Developer Utilities
Base64, JSON, UUIDs, timestamps, regex, and more — all free and running in your browser
Base64/URL encoding, JSON formatting and validation, UUID and random number generation, Unix timestamp conversion, hash generation, a regex tester, and a URL parser/query string builder — all run locally in your browser with no data leaving your machine.
Learn more →Base64 / URL Encoder-Decoder
Encode or decode text as Base64 or a URL component.
JSON Formatter & Validator
Format, validate, and minify JSON with instant error messages.
UUID / Random Number Generator
Generate UUIDs or random numbers within a range.
Unix Timestamp Converter
Convert between Unix timestamps and human-readable dates.
Hash Generator
Generate SHA-1, SHA-256, SHA-384, and SHA-512 hashes.
Regex Tester
Test a regular expression against sample text with live match highlighting.
URL Parser / Query String Builder
Break a URL into its parts, or build a query string from key-value pairs.
JWT Decoder
Decode a JWT's header and payload instantly, right in your browser.
Cron Expression Parser
Get a plain-English description and the next 5 run times for any cron expression.
JSON ↔ YAML Converter
Convert JSON to YAML or YAML to JSON instantly, with validation.
What Is the This Calculator?
Frequently Asked Questions
Are these tools free to use?
Yes, every tool here is completely free, with no sign-up required.
Do these tools send my data anywhere?
No, all processing happens locally in your browser — nothing is uploaded or stored on a server.
Can I use these on my phone?
Yes, all tools are fully responsive and work well on mobile devices.