Some browser-based tools I built for myself that you may find helpful.
A basic SAML decoding tool. Handles url & base64 decoding, deflate compression, and XML formatting.
A Branca token creation and decryption tool, written in .NET using ScottBrady.IdentityModel. Useful when testing your own implementation.
An online JWT generator for creating test and sample data. Runs completely within the browser and includes key generation and free-form header and payload claims.