Keep: FROST Nostr Signer

Keep: FROST Nostr Signer

FROST threshold signer and Nostr event signer for Android

PrivKey LLC Security

Download (30 MB) Website

Screenshots

Screenshot of Keep: FROST Nostr Signer Screenshot of Keep: FROST Nostr Signer Screenshot of Keep: FROST Nostr Signer Screenshot of Keep: FROST Nostr Signer Screenshot of Keep: FROST Nostr Signer Screenshot of Keep: FROST Nostr Signer

Description

Keep is a FROST (Flexible Round-Optimized Schnorr Threshold Signatures) threshold signing app and dedicated Nostr event signer for Android. It lets you hold FROST key shares on your phone and sign Nostr events without any single device ever holding the full private key.

Keep implements the NIP-55 Android Signer protocol and NIP-46 remote signing, so any compatible Nostr client can request signatures directly.

Features:
- FROST threshold signing (2-of-3, 3-of-5, etc.)
- NIP-55 Android Signer protocol
- NIP-46 remote signing (bunker service)
- Import and export FROST shares via QR code or text
- Multiple account support
- Per-app signing permissions and policies
- Biometric and PIN authentication
- Hardware-backed key storage (Android Keystore)
- NIP-44 encryption and decryption
- SOCKS proxy support (Tor)
- Encrypted backup and restore

What’s new (1.3.2)

Security update. A certificate authority whose keys were compromised is no longer trusted for relay connections. Switching or removing an account now disconnects the bunker apps paired under it, and its remembered approvals no longer carry over. Revoking a bunker app cuts it off at once, even while the bunker is off. Stored settings that cannot be read now keep their restrictions instead of resetting. Bunker apps will ask once more for actions you had set to remember.

Versions

Version Date Size Requires Android Download
1.3.2 current
c4f54b276bc267ce…
 2026-10-25 30 MB API 33
1.3.2
ece8d5db273aff2e…
 2026-10-25 28 MB API 33
1.3.1
7020486b346a30b2…
 2026-10-12 28 MB API 33
1.3.1
be5017b2671df66d…
 2026-10-12 26 MB API 33
1.2.0
d36c6e87a89d2757…
 2026-08-03 27 MB API 33
1.2.0
57ca188ae12ea5b7…
 2026-08-03 25 MB API 33

Permissions

What the app asks the system for. Android only grants sensitive access after you confirm it.

  • Internet accessSend and receive data over the internet.
  • BiometricsUnlock with fingerprint or face.
  • CameraTake photos and videos.
  • Run at startupStart automatically after the device is switched on.
  • Network stateCheck whether and how the device is connected.
  • Foreground serviceKeep running in the background, visible in the status bar.
  • FOREGROUND_SERVICE_SPECIAL_USE
  • NotificationsShow notifications.
Show 3 more permissions
  • USE_FULL_SCREEN_INTENT
  • FingerprintUnlock with a fingerprint.
  • keep.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION

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