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§01 · A different shape

Whistle is built on three open primitives nobody owns. Your phone holds the keys. The relays in between see nothing but noise. There is no Whistle account, no Whistle server, no Whistle database with your trips in it.

Nostr

Identity & message routing. Public-key cryptography, no accounts, no central database.

MLS

RFC 9420 — forward-secure group messaging, the same primitive used in modern secure chat.

Marmot

Protocol glue. Binds Nostr identity to MLS groups in a coherent shape.

This isn't about building a better tracking app. It's about removing tracking as a default assumption.

§02 · Who it's for

The family circle

A small, trusted group — parents, kids, maybe a grandparent. See when someone gets home safely; check if they're still at work or already on their way. Quiet reassurance without the constant ping of a text. Nothing archived, no dossier on your household.

The festival crew

You and six friends arrive at a festival. Phones die, people wander, plans dissolve. Whistle becomes a lightweight coordination layer — no endless "where are you?" chain, no swapping numbers with everyone, no 200MB official app. The group evaporates Monday morning with no lingering graph of who met whom.

The late walk home

Temporary visibility while you're in a taxi or crossing an unfamiliar city. The digital equivalent of "text me when you're back" — a bridge of reassurance during a late-night walk or a solo journey, without handing your data to a platform.

The school trip

A class trip looks organised on paper; in reality it's a constant balancing act — small groups splitting off, missed meeting points, the low-level stress of "where are they now?". Whistle helps coordinate without turning the day into a surveillance exercise. Live for as long as the trip lasts; then gone forever.

Also useful for nights out, pre-wedding gatherings, travel companions, conferences — anywhere you'd otherwise text "where are you?" five times. Make a group, share it, dissolve it when you're done.

§03 · What you get

• End-to-end encrypted location & chatRelays carry only ciphertext — never plaintext, never your group's membership.
• No accountsIdentity is a keypair on your phone, held in the secure enclave. No email, no phone number, no signup.
• Multiple groupsFamily, festival, walk-home circles that don't see each other and don't share a contact list.
• Movement awareBattery-friendly: backs off when stationary, resumes on movement.
• Low-battery alertsYour group gets a heads-up before your phone dies.
• iOS and AndroidSame protocol, fully interoperable. No platform lock-in.
• Pause, leave, or burnStop sharing without leaving the group, leave the group cleanly, or destroy your identity entirely.
• Open sourceAuditable, forkable, no telemetry, no analytics SDKs.

§04 · Just for now

We've quietly drifted into a world where every app wants to know who you are, where you are, and who you're with — all the time. Location sharing, in particular, has shifted from a tool of care into something closer to ambient surveillance: ad-tech incentives, permanent retention, the slow slide of platform enshittification.

There's a fine line between care and control, and most modern apps cross it by default. They turn temporary reassurance into persistent tracking, wrap it in accounts and identifiers, and route it through systems designed to observe, retain, and monetise.

Whistle is built for the moments where you want to be seen, but not watched.

You shouldn't need to sign up, log in, or hand over your data to feel safe. Share your location because it's useful in this moment, with these people — and stop because the moment has passed.

Not forever. Not tied to identity. Not stored somewhere.

Just for now.