Online Dev Tools is a browser-based toolkit for developers and security engineers. All tools run locally in your browser so you can inspect, transform, and debug data without uploading files or sending sensitive information to external servers. Includes utilities for JSON formatting, JWT decoding, regex testing, base64 encoding/decoding, hashing, URL parsing, CSP analysis, YAML validation, and more. Open a tool, paste your data, get useful output, and continue building.