Syncthing is excellent at one thing: continuously mirroring folders across your machines. But not every transfer is a sync. When you just want to send this file to that device, now, Cynth does it directly and end-to-end encrypted — with native apps and no folder configuration. Here's the honest comparison, including where Syncthing wins.
| Cynth | Syncthing | |
|---|---|---|
| Model | One-time send | Continuous folder sync |
| Setup | Pair and send | Configure shared folders & rules |
| Where files live | On your devices only | On your devices only |
| Native apps | Win · macOS · iOS · Android · Linux | Daemon + web UI; third-party GUIs |
| Send to a contact once | Yes | Not the model |
| iOS | Native app | Limited / third-party |
| Open source | Proprietary, documented protocol | Yes |
| Encryption | End-to-end, mutual TLS per device | End-to-end (TLS) |
You want a folder to stay identical across several machines — a working directory mirrored between your laptop, desktop, and server, updating whenever anything changes. You're comfortable configuring it, and open source is a requirement. For always-on mirroring, that's exactly what it's built for.
You want to send something once — this build, this footage, this folder — to a specific device or person, without setting up an ongoing sync relationship. Native apps on every platform, no folder rules to configure, automatic resume, no size cap, and a send to trusted contacts, not just your own machines.
Cynth is in active development. Join the list and you'll get one email when it's ready for your platform.
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