In spirit, it's somewhat closer to FreeFileSync, but with an integrated networking layer and end-to-end encryption — which means you can synchronize files between computers on the same LAN or across the internet without VPNs or firewall setup. Everything works transparently through the same interface.
The synchronization model is based on DataNodes (which represent repositories, such as servers or NAS devices) and DataSources (the folders or files inside them). A session can include multiple participants, each with one or several DataNodes, and ByteSync handles all comparisons and transfers automatically.
To optimize performance, the engine uses a two-stage inventory process: an initial indexation followed by comparisons limited to items that actually changed. This keeps synchronization fast even with large datasets. There's also a flat mode, useful when structure doesn't matter and you just want to compare or align files by name.
Currently, ByteSync is focused on interactive synchronization — it's not yet automated or daemon-based (CLI integration is planned). But it's already fully functional for discovering and managing differences between repositories, both local and remote.
ByteSync runs on Windows, macOS, and Linux, and the entire codebase is available on GitHub: https://github.com/POW-Software/ByteSync
You can also download binaries and read the documentation here: https://www.bytesyncapp.com
I'd really appreciate feedback and contributors — whether on usability, architecture, or ideas for future features. The goal is to make a solid, privacy-respectful alternative for hybrid file synchronization that remains simple to use and open for everyone.
paulfresquet•2mo ago
ByteSync is meant to give users control and visibility over what’s happening. Instead of syncing in the background, it operates through explicit sessions — you decide when and how synchronization occurs, selecting which changes to apply and in which direction before any transfer happens. This makes it particularly useful for data management, backups, or multi-location setups where you need to understand what’s being moved before it happens.
Each session defines one or several DataNodes (repositories) and DataSources (folders or files). For example, you might have a local workstation with a DataNode containing project folders, a NAS with backups and archives, and a remote server for off-site replication. All of them can be part of the same session, compared and synchronized through end-to-end encrypted exchanges. This model keeps things explicit while still supporting flexible topologies — local or remote, single or multi-participant.
When synchronizing over the internet, transfers go through a temporary encrypted buffer in the cloud, used only as a relay for data exchange. All content is protected with end-to-end encryption (E2EE) — nothing is stored or accessible on the relay, and data exists there only for the duration of the transfer. This allows remote synchronization to work seamlessly without VPNs, firewall rules, or manual network setup.
Under the hood, ByteSync relies on full desktop clients for Windows, Linux, and macOS, along with cloud components that handle orchestration and temporary relaying when needed. A command-line mode is also planned, and the design work for it is already underway.
Performance-wise, ByteSync uses a two-stage inventory process: an initial indexation phase that collects file size and modification timestamps, followed by a comparison phase that computes block-level signatures only for files that show differences. This avoids redundant network round-trips and dramatically improves performance in remote scenarios where latency would otherwise make full scans impractical.