code and cipher tools
Codes & Ciphers tools
Offline code and cipher tools decode the historical character codes and classical ciphers that turn up in CTF challenges, puzzle hunts and old archives — Hollerith punch cards and the other codes machines and people once used to carry text — entirely in your browser, with every table checked against a published source.
Every Codes & Ciphers tool
About code and cipher tools
A CTF challenge that hands you a photo of a punch card is testing whether you can work out which code made it, not whether you can count holes. These tools are built around that: they read input under every variant at once and rank the results, instead of making you guess the keypunch or the alphabet first. The tables come from primary references — keypunch manuals, published standards, the emulators that run the original software — and each is checked against a second, independent source by an automated test suite, because a decoder with one wrong cell gives you a plausible wrong answer. Everything runs locally, so an unsolved flag never leaves your machine.
Why pick offline code and cipher tools
- Zero uploads — data never leaves your browser
- No cookies, ads, fingerprinting, or cross-site tracking
- Free, no signup or account required
- Works offline once loaded; installable as a PWA
- Verifiable in DevTools — zero network calls when you press a button