Magic Number Browser is part of DevStudio — a free, in-browser collection of developer utilities that work without sign-up, installation, or any backend service. Searchable file-signature database — extension, MIME, hex prefix, byte offset and description for archives, documents, images, audio, video, executables, scripts, databases, disk images, fonts and crypto containers, all running entirely on your device. Because the page never uploads what you paste, you can run sensitive payloads, configuration files, secrets, or production data through it with confidence: nothing leaves your browser tab. Use Magic Number Browser for ad-hoc debugging, code review, log triage, release prep, learning a new format, or as a quick scratchpad while you build. If you use this tool a lot, pair it with IP / CIDR, IPv6 Shortener, MAC Tools, and the rest of the DevStudio toolkit for related developer workflows.