Generator
Generate modern unique identifiers: ULID, NanoID, Snowflake and CUID2. Compare formats, decode ULID timestamps and pick the right ID for your system.
uid-generatorDevelopment
An in-browser GraphQL client: write queries and variables, send them to any GraphQL endpoint, and inspect formatted JSON results or error arrays — perfect for iterating on schemas during development
graphql-playgroundDevelopment
A lightweight in-browser HTTP client (mini Postman): send GET/POST/PUT/DELETE requests with custom headers and body, inspect status, headers, timing, and formatted response — all from your browser
http-request-testerNetwork
Visualize the geographic location, network (ASN/ISP), timezone, and security posture of any IP address as a rich card report
ip-geolocationDevelopment
A searchable, localized cheat sheet for regular expression syntax — character classes, anchors, quantifiers, groups & references, lookarounds, escape sequences, and flags — with a built-in quick tester
regex-cheat-sheetDevelopment
Step through how a regular expression matches a string position by position: visualize match attempts, partial successes, backtracks, and captures — a learning tool for understanding regex behavior, not just the final result
regex-debuggerText Processing
Fetch an RSS or Atom feed by URL (or paste raw XML), parse it, sort items by publish date, deduplicate, apply a time window, and output a clean Markdown summary
rss-feed-markdown-summarizerAstronomy
Compute the sun’s elevation and azimuth (NOAA algorithm) for any latitude, longitude, date and time, plus the length and direction of the shadow cast by an object of a given height, with sunrise/sunset and a full-day shadow curve
sun-position-shadow-simulatorSecurity
Generate RFC 6238 TOTP (time-based, 6/8 digits, 30/60s step) and RFC 4226 HOTP (counter-based) one-time passwords from a base32 shared secret, fully offline with HMAC-SHA1/256/512, plus an otpauth:// URI for importing into Google Authenticator / Authy
totp-hotp-offline-generatorDevelopment
Connect to any WebSocket (ws:// or wss://) endpoint from your browser, send and receive messages, and inspect open/close/error events with codes — ideal for debugging real-time APIs and sockets
websocket-testerDevelopment
Statically check Markdown links for format errors, broken anchors, and undefined references (no network requests)
markdown-link-checkerText Processing
Lint Markdown against ~15 markdownlint rules plus 2 Chinese-typography rules, with line-located reports and one-click auto-fix of safe issues
markdown-lint-style-checker