AlterSend

AlterSend moves files straight from one device to another, encrypted end-to-end, without touching cloud storage. Nothing is written to a server in between. No account required, no file size cap for direct transfers, and it works across Mac, Windows, Linux, iOS, and Android.

It fills a gap that tools like LocalSend and PairDrop leave open: those only work on the same local network. AlterSend works just as well across the internet, same room or different continents. WeTransfer uploads and stores your files, capped at 2 GB on the free tier. AirDrop is Apple-only. AlterSend is cross-platform, storage-free, and unlimited for direct connections.

How it works:

• Pairing uses a QR code or short code once. After that, your devices recognize each other automatically.
• Fresh session keys are generated for every transfer and held only in your OS keychain. The secret never leaves your devices.
• No-install sharing lets recipients download via a browser link, straight from your device, with nothing to sign up for.
• Resumable transfers pick up where they left off after a dropped connection or closed laptop.
• Relay fallback kicks in when a direct connection isn't possible. The relay is still end-to-end encrypted, so it can't read your files. Relay-routed transfers are capped at 20 GB (app-to-app) or 10 GB (browser links); direct transfers stay unlimited.
• Folder support means a single text note and a 200 GB project folder move the same way.

The client is Apache-2.0 licensed. You can audit the code rather than take privacy claims on faith. If you want to remove the relay size cap entirely, you can self-host the relay component.

For anyone regularly moving large files between their own devices, or sending to someone who won't install anything, it's a practical alternative to cloud-based services like Tresorit or Resilio Sync that require accounts or ongoing storage costs.