Free Online Developer Tools

A fast, private toolkit for everyday development tasks — test APIs, format and validate JSON, decode tokens, generate hashes and IDs, and more. Everything runs in your browser. No sign-up, nothing uploaded.

⚡ 16 tools · 100% client-side · no tracking
</> API Tester
Send REST requests with headers, auth, bodies, cURL import & history.
{ } JSON Formatter
Validate, beautify, minify & explore JSON in a collapsible tree.
⇄ JSON Convert
JSON → YAML, CSV, TypeScript interface or query string.
± JSON Diff
Compare two JSON documents and see what changed by path.
JWT JWT Decoder
Decode a token's header, payload & claims and check expiry.
64 Base64
Encode & decode Base64 with UTF-8 and URL-safe support.
% URL Encode
Percent-encode/decode and parse a URL's query string.
# Hash
MD5, SHA-1, SHA-256, SHA-384 & SHA-512 of any text.
ID UUID
Generate UUID v4 and ULID identifiers in bulk.
•• Password
Strong random passwords with custom character sets.
Mock Data
Lorem ipsum text and realistic mock JSON records.
⏱ Timestamp
Convert Unix epoch ↔ date with local, UTC & ISO output.
◐ Color
Convert HEX/RGB/HSL and check WCAG contrast.
Aa Case
camelCase, snake_case, kebab-case, slugify & more.
.* Regex
Test regular expressions with live match highlighting.
⇥ cURL → Code
Convert a curl command to fetch, Python or Node.js.

A private, browser-only developer toolkit

These free online tools are designed for developers who want quick, no-fuss utilities without installing software or signing up. Every tool — from the API tester and JSON formatter to the JWT decoder, hash generator and regex tester — runs entirely client-side in your browser. Nothing you paste is ever sent to a server, so it is safe to use with tokens, payloads and private data.

Frequently asked questions

Are these tools free? Yes — all 16 tools are free with no account or limits.

Is my data private? Yes — everything is processed locally in your browser.

Do they work offline? Once loaded, most tools work without a connection because they are static pages with no backend.