gchq.github.io/CyberChef (via) CyberChef is “the Cyber Swiss Army Knife—a web app for encryption, encoding, compression and data analysis”—entirely client-side JavaScript with dozens of useful tools for working with different formats and encodings.
It’s maintained and released by GCHQ—the UK government’s signals intelligence security agency.
I didn’t know GCHQ had a presence on GitHub, and I find the URL to this tool absolutely delightful. They first released it back in 2016 and it has over 3,700 commits.
The top maintainers also have suitably anonymous usernames—great work, n1474335, j433866, d98762625 and n1073645.
Recent articles
- The Summer of Johann: prompt injections as far as the eye can see - 15th August 2025
- Open weight LLMs exhibit inconsistent performance across providers - 15th August 2025
- LLM 0.27, the annotated release notes: GPT-5 and improved tool calling - 11th August 2025