Damus
Zappr profile picture
Zappr
@nostrich

A Bitcoin platform that lets you talk to Speak to Bitcoin in the language you think in. ⚡

Relays (6)
  • wss://relay.primal.net – read & write
  • wss://relayable.org – read & write
  • wss://holyfit.scuba323.com/relay/ivory – read & write
  • wss://relay.0xchat.com/quartz – read & write
  • wss://relay.nostr.net – read & write
  • wss://relay3.openvine.co/hotel-zulu-ember – read & write

Recent Notes

Zappr  profile picture
What specific thing keeps you on custodial Lightning apps?
Real answers shape what we build next.
#nostr #bitcoin #lightning

2❤️1
BTC Tennis · 3d
Honest answer: inbound liquidity. Custodial apps make receiving just work, while self custody means opening channels, buying inbound capacity, and rebalancing when one side drains. Second is reliability: a large payment can fail mid-route and the user blames the wallet, not the path. Third is restor...
Lightning Faucet · 3d
channel management overhead, mostly. inbound liquidity, backups, watchtowers. phoenix abstracts most of it but still not zero-thought like a bank app.
Nabil · 6d
This perspective really resonates with our journey. True community and human solidarity are what keep hope alive through life's hardest tests. 🎥 I shared my personal story & medical video on my pinned note here: https://primal.net/e/nevent1qqsws6penarh4xws7s2yevvlfaje0dlhwzkw3jatu6azpk43lp0k6ssk...
Lightning Faucet · 1w
does the PRF output stay stable across authenticator firmware updates? that's been the failure mode we've seen with passkey-derived seeds elsewhere.
Zappr  profile picture
Honest answer: the spec doesn't guarantee PRF stability, and we rely on it in the web path.

Best documented case of silent drift: Apple's hybrid/QR PRF bug on iOS 18.0–18.3, fixed in 18.4. No confirmed firmware-level cases, Yubikey isn't field-updatable, Nitrokey/Solo failures are loud (credential just stops working).

The real risk isn't firmware, it's passkey deletion or re-registration. Both silently re-derive to a different, empty wallet. No error thrown.

Fix we're building next: a PRF-independent second unlock path. Until then reveal and write down your 12 words now, while your assertion still works.

Zappr  profile picture
Preparing for Play Store submission. For anyone who has shipped a Bitcoin or Lightning app through Google, what did reviewers flag?
We want to go in prepared.
#nostr #bitcoin #buildingpublic



1
Lightning Faucet · 1w
financial services declaration is the big one, google wants you upfront about custodial vs non-custodial. also expect questions if you mention 'earn' or yield anywhere in copy.
Zappr  profile picture
Boltz went offline in August and took Breez swaps with it, globally.

We migrated our swap layer to Spark.
Lightning is back.

Still non-custodial. Same trust model.
No user funds were ever at risk.

This is what building in public looks like: the blockers, and the fixes.
https://usezappr.xyz

#zappr #nostr #lightning #buildinginpublic

2
Sinal Chain BR · 1w
Com a rede saturada, 1 sat/vB é o mínimo para confirmar swaps. A migração para Spark mantém a não custódia, mas o custo de entrada no Lightning segue crítico.
Lightning Faucet · 1w
good on you for posting the actual failure mode instead of just the fix. curious if spark's swap liquidity has been holding up under load or still early days.
Zappr  profile picture
PRF(passkey,'NOSTR-SALT') → BIP32 → nsec
PRF(passkey,'WALLET-SALT') → BIP39 → Lightning wallet
Client-side. We never see the output.
Same result on any device with the same passkey.
https://github.com/Salmatcre8/zappr

#nostr #bitcoin #webauthn #buildingpublic

1
Lightning Faucet · 1w
does the PRF output stay stable across authenticator firmware updates? that's been the failure mode we've seen with passkey-derived seeds elsewhere.
note13stl0...
Zappr  profile picture
Agreed 💯
The protocol is ready.
The experience is the last barrier and it's the hardest one because it's different for every language and every context. That's exactly where we're focused.