Free tools for developers

UUID generators, JSON formatters, JWT decoders and more — fast, free, and 100% private. Every tool runs locally in your browser; your data never touches a server.

Generators

UUID Generator

Generate RFC 4122 v4, v1 or v7 UUIDs instantly in your browser.

Password Generator

Generate strong, random passwords with custom length and character sets.

Lorem Ipsum Generator

Generate placeholder Lorem Ipsum text — words, sentences or paragraphs.

JSON

JSON Formatter

Format, validate and minify JSON online with instant error detection.

JSON Validator

Validate JSON syntax online with exact line and column error reporting.

JSON Diff

Compare two JSON documents and see exactly what was added, removed or changed.

JSON Minifier

Minify JSON online and see exactly how many bytes you saved.

JSON to CSV

Convert a JSON array of objects into a downloadable CSV file.

CSV to JSON

Convert CSV into a clean JSON array, with type inference and nested keys.

Encoding

Base64 Encode

Encode text to Base64, with optional URL-safe output.

Base64 Decode

Decode Base64 (standard or URL-safe) back to readable text.

URL Encode

Percent-encode text or URLs, with component or full-URI mode.

URL Decode

Decode percent-encoded URLs and query strings back to readable text.

Date & Time

Unix Timestamp Converter

Convert between Unix timestamps and human-readable dates.

Timezone Converter

Convert a date and time across major timezones worldwide.

Security

JWT Decoder

Decode JSON Web Tokens and inspect header, payload and signature.

JWT Generator

Build and sign a JSON Web Token from a custom header, payload and secret.

JWT Inspector

Decode a JWT, verify its HMAC signature, and surface common security issues.

JWT Expiration Checker

Check if a JWT is expired with a live countdown to (or since) its exp claim.

JWT Claims Viewer

See every JWT claim explained in plain English, standard vs. custom.

JWT Signature Verifier

Verify a JWT signature with HMAC, RSA (RS256) or ECDSA (ES256) keys.

Hash Generator

Generate MD5, SHA-1, SHA-256 and SHA-512 hashes from text.

Development

Cron Parser

Parse cron expressions into plain English and preview upcoming run times.

Regex Tester

Test JavaScript regular expressions with live match highlighting.

OpenAPI Viewer

Browse an OpenAPI/Swagger document as a readable, searchable list of endpoints.

OpenAPI Validator

Check an OpenAPI/Swagger document for broken refs, duplicate IDs and other spec violations.

OpenAPI Diff

Compare two OpenAPI/Swagger versions and flag breaking vs. non-breaking changes.

OpenAPI to Postman

Convert an OpenAPI/Swagger document into a downloadable Postman collection.

OpenAPI Mock Generator

Generate realistic mock responses from an OpenAPI/Swagger document, exportable as MSW handlers.