Cynth
Changelog

What changed, in plain terms.

Cynth is in active development ahead of early access. This page tracks what was built, what was fixed, and what's next — no version-number theater, no adjectives.

July 2026Product

Text send, previews, and fewer prompts

  • Send text and clipboard contents between devices — a snippet, a link, a one-time code. The text travels only over the encrypted peer channel, the same QUIC path as file bytes; the servers see that something was offered, never what it says. Received text arrives with a Copy button.
  • Image previews in the accept prompt. Sending a single image now shows the receiver a small thumbnail before they accept. The preview is encrypted to the receiving device's key before it leaves the sender, so the signaling server forwards it without being able to render it.
  • Auto-accept from your own devices. Transfers between devices on the same account skip the accept prompt by default — it's your data moving between your machines. A toggle in every client turns it off.
  • All three shipped in all five clients — Windows, macOS, iOS, Android, Linux.
July 2026Product

Friends: send to people, not just your own devices

  • Add a friend by email, username, or user ID. Friendship is mutual by design — both sides must add each other before any device becomes visible. One-sided adds see nothing.
  • Usernames — claim one so people can add you without sharing your email address.
  • Sending to a friend's device uses the exact same path as your own devices: direct where possible, blind relay as last resort, mutual TLS on per-device keys throughout. The servers broker visibility; they still never see file contents or names.
  • Remove a device from your account on any platform. The removed device is signed out and can no longer send to or receive from the account; files already transferred stay where they are.
  • Both features shipped in all five clients — Windows, macOS, iOS, Android, Linux.
July 2026Site

Security page, changelog, and privacy-respecting analytics

  • /security is live — the full security model and threat model: per-device Ed25519 identity, mutual TLS over QUIC, what our servers can and cannot see, and what Cynth does not protect you from.
  • This changelog page.
  • Early-access waitlist hardened: bot verification on signup, one welcome email per address, ever.
  • Site analytics moved server-side — no client script, no cookies, no IP or user-agent stored.
July 2026Product

Xlip becomes Cynth

  • The project's working name, Xlip, is retired. Everything now ships as Cynth — the apps, the protocol endpoints, the infrastructure.
  • Production endpoints moved to c.cynth.app (API and signaling) and d.cynth.app (relay). All five clients rebuilt against the new endpoints.
  • cynth.app launched with the early-access waitlist.
July 2026Clients

Five platform clients on one core

  • Native clients for Windows, macOS, iOS, Android, and Linux, all built on the same Rust transfer core through a shared C ABI — the same direct transfer between any two of your devices.
  • iOS Share Extension: send from any app's share sheet.
  • End-to-end acceptance suite runs real transfers against the production stack, including a forced-relay path to prove the fallback stays blind.
July 2026Core

The transfer engine

  • QUIC with mutual TLS on per-device Ed25519 keys — both ends prove their identity before a byte moves.
  • Resumable transfers — a dropped 400 GB send picks up where it stopped, not from zero.
  • Direct-first connection paths — LAN discovery via mDNS, then WAN hole-punching, then an encrypted DERP-style relay as last resort. The relay forwards ciphertext; it cannot decrypt what it carries.
  • Production servers deployed: API, signaling, and relay, with nightly backups of account metadata (never file data — there is none stored).
Early access

One email when it's ready. Nothing else.

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