Agent Vault is an open-source credential management system designed specifically for AI agents. It acts as an intermediary between AI agents and the APIs they need to call, storing credentials server-side and brokering access without exposing secrets to the agent. When an agent makes an HTTP request, Agent Vault intercepts it, injects the appropriate credentials (such as API keys for LLM providers), and forwards the request to the target service. This architecture prevents credential exfiltration attacks where a compromised or manipulated agent could leak sensitive secrets.