Whenever you work with Json Web Tokens (JWT’s) generating them for testing is always a hassle as they usually are required to expire quite quickly (like in the order of minutes). To make that easier I wrote a small utility in node.js to generate JWT’s compatible with the Salesforce OAuth 2.0 JWT Bearer Flow.
Code is on Github at https://github.com/lekkimworld/salesforce-jwt-generator
YMMV!
lekkimworld.com 