diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index ba14125f..03235212 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -91,6 +91,18 @@ Run the app:
 npm start
 ```
 
+The [debug](https://www.npmjs.com/package/debug) package is used for some general logging. If you want to see its output, you need to set the `DEBUG` environment variable.
+
+```sh
+DEBUG=* npm start
+```
+
+In PowerShell you need to write this instead:
+
+```sh
+$env:DEBUG='*'; npm start
+```
+
 ### Miscellaneous
 
 Lint all project TS files using ESLint.
diff --git a/src/database/index.ts b/src/database/index.ts
index 96848eba..ef64cdb8 100644
--- a/src/database/index.ts
+++ b/src/database/index.ts
@@ -1,13 +1,18 @@
+import Debug from "debug"
 import { dirname, join } from "node:path"
 import { parentPort } from "node:process"
 import { fileURLToPath } from "node:url"
 import { getAllValidData } from "optolith-database-schema"
 import { getAbsoluteEntityPaths } from "./contents/src/config.js"
+const debug = Debug("util:database")
 
 const root = join(dirname(fileURLToPath(import.meta.url)), "contents")
 
+debug("loading database ...")
+
 getAllValidData(getAbsoluteEntityPaths(root))
   .then(database => {
+    debug("database loaded")
     parentPort.postMessage(database)
   })
   .catch(() => {})
diff --git a/src/main/index.ts b/src/main/index.ts
index 3adb1f4c..799c667a 100644
--- a/src/main/index.ts
+++ b/src/main/index.ts
@@ -1,50 +1,49 @@
+import Debug from "debug"
 import { app, ipcMain, utilityProcess } from "electron"
-import { REACT_DEVELOPER_TOOLS, REDUX_DEVTOOLS, installExtension } from "electron-extension-installer"
 import { autoUpdater } from "electron-updater"
 import { readFile } from "node:fs/promises"
 import { join } from "node:path"
-import * as process from "node:process"
 import type { Database } from "../database/index.ts"
 import { createMainWindow, showMainWindow } from "./mainWindow.ts"
 import { ensureUserDataPathExists } from "./saveData.ts"
 import { checkForUpdatesOnRequest, checkForUpdatesOnStartup } from "./updater.ts"
+const debug = Debug("main")
 
 app.setAppUserModelId("lukasobermann.optolith")
 
-console.log("main: loading database ...")
+debug("loading database ...")
 const databaseProcess = utilityProcess.fork(join(__dirname, "./database.js"))
 const databaseLoading = new Promise<Database>(resolve => {
   databaseProcess.on("message", (message: Database) => {
-    console.log("main: database loaded")
+    debug("database received")
     resolve(message)
   })
 })
 
-console.log(process.platform)
-
 const runAsync = (fn: () => Promise<void>) => () => {
-  fn().catch(err => console.error("main: unexpected error", err))
+  fn().catch(err => debug("unexpected error: %O", err))
 }
 
 const setUserDataPath = async () => {
-  console.log("main: set user data path ...")
+  debug("setting user data path ...")
   app.setPath("userData", await ensureUserDataPathExists())
 }
 
 const installExtensions = async () => {
-  console.log("main: install extensions ...")
+  debug("install extensions ...")
 
-  const installedExtensions = await installExtension([
-    REACT_DEVELOPER_TOOLS,
-    REDUX_DEVTOOLS,
-  ])
+  const installedExtensions: string[] | string | undefined =
+    await Promise.resolve(undefined as string[] | string | undefined) /* await installExtension([
+      REACT_DEVELOPER_TOOLS,
+      REDUX_DEVTOOLS,
+    ]) */
 
   const installedExtensionsString =
     Array.isArray(installedExtensions)
       ? installedExtensions.join(", ")
-      : installedExtensions
+      : installedExtensions ?? "none"
 
-  console.log(`main: installed extensions: ${installedExtensionsString}`)
+  debug("installed extensions: %s", installedExtensionsString)
 }
 
 const readFileInAppPath = (...path: string[]) => readFile(join(app.getAppPath(), ...path), "utf-8")
@@ -64,7 +63,7 @@ app.whenReady().then(async () => {
   })
 
   const installUpdateInsteadOfStartup = await checkForUpdatesOnStartup()
-  console.log("main: install update instead of startup", installUpdateInsteadOfStartup)
+  debug("skip startup because of update?", installUpdateInsteadOfStartup ? "yes" : "no")
   if (!installUpdateInsteadOfStartup) {
     await setUserDataPath()
     await installExtensions()
diff --git a/src/main/mainWindow.ts b/src/main/mainWindow.ts
index fc382d3b..70464d8a 100644
--- a/src/main/mainWindow.ts
+++ b/src/main/mainWindow.ts
@@ -1,20 +1,22 @@
+import Debug from "debug"
 import { BrowserWindow, app, ipcMain, shell } from "electron"
 import windowStateKeeper from "electron-window-state"
 import * as path from "node:path"
 import * as url from "node:url"
 import type { Database } from "../database/index.ts"
+const debug = Debug("main:main")
 
 export const createMainWindow = async () => {
-  console.log("main: Create Window ...")
+  debug("Create Window ...")
