An open-source Android app for the Kilter Board.

Browse climbs, light up holds, log your sessions — without an account, without Google services, without anyone tracking your training.

85,000+ climbs offline
Custom hold colors
Encrypted local logbook
German & English UI

Get on Zapstore Download APK

Free. No account. Verifiable signed builds. Android 9+.

Browse climbs in CruxCoach — list of climbs filterable by grade, angle, and quality

What CruxCoach does

Built around the things you actually do at the wall — not features the official app needed but you don't.

Browse 85,000+ climbs

Filter by grade, angle, quality, move count, setter. Works offline once the board database is synced.

Light up holds via Bluetooth

Direct BLE to your Kilter Board. Pick custom colors per role: start, hand, foot, top.

Search by hold

Tap holds on the board image. Find every climb that uses that exact combination.

Local, encrypted logbook

Sends, attempts, opinions, sessions — all stored on your device in an SQLCipher database. Never leaves unless you ask.

Share with climbers nearby

Other CruxCoach users at the same board see your current climb over Bluetooth — and you see theirs. No internet, no accounts.

Your training history, portable

Sign in with your Kilter account and CruxCoach pulls your existing logbook over. From there your data stays portable: export to JSON, or turn on automatic encrypted backup that only you can restore.

CruxCoach climb detail screen showing climb name, grade, stats, and the holds marked on a board diagram — Climb detail — grade, stats, and the hold sequence at a glance

CruxCoach logbook view showing logged sends and attempts — Local logbook — every send and attempt stays on your device

Why CruxCoach exists.

On 26 March 2026, Aurora's Kilter app was pulled from the App Store and Play Store after a dispute between Aurora Climbing and Kilter, LLC. Tens of thousands of climbers lost access to their playlists, logbooks, and draft climbs overnight. The new official app shipped half-finished, and people started asking the obvious question: why does my training data live on someone else's server in the first place?

CruxCoach is one answer to that question. Your training history sits encrypted on your phone. Your identity is a Nostr keypair you control, not an account someone can revoke. The board database is content-addressed and downloaded to your device on first sync — once you have it, you have it. And the whole thing is open source under the GPL: anyone can audit it, fork it, run it.

It's narrower than the official app on purpose: Kilter only, Android only. But it's yours.

Privacy by architecture, not by promise

Privacy claims are easy. CruxCoach is built so the privacy holds even if we're lying about it.

No accounts, no signup. Your identity is a Nostr keypair generated on first launch, stored in the Android Keystore.
No Google Play Services. Works on de-Googled phones — GrapheneOS, /e/OS, LineageOS without GApps.
Encrypted local storage. Personal data lives in an SQLCipher database. Encryption key never leaves your device.
No telemetry, no analytics, no ads, no third-party SDKs. Outbound calls go to: Nostr relays you configure, Blossom servers for the board database, Codeberg for update checks, and the Kilter API only when you opt to import your logbook.
No central server we operate. The app uses public Nostr relays and Blossom servers run by independent operators.
Verifiable open-source builds. Code on Codeberg, releases signed, auto-updater pins the developer key on first install.

Install

Two ways to install today. Two more coming.

Zapstore recommended

Privacy-respecting, Nostr-native Android store. Verifies developer signatures. Auto-updates.

Open in Zapstore

Direct APK

Download the signed APK directly from Codeberg releases and install manually. The in-app updater handles future updates.

Latest release

F-Droid soon

Submission planned once the 0.1.3 release lands. Will be the slowest channel to update but the broadest reach in FOSS-Android.

Pending

IzzyOnDroid soon

Third-party F-Droid-compatible repo, faster review, preserves the developer signature. Submission queued.

Pending

For developers

CruxCoach is GPLv3, written in Kotlin Multiplatform with a Jetpack Compose Android frontend. Issues and PRs live on Codeberg.

git clone https://codeberg.org/CruxCoach/CruxCoach.git
cd CruxCoach
bash scripts/setup_dev_env.sh
./gradlew :androidApp:assembleDebug

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