Format, inspect, convert and debug without leaving your browser. Utilities for data, encoding, security, time, networking and everyday development, plus references written from the standards.
Try json · jwt · cron · uuid · chmod · 404 — or press / anywhere.
Paste JSON on the left. Processing stays local.Format, validate, inspect and convert structured data.
Encode and decode text for transport and URLs.
Inspect tokens and compute hashes, locally.
Identifiers and random values from a secure source.
Test and debug everyday development inputs.
Timestamps, epochs and date representations.
Addressing and subnet math.
Scheduling and Unix system utilities.
Every tool in the catalog runs as JavaScript in your browser. Formatting, decoding, hashing and calculating happen locally; nothing you paste is uploaded or logged. Each tool page carries the LOCAL mark only when that is true, and the privacy page describes what the web server does see.
Errors say where and why: line, column and the likely cause. References cite the RFC they are based on and show when they were last checked.