A leaked API key can run up a huge bill before you notice. Vallkey keeps your real keys out of your code and gives each app a stand-in key with its own rules: spending caps, AI budgets, allowed endpoints and models. If a key leaks, it can only do what you allowed. See every request, get told when a key shows up somewhere new, and kill any key in one click without touching the real one. Works with 196+ services, including Stripe, OpenAI and Anthropic.