Dev Toolkit — by freetoolspot

Developer text utilities: format JSON, decode JWT, encode Base64/URL, test regex — fully offline in your browser.

A focused set of text utilities for developers, all running entirely in your browser. Includes: • JSON Formatter — prettify, minify, and validate JSON. Pick 2-space, 4-space, or tab indentation. Live error messages. • Base64 Encode / Decode — UTF-8 safe, two-way text ↔ Base64. • URL Encode / Decode — percent-encode strings for query parameters and URL components. • JWT Decoder — decode the header and payload of a JSON Web Token. Signature is shown but not verified (verification requires the secret key). • Regex Tester — live JavaScript regex matching with highlighted matches and configurable flags. Privacy: 100% client-side. No data is collected, transmitted, or logged. The extension requests zero permissions and works fully offline. Part of the freetoolspot.com toolkit — visit the site for 30+ more browser-based utilities (CSV viewer, color tools, hash, password generator, and more).