Your AirPods, at home on a Googlebook.
Battery for each bud and the case, noise control, conversation awareness, stem presses that show
the desktop or open an app, and head gestures: nod for yes, shake for no.
⬇ Download HearOnLink.apk · Install · Features · Privacy · What's new
A personal hobby project by Fika Labs, proudly developed on a Googlebook. Not affiliated with or endorsed by any employer, or by Apple (more).
AirPods work on any Android device as Bluetooth headphones, but everything that makes them nice lives in Apple's settings. HearOn Link talks to your AirPods the way an iPhone or Mac does, over their own control channel, and brings those settings to your Googlebook and your Android phone. No root, no account, no internet.
- Battery for each part. Left, right and case, with charging, in the app, the Quick Settings tile, a quiet notification and a home-screen widget. When a part stops reporting (a bud back in a closed case, the case on its own), HearOn Link shows its last level with how long ago it was seen, and the case's own Bluetooth adverts fill in 1 % levels whenever you open it nearby.
- Listening modes. Off, Transparency, Adaptive and Noise Cancellation in one tap, plus which modes a press-and-hold switches between, Adaptive's "less or more noise" slider and Noise Cancellation with one AirPod.
- Conversation awareness and personalized volume. Turn them on or off; while you talk, HearOn Link lowers what's playing, then brings it back.
- Ear detection. Pause when you take an AirPod out, play again when it goes back in (only if HearOn Link paused it), pause when you fall asleep.
- Stem presses, your way. Press once, twice, three times or hold, for both buds or each on its own: play or pause, next, previous, volume, mute, switch noise control or go straight to one listening mode, conversation awareness on or off, voice assistant, Show desktop, or Open an app you pick. Presses you leave on "AirPods default" stay with the AirPods, so they work the same with your other devices.
- Head gestures. Try them in a live demo that says Yes or No, calibrate them to your own head, and turn on "anytime" to map a nod and a shake to actions (shake to show the desktop, for example). On phones, nod to accept a call and shake your head to decline.
- Everything else the AirPods report. Press speed and hold duration, volume swipe, call controls, which bud's microphone to use, tone volume, case sounds, custom EQ, optimized charging, renaming, and model, firmware and serial numbers. Heart rate and hearing protection on AirPods Pro 3.
The head-gesture demo: nod and the shape turns into a Yes, shake and it's a four-leaf No.
- A proper desktop window. It resizes freely, down to a phone-sized column, and re-lays itself out as you drag instead of restarting; plugging in a keyboard or mouse doesn't restart it either.
- One calm window. Your AirPods sit on the left (battery, listening mode, the main switches) and settings on the right. The window's own title bar is painted to match the header just below it; nothing floats over the content.
- Quick Settings. The tile shows the listening mode and battery. A tap opens a small panel with the essentials; a long-press opens HearOn Link.
- Starts on its own. You pick your AirPods once and confirm them in Android's own dialog. From then on HearOn Link wakes up when they connect, without a battery-optimisation exception.
- Stem presses and head gestures for the desktop. Show the desktop or open any app from a press or a shake of the head, without an accessibility service: Android allows it for the AirPods you confirmed in its own dialog.
- A notification with three numbers. Left, right and case as Android 17 metrics, with one-tap listening modes.
The Quick Settings panel, and stem presses with a press twice to open the calculator.
On phones it's the same app in one column, with pages for each group of settings.
HearOn Link shows only what your AirPods report they support.
| AirPods 2 | AirPods 3 | AirPods 4 | AirPods 4 ANC | Pro | Pro 2 | Pro 3 | Max | |
|---|---|---|---|---|---|---|---|---|
| Battery, rename, details | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Ear detection | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | |
| Stem presses | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | |
| Listening modes | ✓ | ✓ (no Adaptive) | ✓ | ✓ | ✓ (no Adaptive) | |||
| Conversation awareness, Adaptive | ✓ | ✓ | ✓ | |||||
| Personalized volume | ✓ | ✓ | ✓ | ✓ | ||||
| Head gestures | ✓ | ✓ | ✓ | ✓ | ✓ | |||
| Heart rate, hearing protection | ✓ |
Beats with an Apple chip get whatever they report too. The feature table comes from public protocol research; the app follows what your own AirPods say.
What it can't do. Some things need an Apple device or root access, and HearOn Link leaves them out: Find My, spatial audio with head tracking, Siri, audio sharing, firmware updates, hearing aid and hearing test, transparency tuning, loud sound reduction, and automatic switching between your devices. Android's own Bluetooth settings still show one battery number, because only system apps can change that. Overview, Back, screenshots and locking the screen from a press would need an accessibility service, and HearOn Link doesn't have one.
HearOn Link is made for Googlebooks (Googlebook OS, Android 17). On phones it needs Android 17, or Android 16 QPR3 on a Pixel: older Bluetooth stacks can't open the AirPods' control channel without root.
