inferpay
Arc Testnet · USDC · x402

AI agents pay USDC
per LLM request.

Send a request. Get a 402. Sign a USDC transfer. Get inference.

Built on Circle Nanopayments and the x402 standard. No accounts, no API keys — the signed payment is the authentication.

Read the docs →Try live demo →

How it works

01
RequestPOST to /v1/chat/completions with an OpenAI-compatible body.
02
402 ResponseServer returns payment instructions: amount, payTo, network.
03
SignClient signs an EIP-3009 transferWithAuthorization off-chain.
04
RetryResend with X-Payment header. Circle validates in milliseconds.
05
InferenceServer proxies to OpenRouter, streams the LLM response back.

Three ways to use InferPay

Pick your starting point — from zero setup to full control.

Recommended

Try Now

Use the live demo below. No wallet, no setup — we pay from our testnet account so you see the full x402 flow.

Zero setup5 req/minArc Testnet
Try Demo ↓

Agent SDK

Run our reference buyer agent. Requires a Circle API key and testnet USDC.

5 min setupUnlimitedArc Testnet
View on GitHub →

Raw API

Build your own x402 client. Full control over wallet and payment signing.

Custom setupUnlimitedTestnet & Mainnet
Read Docs →

Built for the Agent Economy

Your users are scripts and autonomous agents, not people clicking buttons.

Autonomous AI Agents

LangChain, CrewAI, AutoGPT agents get LLM access without human-managed API keys.

MCP Servers

MCP servers that call other LLMs as tools — pay per call, no setup.

Agent-to-Agent Workflows

One agent buys inference from another. USDC is the coordination layer.

Any HTTP Client

Any software that can sign a USDC transfer and send a POST request.

Simple Pricing

Testnet only

Flat rate per request. No subscriptions. No minimums. Testnet USDC.

Meta

meta-llama/llama-3.1-70b-instruct

0.001 USDC

per request

Anthropic

anthropic/claude-sonnet-4-5

0.005 USDC

per request

OpenAI

openai/gpt-4o

0.008 USDC

per request

Anthropic

anthropic/claude-opus-4-5

0.010 USDC

per request

MVP: Fixed price per request, regardless of token count. Production: Token-based pricing with prepaid balances or estimate-and-refund via Nanopayments.

Integration

Three ways to call InferPay from your code.

curl -X POST https://ipayx402.xyz/api/v1/demo/try \
  -H "Content-Type: application/json" \
  -d '{"model":"meta-llama/llama-3.1-70b-instruct",
       "messages":[{"role":"user","content":"What is x402?"}]}'

Live Demo

See the x402 payment flow in action — no wallet required.

Live Demo — Testnet MVP

This demo uses a pre-funded buyer wallet to execute a real USDC payment on Arc Testnet. You don't need a wallet.

Demo buyer:0x9b35...ee0d
Merchant:0x681d...6140
Network:Arc Testnet
Rate limit:5 requests / minute

Instant Settlement

Circle Nanopayments

Off-chain confirmation in milliseconds. No block waiting. Circle batches settlement — merchants get instant credit.

Any LLM Model

OpenRouter

One endpoint. 200+ models: Llama 3.1, Claude, GPT-4o, Mistral, Gemini. Switch models per request.

No API Keys

x402

Payment is authentication. Sign a USDC transfer with EIP-3009, attach it to the request. No accounts, no tokens.

Roadmap

v0.1Live

x402 Proxy

x402 proxy + buyer agent + playground UI

v0.2Next

Nanopayments

Circle Nanopayments integration, gas-free batched settlement

v0.3Planned

Token Pricing

Token-based pricing, usage dashboard, multi-model routing

v0.4Planned

Agent Marketplace

Agent-to-agent marketplace, agents sell skills for USDC

v1.0Future

Mainnet

Mainnet deployment, production security, real economics