Free developer tools
Small tools for developers that run only in your browser. Decode tokens, make IDs, hash files, test patterns, convert between formats. Nothing you type leaves your machine.
Encode and decode
JWT decoder and inspector
Decode and inspect JSON Web Tokens. Standard claims explained, expiry flagged, header and payload pretty-printed.
Base64 encoder and decoder
Encode and decode Base64, standard and URL-safe, with full UTF-8 support.
URL, HTML, JS and JSON escape and unescape
One page, four targets. Escape and unescape strings for URLs, HTML, JS and JSON.
Generate and inspect
UUID generator (v1, v4, v7) and inspector
v1, v4, v7 and NIL, up to 1000 at a time. The inspector reads back the version, variant and timestamp.
Epoch and Unix timestamp converter
Convert Unix timestamps to and from dates. Seconds or milliseconds found by itself, seven time zones.
Hash generator (MD5, SHA-1, SHA-256, SHA-384, SHA-512)
MD5, SHA-1, SHA-256, SHA-384 and SHA-512 for text or a file. Hex, Base64 or Base64URL output.
JavaScript regex tester
Live JavaScript regex tester. Matches highlighted, every captured group listed, replacement preview.
Cron expression builder and parser
Parse 5-field cron expressions. A plain description and the next 10 fire times in local time and UTC.
Convert
curl to fetch and axios converter
Paste a curl command and get the same request as JavaScript fetch and axios code.
JSON to YAML and YAML to JSON
Convert JSON and YAML both ways. Edit either pane and the other updates live.
JSON to CSV and CSV to JSON
Convert arrays of JSON objects to CSV and back. Choose the delimiter, header row and quotes.
Format and edit
JSON beautify / compress / validate
Pretty-print, minify and validate JSON, with the line and column of each error.
JavaScript beautify / compress
Format and minify JavaScript source.
XML beautify / compress / validate
Pretty-print, minify and validate XML.
G-code translator and toolpath preview
Read CNC and 3D printer G-code as plain English, with a toolpath preview.
LED Matrix Editor
8x8 and 16x16 LED matrix editor with animation frames and code export.
Why browser-only?
Many "free online tool" sites send your input to a server before they show a result. That is fine for a JSON formatter, and not fine for a JWT, a hash, or anything else where the input might hold a secret. Every tool here runs in your browser. Nothing you type or open is uploaded.
Built on what we use ourselves
GoRest is a public REST API with fake data, and a place to try REST. These tools are the ones we reach for when we debug a request, prepare a fixture, or check a token.
Suggest a tool
If you want a tool that is not here, ask in Q&A or write to the address on the about page.