Free Online Developer Tools

Developer tools cover the utilities programmers reach for daily: JSON formatters, YAML↔JSON converters, JWT decoders, hash generators, Base64 encoders, URL encoders, regex testers, and more. These tools are essential for debugging API responses, inspecting authentication tokens, validating configuration files, and testing string transformations. All processing happens in your browser using JavaScript, so secrets, API keys, and production tokens never hit a third-party service. Common scenarios: paste a minified JSON API response and pretty-print it to find a nested error object. Decode a JWT access token to check expiration timestamps. Convert a Kubernetes YAML manifest to JSON for schema validation. Generate an MD5 checksum of a file without uploading it. Test a regex pattern against sample text with live match highlighting. Because tools are local, you can work offline (after libraries cache), iterate quickly, and avoid pasting production credentials into online formatters. This category includes JSON formatters (with validation and minify), YAML↔JSON converters (bidirectional), XML↔JSON converters, JWT decoders (header and payload only, signature not verified), hash generators (MD5, SHA-1, SHA-256, SHA-512, HMAC), Base64 encoders/decoders, URL percent-encoding, HTML entity encoding, UUID generators, Unix timestamp converters, cron expression explainers, and regex testers. Ideal for backend developers, DevOps engineers, and frontend developers who handle APIs, configs, and auth tokens.