Developer Tools
Free online developer tools to format JSON, encode Base64, generate UUIDs and test regular expressions. Fast, private and built for daily coding workflows.
4 free tools
Format, beautify, validate and minify JSON online for free. Spot errors instantly with line numbers. No upload — JSON is processed in your browser.
Open tool →Encode and decode Base64 online for free. Handles UTF-8 text safely. No upload — all conversion runs in your browser for full privacy.
Open tool →Generate UUID v4 online for free. Create one or thousands of unique IDs at once. No upload — UUIDs are generated in your browser.
Open tool →Test regular expressions online for free. See matches highlighted live with capture groups and flags. No upload — runs entirely in your browser.
Open tool →About these tools
These are the small utilities that come up several times a day and never justify installing anything: checking whether a JSON payload is valid, decoding a Base64 string, generating a batch of UUIDs for test data, working out why a regular expression is not matching.
The reason to use a local-only version matters more here than elsewhere. Developer inputs routinely contain things that should not be pasted into a random website — API responses with customer data, tokens, connection strings, log excerpts. Everything on these pages runs in your browser, so nothing you paste is transmitted or logged.
The tools use your browser's own engines: JSON.parse for validation, the native RegExp implementation for pattern matching, and crypto.getRandomValues for UUID generation. That means behaviour matches what your JavaScript code will actually do, rather than approximating it with a server-side library that may differ.
Frequently asked questions
- Is it safe to paste sensitive data into these tools?
- The data never leaves your browser — there is no network request and no logging. That said, treat any browser tab with normal caution, and avoid pasting production secrets anywhere you do not have to.
- Which regex flavour does the tester use?
- Your browser's native JavaScript RegExp engine, so results match exactly what your own JavaScript will do. Patterns written for PCRE, Python or .NET may behave differently.
- Are the generated UUIDs cryptographically random?
- Yes. They come from crypto.randomUUID(), which uses your browser's cryptographically secure random source. Note this requires a secure context, so the tool needs HTTPS or localhost.
- Is there a size limit on input?
- No artificial limit. Very large inputs are bounded by your browser's memory and will simply feel slower to process.