.sendChatMessageToPadClients = async (mt, puId, text = null, padId = null
  * @param socket the socket.io Socket object for the client
  * @param message the message from the client
  */
-const handleGetChatMessages = async (socket, {data: {start, end}}) => {
+const handleGetChatMessages = async (socket:any, {data: {start, end}}:any) => {
   if (!Number.isInteger(start)) throw new Error(`missing or invalid start: ${start}`);
   if (!Number.isInteger(end)) throw new Error(`missing or invalid end: ${end}`);
   const count = end - start;
@@ -491,7 +498,7 @@ const handleGetChatMessages = async (socket, {data: {start, end}}) => {
  * @param socket the socket.io Socket object for the client
  * @param message the message from the client
  */
-const handleSuggestUserName = (socket, message) => {
+const handleSuggestUserName = (socket:any, message: typeof ChatMessage) => {
   const {newName, unnamedId} = message.data.payload;
   if (newName == null) throw new Error('missing newName');
   if (unnamedId == null) throw new Error('missing unnamedId');
@@ -511,7 +518,7 @@ const handleSuggestUserName = (socket, message) => {
  * @param socket the socket.io Socket object for the client
  * @param message the message from the client
  */
-const handleUserInfoUpdate = async (socket, {data: {userInfo: {name, colorId}}}) => {
+const handleUserInfoUpdate = async (socket:any, {data: {userInfo: {name, colorId}}}: PadUserInfo) => {
   if (colorId == null) throw new Error('missing colorId');
   if (!name) name = null;
   const session = sessioninfos[socket.id];
@@ -559,7 +566,7 @@ const handleUserInfoUpdate = async (socket, {data: {userInfo: {name, colorId}}})
  * @param socket the socket.io Socket object for the client
  * @param message the message from the client
  */
-const handleUserChanges = async (socket, message) => {
+const handleUserChanges = async (socket:any, message: typeof ChatMessage) => {
   // This one's no longer pending, as we're gonna process it now
   stats.counter('pendingEdits').dec();
 
@@ -658,7 +665,7 @@ const handleUserChanges = async (socket, message) => {
     thisSession.rev = newRev;
     if (newRev !== r) thisSession.time = await pad.getRevisionDate(newRev);
     await exports.updatePadClients(pad);
-  } catch (err) {
+  } catch (err:any) {
     socket.emit('message', {disconnect: 'badChangeset'});
     stats.meter('failedChangesets').mark();
     messageLogger.warn(`Failed to apply USER_CHANGES from author ${thisSession.author} ` +
@@ -668,7 +675,7 @@ const handleUserChanges = async (socket, message) => {
   }
 };
 
-exports.updatePadClients = async (pad) => {
+exports.updatePadClients = async (pad: PadType) => {
   // skip this if no-one is on this pad
   const roomSockets = _getRoomSockets(pad.id);
   if (roomSockets.length === 0) return;
@@ -683,7 +690,7 @@ exports.updatePadClients = async (pad) => {
   // via async.forEach with sequential for() loop. There is no real
   // benefits of running this in parallel,
   // but benefit of reusing cached revision object is HUGE
-  const revCache = {};
+  const revCache:MapArrayType<any> = {};
 
   await Promise.all(roomSockets.map(async (socket) => {
     const sessioninfo = sessioninfos[socket.id];
@@ -717,7 +724,7 @@ exports.updatePadClients = async (pad) => {
       };
       try {
         socket.emit('message', msg);
-      } catch (err) {
+      } catch (err:any) {
         messageLogger.error(`Failed to notify user of new revision: ${err.stack || err}`);
         return;
       }
@@ -730,7 +737,7 @@ exports.updatePadClients = async (pad) => {
 /**
  * Copied from the Etherpad Source Code. Don't know what this method does excatly...
  */
-const _correctMarkersInPad = (atext, apool) => {
+const _correctMarkersInPad = (atext: AText, apool: APool) => {
   const text = atext.text;
 
