Everyday utilities for coding, debugging, and testing.
This page brings together our free online developer tools — a hand-built collection of utilities for everyday coding, debugging, and API work. Format and validate JSON, encode and decode Base64 or URL components, test regular expressions with live match highlighting, decode JWT tokens at the claim level, convert colors between HEX, RGB and HSL, render Markdown to HTML, diff two pieces of text, build cron expressions, and inspect SVG, GeoJSON or raw binary data — all directly in your browser, with no registration and nothing sent to a server.
Whether you're debugging an API response, decoding a session token to check its expiry, comparing two configuration files, generating a cron schedule for a backup job, or pasting a hex dump from a serial capture, the 14 tools below cover the recurring tasks that backend, frontend, and embedded developers run dozens of times a day.
g, i, m, s,u) and capture groups. The tester highlights every match and shows group indices so you can confirm a pattern before shipping it.header.payload.signature tokens used for stateless auth. The decoder reveals header algorithm, payload claims (iss, sub, exp, etc.) and tells you whether the token is expired — useful when an API returns 401.crontab, Kubernetes CronJobs, and most CI/CD platforms. Build one visually and read it back in plain English to confirm your weekly backup actually runs on Sunday at 03:00.