Some browser-based tools I built for myself that you may find helpful.
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.
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.