   // collect char positions of line markers (e.g. bullets) in new atext
@@ -739,7 +746,7 @@ const _correctMarkersInPad = (atext, apool) => {
   let offset = 0;
   for (const op of Changeset.deserializeOps(atext.attribs)) {
     const attribs = AttributeMap.fromString(op.attribs, apool);
-    const hasMarker = AttributeManager.lineAttributes.some((a) => attribs.has(a));
+    const hasMarker = AttributeManager.lineAttributes.some((a: string) => attribs.has(a));
     if (hasMarker) {
       for (let i = 0; i < op.chars; i++) {
         if (offset > 0 && text.charAt(offset - 1) !== '\n') {
@@ -777,7 +784,7 @@ const _correctMarkersInPad = (atext, apool) => {
  * @param socket the socket.io Socket object for the client
  * @param message the message from the client
  */
-const handleClientReady = async (socket, message) => {
+const handleClientReady = async (socket:any, message: typeof ChatMessage) => {
   const sessionInfo = sessioninfos[socket.id];
   if (sessionInfo == null) throw new Error('client disconnected');
   assert(sessionInfo.author);
@@ -805,8 +812,11 @@ const handleClientReady = async (socket, message) => {
   const currentTime = await pad.getRevisionDate(pad.getHeadRevisionNumber());
 
   // get all author data out of the database (in parallel)
-  const historicalAuthorData = {};
-  await Promise.all(authors.map(async (authorId) => {
+  const historicalAuthorData:MapArrayType<{
+    name: string;
+    colorId: string;
+  }> = {};
+  await Promise.all(authors.map(async (authorId: string) => {
     const author = await authorManager.getAuthor(authorId);
     if (!author) {
       messageLogger.error(`There is no author for authorId: ${authorId}. ` +
@@ -837,7 +847,7 @@ const handleClientReady = async (socket, message) => {
     }
   }
 
-  const {session: {user} = {}} = socket.client.request;
+  const {session: {user} = {}} = socket.client.request as SocketClientRequest;
   /* eslint-disable prefer-template -- it doesn't support breaking across multiple lines */
   accessLogger.info(`[${pad.head > 0 ? 'ENTER' : 'CREATE'}]` +
                     ` pad:${sessionInfo.padId}` +
@@ -859,7 +869,7 @@ const handleClientReady = async (socket, message) => {
     // By using client revision,
     // this below code sends all the revisions missed during the client reconnect
     const revisionsNeeded = [];
-    const changesets = {};
+    const changesets:MapArrayType<any> = {};
 
     let startNum = message.client_rev + 1;
     let endNum = pad.getHeadRevisionNumber() + 1;
@@ -919,7 +929,7 @@ const handleClientReady = async (socket, message) => {
       const attribsForWire = Changeset.prepareForWire(atext.attribs, pad.pool);
       apool = attribsForWire.pool.toJsonable();
       atext.attribs = attribsForWire.translated;
-    } catch (e) {
+    } catch (e:any) {
       messageLogger.error(e.stack || e);
       socket.emit('message', {disconnect: 'corruptPad'}); // pull the brakes
       throw new Error('corrupt pad');
@@ -927,7 +937,7 @@ const handleClientReady = async (socket, message) => {
 
