diff --git a/.eslint/rules/file-suffix.js b/.eslint/rules/file-suffix.js
index 52d9da4f5b..954ba914ee 100644
--- a/.eslint/rules/file-suffix.js
+++ b/.eslint/rules/file-suffix.js
@@ -90,6 +90,7 @@ const NODE_PACKAGES = new Set([
   '@signalapp/mock-server',
   '@tailwindcss/cli',
   '@tailwindcss/postcss',
+  'better-blockmap',
   'chokidar-cli',
   'cross-env',
   'electron-builder',
diff --git a/app/main.main.ts b/app/main.main.ts
index 9fd3394614..34eb460a29 100644
--- a/app/main.main.ts
+++ b/app/main.main.ts
@@ -135,6 +135,7 @@ import { getOwn } from '../ts/util/getOwn.std.js';
 import { safeParseLoose, safeParseUnknown } from '../ts/util/schemas.std.js';
 import { getAppErrorIcon } from '../ts/util/getAppErrorIcon.node.js';
 import { promptOSAuth } from '../ts/util/os/promptOSAuthMain.main.js';
+import { appRelaunch } from '../ts/util/relaunch.main.js';
 import { sendDummyKeystroke } from './WindowsNotifications.main.js';
 
 const { chmod, realpath, writeFile } = fsExtra;
@@ -1935,7 +1936,7 @@ const onDatabaseInitializationError = async (error: Error) => {
       log.error(
         'onDatabaseInitializationError: Requesting immediate restart after quit'
       );
-      app.relaunch();
+      appRelaunch();
     }
   } else if (buttonIndex === goToSupportPageButtonIndex) {
     drop(
@@ -2343,6 +2344,11 @@ app.on('ready', async () => {
 
 function setupMenu(options?: Partial<CreateTemplateOptionsType>) {
   const { platform } = process;
+  const platformForMenu =
+    platform === 'linux' && process.env.APPIMAGE != null
+      ? 'linux-appimage'
+      : platform;
+
   const version = app.getVersion();
   menuOptions = {
     // options
@@ -2351,7 +2357,7 @@ function setupMenu(options?: Partial<CreateTemplateOptionsType>) {
     includeSetup: false,
     isNightly: isNightly(version),
     isProduction: isProduction(version),
-    platform,
+    platform: platformForMenu,
 
     // actions
     forceUpdate,
@@ -2630,7 +2636,7 @@ ipc.on('draw-attention', () => {
 
 ipc.on('restart', () => {
   log.info('Relaunching application');
-  app.relaunch();
+  appRelaunch();
   app.quit();
 });
 ipc.on('shutdown', () => {
diff --git a/config/default.json b/config/default.json
index cd64ea7fcc..3b7c3a117f 100644
--- a/config/default.json
+++ b/config/default.json
@@ -12,6 +12,7 @@
   "updatesUrl": "https://updates2.signal.org/desktop",
   "resourcesUrl": "https://updates2.signal.org",
   "updatesPublicKey": "05fd7dd3de7149dc0a127909fee7de0f7620ddd0de061b37a2c303e37de802a401",
+  "appImageUpdatesPublicKey": "05dc20ac83f663c517718b6057f2fe34e273b88455f2149513912f24a9a380cc63",
   "sfuUrl": "https://sfu.staging.voip.signal.org/",
   "challengeUrl": "https://signalcaptchas.org/staging/challenge/generate.html",
   "registrationChallengeUrl": "https://signalcaptchas.org/staging/registration/generate.html",
diff --git a/package.json b/package.json
index e34a6602bd..c980f1d657 100644
--- a/package.json
+++ b/package.json
@@ -301,6 +301,7 @@
     "babel-core": "7.0.0-bridge.0",
     "babel-loader": "9.2.1",
     "babel-plugin-lodash": "3.3.4",
+    "better-blockmap": "1.0.2",
     "casual": "1.6.2",
     "chai": "4.4.1",
     "chai-as-promised": "7.1.1",
@@ -526,11 +527,17 @@
           "StartupWMClass": "signal"
         }
       },
+      "artifactName": "${name}_${version}_${arch}.${ext}",
       "target": [
         "deb"
       ],
       "icon": "build/icons/png",
-      "publish": [],
+      "publish": [
+        {
+          "provider": "generic",
+          "url": ""
+        }
+      ],
       "extraResources": [
         {
           "from": "build",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index c6a5d08548..08a469624e 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -622,6 +622,9 @@ importers:
       babel-plugin-lodash:
         specifier: 3.3.4
         version: 3.3.4
+      better-blockmap:
+        specifier: 1.0.2
+        version: 1.0.2
       casual:
         specifier: 1.6.2
         version: 1.6.2(patch_hash=b88b5052437cbdc1882137778b76ca5037f71b2a030ae9ef39dc97f51670d599)
diff --git a/ts/scripts/artifact-build-completed.node.ts b/ts/scripts/artifact-build-completed.node.ts
index 2d92f382f8..d014a65895 100644
--- a/ts/scripts/artifact-build-completed.node.ts
+++ b/ts/scripts/artifact-build-completed.node.ts
@@ -2,12 +2,14 @@
 // SPDX-License-Identifier: AGPL-3.0-only
 
