What is pay-per-call AI?
Last Updated: April 28, 2026
Pay-per-call AI is a billing model where each API call is priced and settled individually. Per-token for LLMs, per-image for image generation, per-second for video, per-request for data APIs. No subscription, no monthly minimum, no prepaid credits.
How it differs from the alternatives
- vs subscription: no monthly fee. Pay only for what you actually use; spend nothing on idle months.
- vs prepaid credits: no balance to top up, no expiring credits. Each call settles independently.
- vs API key seats: no signup, no billing email, no per-seat licensing. Authorize per-call with a signature.
Why AI agents need it
An autonomous AI agent making 50,000 API calls a day across 12 different providers cannot hold a credit card, fill out 12 signup forms, and manage 12 billing portals. It needs to pay for one call right now, then a different call somewhere else a second later, with no account anywhere.
Pay-per-call AI over a stablecoin (USDC) gives the agent exactly that: per-call authorization with a wallet signature, instant settlement on-chain, no persistent account. The mechanism that makes it work is the x402 protocol.
Pay-per-call AI on BlockRun
BlockRun is a pay-per-call AI gateway. 55+ models, image generation, video, music, and live data APIs — all priced per call, all settled in USDC over x402 on Base, Solana, or XRPL. No API key, no signup, no minimum spend. Free models are available for testing without any payment at all.
Provider cost + 5% margin at settlement — fully transparent on the pricing page.