 
-  console.log("main (window): Initialize window state keeper")
+  debug("Initialize window state keeper")
   const mainWindowState = windowStateKeeper({
     defaultHeight: 720,
     defaultWidth: 1280,
     file: "window.json",
   })
 
-  console.log("main (window): Initialize browser window")
+  debug("Initialize browser window")
   const mainWindow = new BrowserWindow({
     x: mainWindowState.x,
     y: mainWindowState.y,
@@ -38,24 +40,24 @@ export const createMainWindow = async () => {
 
   mainWindow.webContents.setWindowOpenHandler(details => {
     shell.openExternal(details.url)
-      .catch(console.error)
+      .catch(err => debug("unexpected error: %O", err))
     return { action: "deny" }
   })
 
-  console.log("main (window): Manage browser window with state keeper")
+  debug("Manage browser window with state keeper")
   mainWindowState.manage(mainWindow)
 
-  console.log("main (window): Load url")
+  debug("Load url")
   await mainWindow.loadURL(url.format({
     pathname: path.join(__dirname, "renderer_main.html"),
     protocol: "file:",
     slashes: true,
   }))
 
-  mainWindow.webContents.openDevTools()
+  // mainWindow.webContents.openDevTools()
 
   if (mainWindowState.isMaximized) {
-    console.log("main (window): Maximize window ...")
+    debug("Maximize window ...")
     mainWindow.maximize()
   }
 
@@ -89,6 +91,6 @@ export const createMainWindow = async () => {
 
 export const showMainWindow = (mainWindow: BrowserWindow, database: Database) => {
   mainWindow.webContents.send("database-available", database)
-  console.log("main (window): Show window once database is available")
+  debug("Show window once database is available")
   mainWindow.show()
 }
diff --git a/src/main/updater.ts b/src/main/updater.ts
index e9ee8d40..d10e9bb3 100644
--- a/src/main/updater.ts
+++ b/src/main/updater.ts
@@ -1,8 +1,10 @@
+import Debug from "debug"
 import { BrowserWindow, ipcMain } from "electron"
 import { CancellationToken, UpdateCheckResult, autoUpdater } from "electron-updater"
 import * as path from "node:path"
 import * as url from "node:url"
 import appIconMacOS from "../assets/icon/AppIcon.icns"
+const debug = Debug("main:updater")
 
 type AvailableUpdateCheckResult = {
   cancellationToken: CancellationToken
@@ -24,6 +26,7 @@ const checkForUpdates = async (): Promise<AvailableUpdateCheckResult | undefined
 }
 
 const createUpdaterWindow = async () => {
+  debug("create window")
   const updaterWindow = new BrowserWindow({
     icon: appIconMacOS,
     center: true,
@@ -46,7 +49,7 @@ const createUpdaterWindow = async () => {
   updaterWindow.webContents.openDevTools()
 
   autoUpdater.on("error", (err: Error) => {
-    console.log("updater: error", err)
+    debug("error %O", err)
     updaterWindow.webContents.send("auto-updater-error", err)
   })
 
@@ -73,47 +76,47 @@ const prepareUpdaterWindowForAvailableUpdate = (
   updaterWindow.webContents.send("update-available", updateInfo)
 
   autoUpdater.signals.progress(progressObj => {
-    console.log(`updater: download progress at ${progressObj.percent} %`)
+    debug("download progress at %d %", progressObj.percent)
     updaterWindow.webContents.send("download-progress", progressObj)
   })
 
   autoUpdater.signals.updateDownloaded(info => {
-    console.log(`updater: update downloaded to "${info.downloadedFile}"`)
+    debug("update downloaded to %s", info.downloadedFile)
     updaterWindow.webContents.send("update-downloaded", info)
   })
 
   ipcMain.on("download-update-later", () => {
-    console.log(`updater: download update later`)
+    debug("download update later")
     onCancelUpdate?.()
     updaterWindow.close()
   })
 
   ipcMain.on("download-update", () => {
-    console.log(`updater: downloading update ...`)
+    debug("downloading update ...")
     autoUpdater.downloadUpdate(cancellationToken).catch(console.error)
   })
 
   ipcMain.on("install-update-later", () => {
-    console.log(`updater: install update later`)
+    debug("install update later")
     onCancelUpdate?.()
     updaterWindow.close()
   })
 
   ipcMain.on("quit-and-install-update", () => {
-    console.log(`updater: quit and install update`)
+    debug("quit and install update")
     onApplyUpdate?.()
     autoUpdater.quitAndInstall()
   })
 }
 
 export const checkForUpdatesOnStartup = async () => {
-  console.log("updater: checking for updates ...")
+  debug("checking for updates ...")
 
   const checkResult = await checkForUpdates()
   const isUpdateAvailable = checkResult !== undefined
 
   if (isUpdateAvailable) {
-    console.log("updater: update is available")
+    debug("update is available")
     const updaterWindow = await createUpdaterWindow()
     const updatePromise = new Promise<boolean>(resolve => {
       prepareUpdaterWindowForAvailableUpdate(
@@ -127,24 +130,24 @@ export const checkForUpdatesOnStartup = async () => {
     return updatePromise
   }
   else {
-    console.log("updater: no update available")
+    debug("no update available")
     return false
   }
 }
 
 export const checkForUpdatesOnRequest = async () => {
-  console.log("updater: checking for updates ...")
+  debug("checking for updates ...")
   const updaterWindow = await createUpdaterWindow()
   updaterWindow.show()
   const checkResult = await checkForUpdates()
   const isUpdateAvailable = checkResult !== undefined
 
   if (isUpdateAvailable) {
-    console.log("updater: update is available")
+    debug("update is available")
     prepareUpdaterWindowForAvailableUpdate(updaterWindow, checkResult)
   }
   else {
-    console.log("updater: no update available")
+    debug("no update available")
     updaterWindow.webContents.send("no-update-available")
   }