Librething

Turn an old Android (Android 7.0 or newer) phone or tablet into a Spotify Connect receiver — the kind that shows up right inside the Spotify app as a device you can send music to, no cable or pairing required.

Librething runs the real Spotify Connect protocol on the device itself. Once it's set up, you just open Spotify on your phone or laptop, tap the Connect icon, pick the device, and your music starts playing through whatever speaker or headphones are plugged into it — even after you close Spotify on your other device. It keeps running in the background like a dedicated speaker would.

What it can do

• Works like a real Spotify Connect device — appears automatically to any Spotify app on the same Wi-Fi network, or you can sign in directly to use it in a different network.
• Runs in the background, even with the screen off, so the device can sit in a corner like an actual speaker. (which is exactly how I use my own setup)
• Material Express style player - transfer your phone into a Car thing like device.
• Gesture controls (optional) — double-tap the cover art to play/pause, swipe to skip tracks or adjust volume, with adjustable haptic feedback. Can be scoped to just the cover art or expanded to the whole screen, and works the same way while fake-sleeping.
• Fake sleep — dims the screen to pure black while still playing, to protect OLED screens from burn-in and stop the display from being a distraction. Fades to black automatically after a period of inactivity, or trigger it yourself with one tap.
• OLED protection (optional) — for when the dashboard just sits there for hours: nudge everything on screen by a few pixels once a minute, or dim the screen by blacking out alternating pixels in a checkerboard, so nothing stays lit in the exact same spot the whole time.
• Display filters (optional) — schedule a grayscale or red-light-only mode for certain hours (overnight, say), easier on the eyes and on your night vision in the dark.
• Auto-restart — if the background player crashes for any reason, it restarts itself automatically instead of just going silent.
• Dynamic color supported and a few background styles (plain, pure black, or a blurred version of the album art).
• Cross-network connectivity — sign in directly (interactive browser login, a device code you enter on another device, or a cached token) and it'll show up in your Spotify Connect list from anywhere, not just when you're on the same Wi-Fi network as it.
• Checks for updates (optional, on by default) — looks for a newer release on GitHub once or twice a day and lets you know, with a one-tap link to go grab it.
• A log screen if something isn't working, so you can see what's going on instead of guessing.
• Hardware button support — media keys on a Bluetooth speaker or headset (play/pause/skip) control playback directly, no need to touch the screen.

Screenshots

OLED-black, portrait	Tinted, idle with log console
Blurred cover art, landscape

What you'll need

• An Android phone or tablet running Android 7.0 or newer.
• A network connection for the Librething device — the same Wi-Fi as the device you're casting from only if you're using Zeroconf discovery; any network works with a direct sign-in instead.
• A speaker or headphones plugged into (or built into) that device.

Building it

You'll need: Android Studio (which also installs the Android SDK/NDK for you), and the Go programming language.

1. Download this project (git clone it, or use Android Studio's "Get from VCS").

2. Build the audio engine. This project plays music using go-librespot, an open-source Spotify Connect implementation, compiled to run directly on Android. Open a terminal in the project folder and run:

   export ANDROID_NDK_HOME=$HOME/Library/Android/sdk/ndk/<your-installed-version>
   ./scripts/build-go-native.sh

   This downloads and compiles everything needed automatically — it just takes a few minutes. (Not sure of your NDK version/path? Open Android Studio → Settings → Languages & Frameworks → Android SDK → SDK Tools tab, and check what's installed under "NDK".)

3. Open the project in Android Studio and press Run, with your Android device connected over USB (with USB debugging turned on).

   Or, to build an installable file instead:

   ./gradlew assembleDebug

   This produces a few files under app/build/outputs/apk/debug/ — install app-arm64-v8a-debug.apk on most modern phones, or app-universal-debug.apk if you're not sure which one fits (bigger file, but works everywhere).

Setting it up the first time

1. Open the app and allow the notification permission when asked (needed to show what's currently playing).
2. Go to Settings and give your device a name — this is what shows up in Spotify's device list.
3. Still in Settings, tap "Disable battery optimization for this app". Without this, Android will eventually pause the app in the background and Spotify Connect will stop working after a while.
4. Back on the main screen, tap the power button to start it. Once it says "Discoverable", it's ready.
5. Open Spotify on any device (on the same Wi-Fi if you are using zeroconf mode), tap the Connect icon (bottom-left, looks like a speaker with a wifi symbol), and your device should appear in the list.

That's it — pick a song and it'll start playing through your device's speaker.

Everyday use

• Play / pause / skip — same controls you'd expect, right on the main screen.
• Volume — drag the volume slider, or use your device's physical volume buttons.
• Gestures (if turned on in Settings) — double-tap to play/pause, swipe left/right to skip, swipe up/down for volume; works on the cover art, or anywhere on screen if the full-screen option is on.
• Fake sleep — tap the moon icon (or it happens automatically) to blank the screen while keeping the music going; tap the screen again to wake it back up.
• Settings are grouped by what they affect — Dashboard look, screen behavior in landscape, playback quality, how it connects to Spotify, and general app behavior like autostart and the crash-recovery toggle mentioned above.
• If something's not working, open the log (the terminal icon) to see what the app is actually doing — it's the fastest way to tell whether it's a Wi-Fi problem, a login problem, or something else. (And it also looks cool)

Where the audio engine comes from

Librething doesn't reimplement Spotify Connect itself — all of that comes from go-librespot by devgianlu, a well-established, open-source Spotify Connect player. This app builds that engine to run natively on Android and wraps it in a proper mobile UI, background service, and settings screen.

This project actually started as go-librespot-termux, a way to run go-librespot on Android through Termux — a workaround, not a real app. After seeing dedicated Spotify Connect gadgets like the Car Thing, it made more sense to build this into an actual Android app instead: same underlying engine, but running natively with its own interface, no Termux needed. The engine is still built from that fork (SEKY443/go-librespot-termux), which carries a handful of Android-specific fixes — most of which have since been contributed back upstream.

A quick licensing note

go-librespot is licensed under GPLv3. This app ships it as a separate program that it launches and talks to — it isn't merged into the app's own code. If you build and share a copy of this app, you're expected to also make the corresponding go-librespot source available (see scripts/build-go-native.sh for the exact version used) and not stop anyone from rebuilding or swapping out that engine themselves. This isn't legal advice — if you're planning to publish this more widely, it's worth having someone qualified confirm that's fine for wherever you're distributing it.