Online Developer Tools

Free browser-based utilities for JSON formatting, UUID generation, encoding, and more. Everything runs locally - no install, no signup, nothing leaves your device.

About Developer Tools

ToolMatic's developer tools give you instant access to the utilities you reach for daily - JSON formatting, UUID generation, encoding, and more - without installing anything or leaving your browser.

Whether you're debugging an API response, generating test data, or decoding a Base64 payload, these tools are built to be fast, accurate, and zero-friction. Open a tool, paste your input, get your result.

Every tool in this category processes data entirely within your browser using JavaScript. Nothing is uploaded, stored, or logged.

How to choose the right tool

If you are working with API payloads, start with the JSON Formatter to pretty-print responses, the JSON Validator to verify syntax, or the JSON Lint tool to catch duplicate keys and trailing commas.

For encoding and decoding, the Base64 Encoder / Decoder and URL Encoder / Decoder handle the two most common encoding schemes in web development. Use them to debug query strings, decode headers, or prepare data for transport.

Need a unique identifier? The UUID Generator produces spec-compliant v4 UUIDs. To trim payload size before shipping, the JSON Minifier strips whitespace from valid JSON.

Frequently asked questions

Are these online developer tools free to use?
Yes - every developer tool on ToolMatic is completely free. There is no account, no signup, and no usage limit. Open any tool and start using it immediately.
Do these tools work offline?
Currently, an internet connection is required for the first load. Once the page is loaded, most tools continue to work because they execute entirely in your browser using JavaScript. Offline-first support via service-worker caching is planned for a future release.
Do you store the JSON or data I paste in?
No. All ToolMatic developer tools execute client-side using JavaScript in your browser. Your inputs are never transmitted to ToolMatic servers. No account or signup is required. You can verify this yourself by opening your browser's DevTools Network tab - you will see zero outbound requests carrying your data.
What is the difference between a JSON formatter and a JSON validator?
A JSON formatter takes valid JSON and re-indents it for readability - it assumes the input is already valid. A JSON validator checks whether the input conforms to the JSON specification and reports syntax errors. Use the JSON Formatter when you need readable output, and the JSON Validator when you need a strict spec check.
Is it safe to decode a JSON Web Token (JWT) online?
For inspection of decoded claims, browser-based JWT tools that run entirely client-side never send the token to a server. However, never paste a production token that you intend to reuse: any token that touches your clipboard or a third-party tool should be considered exposed. For production debugging, use short-lived tokens or revoke the token after inspection.