Security

Data minimisation

The most secure file is the one that is never transmitted. Because 123FileConverter converts most formats in your browser, the majority of files handled by the service never travel across the network at all.

Encryption in transit

Server-side conversions are protected with TLS (HTTPS) end to end.

Automatic deletion

Files that are processed on the server, and their converted results, are removed automatically within one hour. Downloads are served through short-lived, cryptographically signed links that cannot be guessed.

Hardening

• Uploads are validated by content (magic bytes), not by file extension.
• Archive extraction is protected against path-traversal (Zip Slip) and zip bombs.
• External tools are invoked without a shell, eliminating command-injection risk.
• Per-IP rate limiting and concurrency caps protect the service from abuse.