Developer tools that never leave your browser
Format JSON, convert timestamps, encode Base64 and more — free, instant, and private by architecture. Every tool on this site runs 100% locally in your browser: there is no server receiving your data, because there is no server at all.
Data formats
Encoding & tokens
Network & time
Why local-only tools?
Most online tools send whatever you paste — JSON payloads from production systems, tokens, internal configuration — to a stranger's server, where it may be logged, cached or leaked. The tools here are different by construction: the page you load contains all the code, and the code runs on your machine. You can verify it yourself: load a tool, disconnect from the network, and it keeps working.
That design has a second benefit: speed. There is no upload, no queue and no round trip, so results appear as fast as your device can compute them — even for multi-megabyte files.
Latest guides
JSON vs YAML: Key Differences and When to Use Each
JSON and YAML carry the same data but behave very differently: syntax, types, comments, failure modes and tooling, plus a practical rule for choosing between them.
GuideWhat Is a JWT? JSON Web Tokens Explained
A JSON Web Token is three Base64URL segments and a signature. How JWTs are structured, how the claims work, how verification really happens, and the mistakes that make them insecure.
GuideBase64 Encoding Explained: Why It Exists and How It Works
Base64 turns binary data into safe text at a 33% size cost. Why the internet needed it, how the 3-bytes-to-4-characters trick works, the variants, and the mistakes to avoid.