     // Warning: never ever send sessionInfo.padId to the client. If the client is read only you
     // would open a security hole 1 swedish mile wide...
-    const clientVars = {
+    const clientVars:MapArrayType<any> = {
       skinName: settings.skinName,
       skinVariants: settings.skinVariants,
       randomVersionString: settings.randomVersionString,
@@ -1078,7 +1088,7 @@ const handleClientReady = async (socket, message) => {
 /**
  * Handles a request for a rough changeset, the timeslider client needs it
  */
-const handleChangesetRequest = async (socket, {data: {granularity, start, requestID}}) => {
+const handleChangesetRequest = async (socket:any, {data: {granularity, start, requestID}}: ChangesetRequest) => {
   if (granularity == null) throw new Error('missing granularity');
   if (!Number.isInteger(granularity)) throw new Error('granularity is not an integer');
   if (start == null) throw new Error('missing start');
@@ -1090,7 +1100,7 @@ const handleChangesetRequest = async (socket, {data: {granularity, start, reques
   const headRev = pad.getHeadRevisionNumber();
   if (start > headRev)
     start = headRev;
-  const data = await getChangesetInfo(pad, start, end, granularity);
+  const data:MapArrayType<any> = await getChangesetInfo(pad, start, end, granularity);
   data.requestID = requestID;
   socket.emit('message', {type: 'CHANGESET_REQ', data});
 };
@@ -1099,7 +1109,7 @@ const handleChangesetRequest = async (socket, {data: {granularity, start, reques
  * Tries to rebuild the getChangestInfo function of the original Etherpad
  * https://github.com/ether/pad/blob/master/etherpad/src/etherpad/control/pad/pad_changeset_control.js#L144
  */
-const getChangesetInfo = async (pad, startNum, endNum, granularity) => {
+const getChangesetInfo = async (pad: PadType, startNum: number, endNum:number, granularity: number) => {
   const headRevision = pad.getHeadRevisionNumber();
 
   // calculate the last full endnum
@@ -1124,8 +1134,8 @@ const getChangesetInfo = async (pad, startNum, endNum, granularity) => {
   }
 
   // Get all needed db values in parallel.
-  const composedChangesets = {};
-  const revisionDate = [];
+  const composedChangesets:MapArrayType<any> = {};
+  const revisionDate:number[] = [];
   const [lines] = await Promise.all([
     getPadLines(pad, startNum - 1),
     // Get all needed composite Changesets.
@@ -1176,7 +1186,7 @@ const getChangesetInfo = async (pad, startNum, endNum, granularity) => {
  * Tries to rebuild the getPadLines function of the original Etherpad
  * https://github.com/ether/pad/blob/master/etherpad/src/etherpad/control/pad/pad_changeset_control.js#L263
  */
-const getPadLines = async (pad, revNum) => {
+const getPadLines = async (pad: PadType, revNum: number) => {
   // get the atext
   let atext;
 
@@ -1196,7 +1206,7 @@ const getPadLines = async (pad, revNum) => {
  * Tries to rebuild the composePadChangeset function of the original Etherpad
  * https://github.com/ether/pad/blob/master/etherpad/src/etherpad/control/pad/pad_changeset_control.js#L241
  */
-const composePadChangesets = async (pad, startNum, endNum) => {
+const composePadChangesets = async (pad: PadType, startNum: number, endNum: number) => {
   // fetch all changesets we need
   const headNum = pad.getHeadRevisionNumber();
   endNum = Math.min(endNum, headNum + 1);
@@ -1210,7 +1220,7 @@ const composePadChangesets = async (pad, startNum, endNum) => {
   }
 
   // get all changesets
-  const changesets = {};
+  const changesets:MapArrayType<ChangeSet> = {};
   await Promise.all(changesetsNeeded.map(
       (revNum) => pad.getRevisionChangeset(revNum)
           .then((changeset) => changesets[revNum] = changeset)));
@@ -1234,13 +1244,13 @@ const composePadChangesets = async (pad, startNum, endNum) => {
   }
 };
 
-const _getRoomSockets = (padID) => {
+const _getRoomSockets = (padID: string) => {
   const ns = socketio.sockets; // Default namespace.
   // We could call adapter.clients(), but that method is unnecessarily asynchronous. Replicate what
   // it does here, but synchronously to avoid a race condition. This code will have to change when
   // we update to socket.io v3.
   const room = ns.adapter.rooms?.get(padID);
-  
+
   if (!room) return [];
 
   return Array.from(room)
@@ -1251,15 +1261,15 @@ const _getRoomSockets = (padID) => {
 /**
  * Get the number of users in a pad
  */
-exports.padUsersCount = (padID) => ({
+exports.padUsersCount = (padID:string) => ({
   padUsersCount: _getRoomSockets(padID).length,
 });
 
