Macaroon Tokens vs API Keys: Why Capability-Based Auth Beats Identity-Based Auth for AI Agents

API keys tie identity to unlimited access. Macaroon tokens embed capabilities and constraints. For AI agents that need delegation and budget limits, the difference is everything. Read the full article on SatGate.io: https://satgate.io/blog/macaroon-tokens-vs-api-keys The Problem with API Keys for AI Agents Every API authentication system makes a fundamental choice: identify who the caller is, or specify what the caller can do. For twenty years, web APIs have chosen identity. Get an API key, prove you're legitimate, access everything your account allows. AI agents break that model. An agent doesn't just call your API — it delegates to sub-agents, spawns parallel tasks, and operates under budgets set by entities three delegation layers up the chain. Why Macaroons Solve the Delegation Problem Macaroons flip the authentication model. Instead of asking "who are you?" they embed the answer to "what can you do?" directly into the token. A macaroon is a capability token — it carries specific p