 import { tmpdir } from 'node:os';
-import { mkdtemp, rm, rename, stat } from 'node:fs/promises';
+
+import { mkdtemp, rm, rename, stat, writeFile } from 'node:fs/promises';
 import { createReadStream } from 'node:fs';
 import { pipeline } from 'node:stream/promises';
 import { createHash } from 'node:crypto';
 import path from 'node:path';
 import type { ArtifactCreated } from 'electron-builder';
+import { BlockMap } from 'better-blockmap';
 
 export async function artifactBuildCompleted({
   target,
@@ -15,6 +17,14 @@ export async function artifactBuildCompleted({
   packager,
   updateInfo,
 }: ArtifactCreated): Promise<void> {
+  if (packager.platform.name === 'linux' && file.endsWith('.AppImage')) {
+    const blockMapPath = `${file}.blockmap`;
+    console.log(`Generating blockmap ${blockMapPath}`);
+    const blockMapGenerator = new BlockMap({ detectZipBoundary: true });
+    await pipeline(createReadStream(file), blockMapGenerator);
+    await writeFile(blockMapPath, blockMapGenerator.compress());
+  }
+
   if (packager.platform.name !== 'mac') {
     return;
   }
diff --git a/ts/scripts/better-blockmap.d.ts b/ts/scripts/better-blockmap.d.ts
new file mode 100644
index 0000000000..2d4ac52926
--- /dev/null
+++ b/ts/scripts/better-blockmap.d.ts
@@ -0,0 +1,15 @@
+// Copyright 2025 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+declare module 'better-blockmap' {
+  import { Writable } from 'node:stream';
+
+  type BlockMapOptions = {
+    detectZipBoundary?: boolean;
+  };
+
+  export class BlockMap extends Writable {
+    constructor(options?: BlockMapOptions);
+    compress(compression?: 'gzip' | 'deflate'): Buffer;
+  }
+}
diff --git a/ts/types/Settings.std.ts b/ts/types/Settings.std.ts
index b57a4a7aae..9a5e528969 100644
--- a/ts/types/Settings.std.ts
+++ b/ts/types/Settings.std.ts
@@ -69,7 +69,7 @@ export const isAutoDownloadUpdatesSupported = (
   if (isNotUpdatable(appVersion)) {
     return false;
   }
-  return OS.isWindows() || OS.isMacOS();
+  return OS.isWindows() || OS.isMacOS() || OS.isLinuxAppImage();
 };
 
 export const shouldHideExpiringMessageBody = (
diff --git a/ts/updater/common.main.ts b/ts/updater/common.main.ts
index 0710e7e18b..b600022f64 100644
--- a/ts/updater/common.main.ts
+++ b/ts/updater/common.main.ts
@@ -282,6 +282,10 @@ export abstract class Updater {
     markShouldQuit();
   }
 
+  protected getUpdatesPublicKey(): Buffer {
+    return hexToBinary(config.get('updatesPublicKey'));
+  }
+
   //
   // Private methods
   //
@@ -390,12 +394,11 @@ export abstract class Updater {
 
       const { updateFilePath, signature } = downloadResult;
 
-      const publicKey = hexToBinary(config.get('updatesPublicKey'));
       const verified = await verifySignature(
         updateFilePath,
         this.version,
         signature,
-        publicKey
+        this.getUpdatesPublicKey()
       );
       if (!verified) {
         // Note: We don't delete the cache here, because we don't want to continually
@@ -989,6 +992,10 @@ export function getUpdatesFileName(): string {
     return `${prefix}-mac.yml`;
   }
 