 /**
  * Get the list of users in a pad
  */
-exports.padUsers = async (padID) => {
-  const padUsers = [];
+exports.padUsers = async (padID: string) => {
+  const padUsers:PadAuthor[] = [];
 
   // iterate over all clients (in parallel)
   await Promise.all(_getRoomSockets(padID).map(async (roomSocket) => {
diff --git a/src/node/handler/SocketIORouter.js b/src/node/handler/SocketIORouter.ts
similarity index 84%
rename from src/node/handler/SocketIORouter.js
rename to src/node/handler/SocketIORouter.ts
index e34a16603..482276834 100644
--- a/src/node/handler/SocketIORouter.js
+++ b/src/node/handler/SocketIORouter.ts
@@ -20,6 +20,8 @@
  * limitations under the License.
  */
 
+import {MapArrayType} from "../types/MapType";
+import {SocketModule} from "../types/SocketModule";
 const log4js = require('log4js');
 const settings = require('../utils/Settings');
 const stats = require('../../node/stats')
@@ -31,15 +33,15 @@ const logger = log4js.getLogger('socket.io');
  * key is the component name
  * value is the component module
  */
-const components = {};
+const components:MapArrayType<any> = {};
 
-let io;
+let io:any;
 
 /** adds a component
  * @param {string} moduleName
  * @param {Module} module
  */
-exports.addComponent = (moduleName, module) => {
+exports.addComponent = (moduleName: string, module: SocketModule) => {
   if (module == null) return exports.deleteComponent(moduleName);
   components[moduleName] = module;
   module.setSocketIO(io);
@@ -49,22 +51,22 @@ exports.addComponent = (moduleName, module) => {
  * removes a component
  * @param {Module} moduleName
  */
-exports.deleteComponent = (moduleName) => { delete components[moduleName]; };
+exports.deleteComponent = (moduleName: string) => { delete components[moduleName]; };
 
 /**
  * sets the socket.io and adds event functions for routing
  * @param {Object} _io the socket.io instance
  */
-exports.setSocketIO = (_io) => {
+exports.setSocketIO = (_io:any) => {
   io = _io;
 
-  io.sockets.on('connection', (socket) => {
+  io.sockets.on('connection', (socket:any) => {
     const ip = settings.disableIPlogging ? 'ANONYMOUS' : socket.request.ip;
     logger.debug(`${socket.id} connected from IP ${ip}`);
 
     // wrap the original send function to log the messages
     socket._send = socket.send;
-    socket.send = (message) => {
+    socket.send = (message: string) => {
       logger.debug(`to ${socket.id}: ${JSON.stringify(message)}`);
       socket._send(message);
     };
@@ -74,7 +76,7 @@ exports.setSocketIO = (_io) => {
       components[i].handleConnect(socket);
     }
 
-    socket.on('message', (message, ack = () => {}) => (async () => {
+    socket.on('message', (message: any, ack: any = () => {}) => (async () => {
       if (!message.component || !components[message.component]) {
         throw new Error(`unknown message component: ${message.component}`);
       }
@@ -88,7 +90,7 @@ exports.setSocketIO = (_io) => {
           ack({name: err.name, message: err.message}); // socket.io can't handle Error objects.
         }));
 
