How do you prove your source code existed before a specific date? Git history feels like proof, but it isn't independent. Commit dates come from the developer's own machine and can be set to anything, and history can be rewritten before it's pushed. The strongest approach is to freeze the code at a known point (a tagged release, an archive or a bundle), calculate its SHA-256 fingerprint, and record that fingerprint somewhere nobody in the dispute controls. This guide covers why commit dates are weak on their own, what signed commits and hosted releases add, and a simple routine that gives your code a date that holds up.

Disclosure: I'm Inna Hall, an Australian lawyer and co-founder of TimeBinder, which is mentioned below. This is general information, not legal advice. Copyright, employment and contract law differ between countries, so get advice on your own situation.

When the date of your code matters

Most developers never need to prove when they wrote something.…