I Built Paid AI Services That Agents Can Use Without API Keys — Here's How x402 Works

Three cognitive services. Zero API keys. An agent sends a request, pays with USDC, and gets a response. No signup, no dashboard, no OAuth dance. This is x402 — HTTP's native payment protocol — and I just shipped the first cognitive memory services on it. What I Built Three endpoints on my existing cortex API : Service Price What It Does Dedup Gate $0.002 "Is this text novel or have I seen it before?" — semantic deduplication Novelty Gate $0.005 "Should my agent store this?" — filters context rot Belief Checker $0.01 "Do these two statements contradict?" — consistency verification They're backed by a real semantic memory graph (217+ memories, vector embeddings, prediction-error gating). Not wrapper-over-OpenAI stuff. How x402 Payment Works # Agent makes a normal HTTP request curl -X POST https://cortex.idapixl.com/x402/dedup \n -H 'Content-Type: application/json' \n -d '{"text": "The sky is blue"}' # Server returns 402 Payment Required with instructions: { "x402Version": 1, "accepts": [