-    socket.on('disconnect', (reason) => {
+    socket.on('disconnect', (reason: string) => {
       logger.debug(`${socket.id} disconnected: ${reason}`);
       // store the lastDisconnect as a timestamp, this is useful if you want to know
       // when the last user disconnected.  If your activePads is 0 and totalUsers is 0
diff --git a/src/node/hooks/express/webaccess.js b/src/node/hooks/express/webaccess.ts
similarity index 87%
rename from src/node/hooks/express/webaccess.js
rename to src/node/hooks/express/webaccess.ts
index e0a5bd084..43bdea5fc 100644
--- a/src/node/hooks/express/webaccess.js
+++ b/src/node/hooks/express/webaccess.ts
@@ -1,7 +1,10 @@
 'use strict';
 
-const assert = require('assert').strict;
-const log4js = require('log4js');
+import {strict as assert} from "assert";
+import log4js from 'log4js';
+import {SocketClientRequest} from "../../types/SocketClientRequest";
+import {WebAccessTypes} from "../../types/WebAccessTypes";
+import {SettingsUser} from "../../types/SettingsUser";
 const httpLogger = log4js.getLogger('http');
 const settings = require('../../utils/Settings');
 const hooks = require('../../../static/js/pluginfw/hooks');
@@ -10,14 +13,15 @@ const readOnlyManager = require('../../db/ReadOnlyManager');
 hooks.deprecationNotices.authFailure = 'use the authnFailure and authzFailure hooks instead';
 
 // Promisified wrapper around hooks.aCallFirst.
-const aCallFirst = (hookName, context, pred = null) => new Promise((resolve, reject) => {
-  hooks.aCallFirst(hookName, context, (err, r) => err != null ? reject(err) : resolve(r), pred);
+const aCallFirst = (hookName: string, context:any, pred = null) => new Promise((resolve, reject) => {
+  hooks.aCallFirst(hookName, context, (err:any, r: unknown) => err != null ? reject(err) : resolve(r), pred);
 });
 
 const aCallFirst0 =
-    async (hookName, context, pred = null) => (await aCallFirst(hookName, context, pred))[0];
+    // @ts-ignore
+    async (hookName: string, context:any, pred = null) => (await aCallFirst(hookName, context, pred))[0];
 
-exports.normalizeAuthzLevel = (level) => {
+exports.normalizeAuthzLevel = (level: string|boolean) => {
   if (!level) return false;
   switch (level) {
     case true:
@@ -32,7 +36,7 @@ exports.normalizeAuthzLevel = (level) => {
   return false;
 };
 
-exports.userCanModify = (padId, req) => {
+exports.userCanModify = (padId: string, req: SocketClientRequest) => {
   if (readOnlyManager.isReadOnlyId(padId)) return false;
   if (!settings.requireAuthentication) return true;
   const {session: {user} = {}} = req;
@@ -45,7 +49,7 @@ exports.userCanModify = (padId, req) => {
 // Exported so that tests can set this to 0 to avoid unnecessary test slowness.
 exports.authnFailureDelayMs = 1000;
 
-const checkAccess = async (req, res, next) => {
+const checkAccess = async (req:any, res:any, next: Function) => {
   const requireAdmin = req.path.toLowerCase().startsWith('/admin');
 
   // ///////////////////////////////////////////////////////////////////////////////////////////////
@@ -54,9 +58,9 @@ const checkAccess = async (req, res, next) => {
   // use the preAuthzFailure hook to override the default 403 error.
   // ///////////////////////////////////////////////////////////////////////////////////////////////
 
