00 · the instrument

A verifiable mark of presence. Nothing more.

01 · Manifesto

The principle is simple. Presence, without exposure.

built into the device機

Hardware-held.

The seal is forged in the Secure Enclave. Keys never leave. The math runs on your iPhone, not on a server we operate.

a practice, not a feed静

No streaks. No nags.

Zetsu does not push. No daily reminder, no "who beat your time" alert. The app waits, quietly, for you to open it.

private circle, no timeline輪

A quiet feed.

Optional private circle for people you trust. Share city, distance and pace. Never your route. No followers. No public timeline.

03 · The artifact

What you actually share. A seal, not a story.

Specimen receipt

The seal speaks for itself.

Anyone can verify: a run of at least N kilometers occurred between two public timestamps, by the holder of this key. The route, the identity and the exact pace stay with you.

Coaches, sponsors, communities. They do not need your map. They need a mark.

claim≥ 5 km · between 04:00 and 05:00 UTC
circuitzetsu/v1
anchor0x4f1c…d22a
sealzk-9b2c…41af
status● verified
04 · The lifecycle

What stays. What leaves.

05 · Boundaries

What Zetsu will never do.

No public map. Your route is never plotted on the internet. No shared layer. No heatmap.
No public timeline. The optional in-app feed is a private circle. No followers, no likes, no leaderboard, no public scroll.
No tracking pixels. Zetsu phones home for nothing. Anonymous build telemetry can be turned off in settings.
No upsell. No drip campaigns. No tiers gating fundamentals. The proof system is the product.
06 · Take your mark

Quiet runners,
step in.

Releasing in summer 2026. Early access to the iOS app, a numbered hanko at launch, and an invitation to the founders' run.

platformiOS 17+ · iPhone 12 and later
launch windowSummer 2026
Mark · 絶

Step into the practice.

One quiet email when we release. Nothing more, nothing else.

Email held as a hash. Unsubscribe by replying once.
07 · FAQ

Honest questions.

No. Strava is a public feed; Zetsu is a private seal. If you want a public log of every run, Zetsu is not for you. If you want a private record with the option to prove it, Zetsu is the instrument.
Each run becomes a zero-knowledge proof. A small cryptographic statement that asserts a property (e.g. "this device covered ≥ 5 km between two public timestamps") without disclosing the underlying data. The proof is a few hundred bytes. The trace stays on your device.
Only the claim you choose to make. There are three disclosure tiers: minimal (a run occurred), standard (distance plus duration window), and city (you ran in this city, opt-in). You decide which seal to share.
Yes, but it is a private circle, not a public timeline. You can share city, distance and pace with people you have invited. Your route, GPS trace and HR samples never leave the device.
Yes. Local export to GPX/FIT is supported. Once it leaves Zetsu it is no longer private. That trade-off is yours to make.
Secure Enclave and tight sensor APIs let us hold keys in hardware and capture motion without backend round-trips. Android is on the map for cohort two, once the proof system is steady.
The verifier and circuit will be open-sourced before public launch. The app is closed-source for now to protect the cohort.