- On your Googlebook or phone, download HearOnLink.apk from the latest release.
- Open it from Chrome's downloads or the Files app. If Android asks, allow Chrome (or Files) to install apps, then tap Install.
- Open HearOn Link and follow the short setup: allow Nearby devices, pick your AirPods in the list and confirm them in Android's dialog, add the Quick Settings tile, allow notifications.
To update, install a newer HearOnLink.apk over the old one; your settings stay.
Show desktop and Open an app work once you've confirmed your AirPods in Android's dialog (the setup's second step; if you skipped it, the app asks when you first pick one of these actions). HearOn Link has no accessibility service and needs no special settings.
Only one app at a time can talk to your AirPods this way: close CAPod or LibrePods if you use them.
HearOn Link has no internet permission, so it can't send anything anywhere. There are no accounts, ads or analytics. Your AirPods' state, your settings and your head-gesture calibration stay in the app's private storage on your device. Head motion is read only while the demo or calibration is open, a call rings (if you turned on answering with your head) or "Use head gestures anytime" is on with an AirPod in your ear. The privacy policy has the details, permission by permission.
AirPods speak Apple's accessory protocol over a classic Bluetooth L2CAP channel. Until recently
Android's Bluetooth stack dropped that channel, which is why AirPods apps needed root. Android 17
(and Pixel's Android 16 QPR3) fixed it, so a normal app can now open the channel, with one catch:
Android has no public call for a classic L2CAP socket, so HearOn Link reaches the hidden
BluetoothDevice.createL2capSocket through AndroidHiddenApiBypass.
Everything else uses ordinary Android APIs: the companion-device manager, a connected-device
foreground service, a Quick Settings tile, notifications and Glance widgets. There is no
accessibility service: showing the desktop or opening an app from a press is an ordinary activity
start, which Android allows from the background for the companion app of a device you picked.
The protocol code, the head-gesture detector and the Bluetooth advert decoder are plain Kotlin
with no Android in them (core/), tested with JUnit, partly against packets captured from real
AirPods Pro 2. Head gestures use our own detector: each axis is scaled by a per-user calibration
(still, nod, shake), and a gesture counts after two swings on one axis that clearly outweigh the other.
Everything here was researched, written, built and tested on a Googlebook, in its built-in Linux Terminal:
- A tiny probe app, built without Gradle in the Terminal and run over adb, proved on day one that the AirPods' control channel opens without root on Android 17.
- The Kotlin core is tested in the Terminal in seconds; the app is Kotlin and Jetpack Compose with Material 3 Expressive, built with Gradle in the same Terminal and installed on the Googlebook's own Android over adb.
- The screenshots are the app's real UI, drawn by the app itself on a private virtual display with sample AirPods, so nothing on the actual screen was captured.
With a little help from Claude.
Needs JDK 21 and the Android SDK (platform 37).
./gradlew :core:test # protocol, battery cache, gestures, calibration, BLE adverts
./gradlew :app:assembleDebug # app/build/outputs/apk/debug/app-debug.apk
./gradlew :app:assembleRelease # signed if ~/.config/hearonlink/keystore.jks and keystore.pass existBuilds you make yourself are signed with your own key, so uninstall a release before installing
one. ./hol is the development helper (build, install, test hooks, off-screen renders) for a
Googlebook connected over Wireless debugging. CLAUDE.md explains how the code is
organised, and docs/RELEASING.md how releases are made (a tag, built and
signed on GitHub).
HearOn Link is my personal hobby project, published as Fika Labs. It has no affiliation with my employer: my employer didn't make, sponsor, review or endorse it, and HearOn Link doesn't endorse my employer or its products either. The views, choices and any mistakes here are mine alone.
It's also an independent app: it isn't made by, affiliated with, sponsored or endorsed by Apple Inc. AirPods, AirPods Pro, AirPods Max and Beats are trademarks of Apple Inc., registered in the U.S. and other countries and regions.
HearOn Link stands on the shoulders of the LibrePods project and the people whose AirPods research it builds on. HearOn Link doesn't include their code: its protocol code was written independently from the documented byte layouts and our own packet captures.
— Fika Labs
HearOn Link is free software under the MIT License. It includes the following, listed with their licences in THIRD_PARTY_NOTICES.md and in the app (Settings › About HearOn Link › Open-source licences), which also shows the full licence texts:
- HearOn Sans: Google Sans Flex, subset and renamed as the SIL Open Font License 1.1 allows.
- AndroidHiddenApiBypass (Apache License 2.0).
It uses Jetpack Compose, AndroidX (including Glance and Graphics Shapes), Kotlin, kotlinx.coroutines and kotlinx.serialization (Apache License 2.0, full text).