+  if (process.platform === 'linux') {
+    return `${prefix}-linux.yml`;
+  }
+
   return `${prefix}.yml`;
 }
 
@@ -1020,7 +1027,7 @@ export function getVersion(info: JSONUpdateSchema): string | null {
   return info && info.version;
 }
 
-const validFile = /^[A-Za-z0-9.-]+$/;
+const validFile = /^[A-Za-z0-9._-]+$/;
 export function isUpdateFileNameValid(name: string): boolean {
   return validFile.test(name);
 }
@@ -1041,6 +1048,8 @@ export function getUpdateFileName(
     fileFilter = ({ url }) => url.includes(arch) && url.endsWith('.zip');
   } else if (platform === 'win32') {
     fileFilter = ({ url }) => url.includes(arch) && url.endsWith('.exe');
+  } else if (platform === 'linux' && process.env.APPIMAGE != null) {
+    fileFilter = ({ url }) => url.endsWith('.AppImage');
   }
 
   if (fileFilter) {
diff --git a/ts/updater/index.main.ts b/ts/updater/index.main.ts
index c08a91271f..5434d7129c 100644
--- a/ts/updater/index.main.ts
+++ b/ts/updater/index.main.ts
@@ -6,6 +6,7 @@ import { app } from 'electron';
 import type { Updater, UpdaterOptionsType } from './common.main.js';
 import { MacOSUpdater } from './macos.main.js';
 import { WindowsUpdater } from './windows.main.js';
+import { LinuxAppImageUpdater } from './linuxAppImage.main.js';
 import { initLinux } from './linux.main.js';
 
 let initialized = false;
@@ -38,7 +39,11 @@ export async function start(options: UpdaterOptionsType): Promise<void> {
   } else if (platform === 'darwin') {
     updater = new MacOSUpdater(options);
   } else if (platform === 'linux') {
-    initLinux(options);
+    if (process.env.APPIMAGE != null) {
+      updater = new LinuxAppImageUpdater(options);
+    } else {
+      initLinux(options);
+    }
   } else {
     throw new Error(`updater/start: Unsupported platform ${platform}`);
   }
diff --git a/ts/updater/linux.main.ts b/ts/updater/linux.main.ts
index d45643fa80..26fa6999db 100644
--- a/ts/updater/linux.main.ts
+++ b/ts/updater/linux.main.ts
@@ -13,6 +13,7 @@ import type { LoggerType } from '../types/Logging.std.js';
 import { DialogType } from '../types/Dialogs.std.js';
 import * as Errors from '../types/errors.std.js';
 import type { UpdaterOptionsType } from './common.main.js';
+import { appRelaunch } from '../util/relaunch.main.js';
 
 const MIN_UBUNTU_VERSION = '22.04';
 
@@ -60,7 +61,7 @@ export function initLinux({ logger, getMainWindow }: UpdaterOptionsType): void {
   ipcMain.handle('start-update', () => {
     logger?.info('updater/linux: restarting');
     markShouldQuit();
-    app.relaunch();
+    appRelaunch();
     app.quit();
   });
 