-  let results;
+  let results: null|boolean[];
   let skip = false;
-  const preAuthorizeNext = (...args) => { skip = true; next(...args); };
+  const preAuthorizeNext = (...args:any) => { skip = true; next(...args); };
   try {
     results = await aCallFirst('preAuthorize', {req, res, next: preAuthorizeNext},
         // This predicate will cause aCallFirst to call the hook functions one at a time until one
@@ -64,8 +68,9 @@ const checkAccess = async (req, res, next) => {
         // page, truthy entries are filtered out before checking to see whether the list is empty.
         // This prevents plugin authors from accidentally granting admin privileges to the general
         // public.
-        (r) => (skip || (r != null && r.filter((x) => (!requireAdmin || !x)).length > 0)));
-  } catch (err) {
+        // @ts-ignore
+        (r) => (skip || (r != null && r.filter((x) => (!requireAdmin || !x)).length > 0))) as boolean[];
+  } catch (err:any) {
     httpLogger.error(`Error in preAuthorize hook: ${err.stack || err.toString()}`);
     if (!skip) res.status(500).send('Internal Server Error');
     return;
@@ -87,7 +92,7 @@ const checkAccess = async (req, res, next) => {
   // This helper is used in steps 2 and 4 below, so it may be called twice per access: once before
   // authentication is checked and once after (if settings.requireAuthorization is true).
   const authorize = async () => {
-    const grant = async (level) => {
+    const grant = async (level: string|false) => {
       level = exports.normalizeAuthzLevel(level);
       if (!level) return false;
       const user = req.session.user;
@@ -132,7 +137,7 @@ const checkAccess = async (req, res, next) => {
   // ///////////////////////////////////////////////////////////////////////////////////////////////
 
   if (settings.users == null) settings.users = {};
-  const ctx = {req, res, users: settings.users, next};
+  const ctx:WebAccessTypes = {req, res, users: settings.users, next};
   // If the HTTP basic auth header is present, extract the username and password so it can be given
   // to authn plugins.
   const httpBasicAuth = req.headers.authorization && req.headers.authorization.startsWith('Basic ');
@@ -148,7 +153,8 @@ const checkAccess = async (req, res, next) => {
   }
   if (!(await aCallFirst0('authenticate', ctx))) {
     // Fall back to HTTP basic auth.
-    const {[ctx.username]: {password} = {}} = settings.users;
+    // @ts-ignore
+    const {[ctx.username]: {password} = {}} = settings.users as SettingsUser;
 
     if (!httpBasicAuth ||
         !ctx.username ||
@@ -193,6 +199,6 @@ const checkAccess = async (req, res, next) => {
  * Express middleware to authenticate the user and check authorization. Must be installed after the
  * express-session middleware.
  */
-exports.checkAccess = (req, res, next) => {
+exports.checkAccess = (req:any, res:any, next:Function) => {
   checkAccess(req, res, next).catch((err) => next(err || new Error(err)));
 };
diff --git a/src/node/types/APIHandlerType.ts b/src/node/types/APIHandlerType.ts
new file mode 100644
index 000000000..e69de29bb
diff --git a/src/node/types/ChangeSet.ts b/src/node/types/ChangeSet.ts
new file mode 100644
index 000000000..17f38f101
--- /dev/null
+++ b/src/node/types/ChangeSet.ts
@@ -0,0 +1,3 @@
+export type ChangeSet = {
+
+}
diff --git a/src/node/types/PadType.ts b/src/node/types/PadType.ts
index 5f222c969..b344ed8c5 100644
--- a/src/node/types/PadType.ts
+++ b/src/node/types/PadType.ts
@@ -13,8 +13,12 @@ export type PadType = {
     getAllAuthorColors: ()=>Promise<MapArrayType<string>>,
     remove: ()=>Promise<void>,
     text: ()=>string,
-    setText: (text: string)=>Promise<void>,
+    setText: (text: string, authorId?: string)=>Promise<void>,
     appendText: (text: string)=>Promise<void>,
+    getHeadRevisionNumber: ()=>number,
+    getRevisionDate: (rev: number)=>Promise<number>,
+    getRevisionChangeset: (rev: number)=>Promise<AChangeSet>,
+    appendRevision: (changeset: AChangeSet, author: string)=>Promise<void>,
 }
 