diff --git a/ts/updater/linuxAppImage.main.ts b/ts/updater/linuxAppImage.main.ts
new file mode 100644
index 0000000000..4ed8c8695e
--- /dev/null
+++ b/ts/updater/linuxAppImage.main.ts
@@ -0,0 +1,74 @@
+// Copyright 2025 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { copyFile, unlink } from 'node:fs/promises';
+import { chmod } from 'fs-extra';
+
+import config from 'config';
+import { app } from 'electron';
+
+import { Updater } from './common.main.js';
+import { appRelaunch } from '../util/relaunch.main.js';
+import { hexToBinary } from './signature.node.js';
+
+export class LinuxAppImageUpdater extends Updater {
+  #installing = false;
+
+  protected async deletePreviousInstallers(): Promise<void> {
+    // No installers are cached beyond the most recent one
+  }
+
+  protected async installUpdate(
+    updateFilePath: string
+  ): Promise<() => Promise<void>> {
+    const { logger } = this;
+
+    return async () => {
+      logger.info('downloadAndInstall: installing...');
+      try {
+        await this.#install(updateFilePath);
+        this.#installing = true;
+      } catch (error) {
+        this.markCannotUpdate(error);
+
+        throw error;
+      }
+
+      // If interrupted at this point, we only want to restart (not reattempt install)
+      this.setUpdateListener(this.restart);
+      this.restart();
+    };
+  }
+
+  protected restart(): void {
+    this.logger.info('downloadAndInstall: restarting...');
+
+    this.markRestarting();
+    appRelaunch();
+    app.quit();
+  }
+
+  override getUpdatesPublicKey(): Buffer {
+    return hexToBinary(config.get('appImageUpdatesPublicKey'));
+  }
+
+  async #install(updateFilePath: string): Promise<void> {
+    if (this.#installing) {
+      return;
+    }
+
+    const { logger } = this;
+
+    logger.info('linuxAppImage/install: installing package...');
+
+    const appImageFile = process.env.APPIMAGE;
+    if (appImageFile == null) {
+      throw new Error('APPIMAGE env is not defined!');
+    }
+
+    // https://stackoverflow.com/a/1712051/1910191
+    await unlink(appImageFile);
+    await copyFile(updateFilePath, appImageFile);
+    await chmod(appImageFile, 0o700);
+  }
+}
diff --git a/ts/util/os/osMain.node.ts b/ts/util/os/osMain.node.ts
index b29b2f2a48..7b6988530c 100644
--- a/ts/util/os/osMain.node.ts
+++ b/ts/util/os/osMain.node.ts
@@ -18,7 +18,17 @@ function getLinuxName(): string | undefined {
     return undefined;
   }
 
-  return match[1];
+  const name = match[1];
+  if (isAppImage()) {
+    return `${name} (AppImage)`;
+  }
+  // Flatpak is noted already in /etc/os-release
+
+  return name;
+}
+
+function isAppImage(): boolean {
+  return process.platform === 'linux' && process.env.APPIMAGE != null;
 }
 
 function isFlatpak(): boolean {
@@ -45,6 +55,7 @@ function isLinuxUsingKDE(): boolean {
 const OS = {
   ...getOSFunctions(os.release()),
   getLinuxName,
+  isAppImage,
   isFlatpak,
   isLinuxUsingKDE,
   isWaylandEnabled,
diff --git a/ts/util/os/shared.std.ts b/ts/util/os/shared.std.ts
index 7d2c06d684..09bc8f7c5f 100644
--- a/ts/util/os/shared.std.ts
+++ b/ts/util/os/shared.std.ts
@@ -23,6 +23,7 @@ export type OSType = {
   getClassName: () => string;
   getName: () => string;
   isLinux: (minVersion?: string) => boolean;
+  isLinuxAppImage: () => boolean;
   isMacOS: (minVersion?: string) => boolean;
   isWindows: (minVersion?: string) => boolean;
 };
@@ -32,6 +33,10 @@ export function getOSFunctions(osRelease: string): OSType {
   const isLinux = createIsPlatform('linux', osRelease);
   const isWindows = createIsPlatform('win32', osRelease);
 
+  const isLinuxAppImage = (): boolean => {
+    return process.platform === 'linux' && process.env.APPIMAGE != null;
+  };
+
   const getName = (): string => {
     if (isMacOS()) {
       return 'macOS';
@@ -56,6 +61,7 @@ export function getOSFunctions(osRelease: string): OSType {
     getClassName,
     getName,
     isLinux,
+    isLinuxAppImage,
     isMacOS,
     isWindows,
   };
diff --git a/ts/util/relaunch.main.ts b/ts/util/relaunch.main.ts
new file mode 100644
index 0000000000..a422162c2e
--- /dev/null
+++ b/ts/util/relaunch.main.ts
@@ -0,0 +1,21 @@
+// Copyright 2025 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { app } from 'electron';
+import type { RelaunchOptions } from 'electron';
+
+import OS from './os/osMain.node.js';
+
+// app.relaunch() doesn't work in AppImage, so this is a workaround
+export function appRelaunch(): void {
+  if (!OS.isAppImage()) {
+    app.relaunch();
+    return;
+  }
+
+  const options: RelaunchOptions = {
+    args: ['--appimage-extract-and-run', ...process.argv],
+    execPath: process.env.APPIMAGE,
+  };
+  app.relaunch(options);
+}