 
diff --git a/src/node/types/SocketAcknowledge.ts b/src/node/types/SocketAcknowledge.ts
new file mode 100644
index 000000000..a55f77219
--- /dev/null
+++ b/src/node/types/SocketAcknowledge.ts
@@ -0,0 +1,3 @@
+export type SocketAcknowledge = {
+
+}
diff --git a/src/node/types/SocketClientRequest.ts b/src/node/types/SocketClientRequest.ts
new file mode 100644
index 000000000..07c015fc5
--- /dev/null
+++ b/src/node/types/SocketClientRequest.ts
@@ -0,0 +1,30 @@
+export type SocketClientRequest = {
+    session: {
+        user: {
+            username: string;
+            readOnly: boolean;
+            padAuthorizations: {
+                [key: string]: string;
+            }
+        }
+    }
+}
+
+
+export type PadUserInfo = {
+    data: {
+        userInfo: {
+            name: string|null;
+            colorId: string;
+        }
+    }
+}
+
+
+export type ChangesetRequest = {
+    data: {
+        granularity: number;
+        start: number;
+        requestID: string;
+    }
+}
diff --git a/src/node/types/SocketModule.ts b/src/node/types/SocketModule.ts
new file mode 100644
index 000000000..fab6b572e
--- /dev/null
+++ b/src/node/types/SocketModule.ts
@@ -0,0 +1,3 @@
+export type SocketModule = {
+    setSocketIO: (io: any) => void;
+}
diff --git a/src/node/types/WebAccessTypes.ts b/src/node/types/WebAccessTypes.ts
new file mode 100644
index 000000000..b351f059f
--- /dev/null
+++ b/src/node/types/WebAccessTypes.ts
@@ -0,0 +1,10 @@
+import {SettingsUser} from "./SettingsUser";
+
+export type WebAccessTypes = {
+    username?: string|null;
+    password?: string;
+    req:any;
+    res:any;
+    next:any;
+    users: SettingsUser;
+}
diff --git a/src/node/utils/ImportEtherpad.js b/src/node/utils/ImportEtherpad.ts
similarity index 88%
rename from src/node/utils/ImportEtherpad.js
rename to src/node/utils/ImportEtherpad.ts
index da7e750ff..50b9a43d5 100644
--- a/src/node/utils/ImportEtherpad.js
+++ b/src/node/utils/ImportEtherpad.ts
@@ -1,5 +1,7 @@
 'use strict';
 
+import {APool} from "../types/PadType";
+
 /**
  * 2014 John McLear (Etherpad Foundation / McLear Ltd)
  *
@@ -22,17 +24,17 @@ const Stream = require('./Stream');
 const authorManager = require('../db/AuthorManager');
 const db = require('../db/DB');
 const hooks = require('../../static/js/pluginfw/hooks');
-const log4js = require('log4js');
+import log4js from 'log4js';
 const supportedElems = require('../../static/js/contentcollector').supportedElems;
-const ueberdb = require('ueberdb2');
+import ueberdb from 'ueberdb2';
 
 const logger = log4js.getLogger('ImportEtherpad');
 
-exports.setPadRaw = async (padId, r, authorId = '') => {
+exports.setPadRaw = async (padId: string, r: string, authorId = '') => {
   const records = JSON.parse(r);
 
   // get supported block Elements from plugins, we will use this later.
-  hooks.callAll('ccRegisterBlockElements').forEach((element) => {
+  hooks.callAll('ccRegisterBlockElements').forEach((element:any) => {
     supportedElems.add(element);
   });
 
@@ -43,8 +45,8 @@ exports.setPadRaw = async (padId, r, authorId = '') => {
     'pad',
   ];
 
-  let originalPadId = null;
-  const checkOriginalPadId = (padId) => {
+  let originalPadId:string|null = null;
+  const checkOriginalPadId = (padId: string) => {
     if (originalPadId == null) originalPadId = padId;
     if (originalPadId !== padId) throw new Error('unexpected pad ID in record');
   };
@@ -57,7 +59,10 @@ exports.setPadRaw = async (padId, r, authorId = '') => {
   const padDb = new ueberdb.Database('memory', {data});
   await padDb.init();
   try {
-    const processRecord = async (key, value) => {
+    const processRecord = async (key:string, value: null|{
+      padIDs: string|Record<string, unknown>,
+      pool: APool
+    }) => {
       if (!value) return;
       const keyParts = key.split(':');
       const [prefix, id] = keyParts;
@@ -79,7 +84,7 @@ exports.setPadRaw = async (padId, r, authorId = '') => {
         if (prefix === 'pad' && keyParts.length === 2) {
           const pool = new AttributePool().fromJsonable(value.pool);
           const unsupportedElements = new Set();
-          pool.eachAttrib((k, v) => {
+          pool.eachAttrib((k: string, v:any) => {
             if (!supportedElems.has(k)) unsupportedElements.add(k);
           });
           if (unsupportedElements.size) {
@@ -94,8 +99,10 @@ exports.setPadRaw = async (padId, r, authorId = '') => {
                      `importEtherpad hook function processes it: ${key}`);
         return;
       }
+      // @ts-ignore
       await padDb.set(key, value);
     };
+    // @ts-ignore
     const readOps = new Stream(Object.entries(records)).map(([k, v]) => processRecord(k, v));
     for (const op of readOps.batch(100).buffer(99)) await op;
 
diff --git a/src/node/utils/ImportHtml.js b/src/node/utils/ImportHtml.ts
similarity index 93%
rename from src/node/utils/ImportHtml.js
rename to src/node/utils/ImportHtml.ts
index d7b2172b0..57d9cbe4f 100644
--- a/src/node/utils/ImportHtml.js
+++ b/src/node/utils/ImportHtml.ts
@@ -15,15 +15,16 @@
  * limitations under the License.
  */
 
-const log4js = require('log4js');
+import log4js from 'log4js';
 const Changeset = require('../../static/js/Changeset');
 const contentcollector = require('../../static/js/contentcollector');
-const jsdom = require('jsdom');
+import jsdom from 'jsdom';
+import {PadType} from "../types/PadType";
 
 const apiLogger = log4js.getLogger('ImportHtml');
-let processor;
+let processor:any;
 
-exports.setPadHTML = async (pad, html, authorId = '') => {
+exports.setPadHTML = async (pad: PadType, html:string, authorId = '') => {
   if (processor == null) {
     const [{rehype}, {default: minifyWhitespace}] =
         await Promise.all([import('rehype'), import('rehype-minify-whitespace')]);
@@ -46,7 +47,7 @@ exports.setPadHTML = async (pad, html, authorId = '') => {
   try {
     // we use a try here because if the HTML is bad it will blow up
     cc.collectContent(document.body);
-  } catch (err) {
+  } catch (err: any) {
     apiLogger.warn(`Error processing HTML: ${err.stack || err}`);
     throw err;
   }
diff --git a/src/package.json b/src/package.json
index 31b2906b6..f23f716e0 100644
--- a/src/package.json
+++ b/src/package.json
@@ -81,6 +81,8 @@
   "devDependencies": {
     "@types/async": "^3.2.24",
     "@types/express": "^4.17.21",
+    "@types/http-errors": "^2.0.4",
+    "@types/jsdom": "^21.1.6",
     "@types/mocha": "^10.0.6",
     "@types/node": "^20.11.19",
     "@types/sinon": "^17.0.3",
diff --git a/src/tsconfig.json b/src/tsconfig.json
index eea5f16fa..179aae429 100644
--- a/src/tsconfig.json
+++ b/src/tsconfig.json
@@ -2,7 +2,7 @@
   "compilerOptions": {
     /* Visit https://aka.ms/tsconfig to read more about this file */
     "moduleDetection": "force",
-    "lib": ["es6"],
+    "lib": ["ES2023"],
     /* Language and Environment */
     "target": "es6",                                  /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
     /* Modules */