Automated, cross-chain stablecoin payments for APIs, agents, and smart contracts — powered by x402, Chainlink CCIP, and EIP-3009.
🥇 Winner of the Cross-Chain Solutions track for the 2025 Chainlink Chromium hackathon.
HTTPayer is the missing link for monetizing APIs and digital services with crypto. It's a server framework and SDK suite that brings the long-awaited "HTTP 402 Payment Required" standard to life for the Web3 era, letting any API, app, or smart contract require and automate stablecoin payments (USDC) across chains.
Built on x402, Chainlink CCIP, and EIP-3009, HTTPayer makes crypto payments as simple as traditional API keys:
- No wallet UX required: Account abstraction and automated payment flows mean users and agents can pay for APIs without manual wallet steps.
- Multi-chain by default: Accept payments from multiple EVM chains (Base Sepolia, Avalanche Fuji, and more), with liquidity managed by a treasury service using Chainlink CCIP.
- For devs, agents, and contracts: Simple Python/TypeScript SDKs enable instant paywalling, while Chainlink Functions let smart contracts consume paid APIs and receive valuable data (weather, credit scores, etc.).
HTTPayer transforms stablecoin payments into a drop-in middleware layer—just like Stripe, but composable, cross-chain, and designed for the future of Web3:
- Monetize APIs in minutes: Drop-in Python/TypeScript SDKs for instant paywalling, no deep crypto infrastructure needed.
- Automate everything: Handles 402 responses, payment signing, and retries automatically—enabling seamless access for users, agents, and smart contracts.
- Cross-chain liquidity: Treasury service manages USDC across EVM chains using Chainlink CCIP, unlocking new DeFi primitives and composable finance.
- Smart contract integration: Chainlink Functions let contracts trigger off-chain paid API calls, bridging on-chain logic with real-world data.
- Built for the future: Designed for DeFi, tokenization, AI agents, and agentic automation.
Real impact:
- For Developers: Instant API monetization without complex crypto infrastructure
- For Users & AI Agents: Seamless, automated access to paid APIs and services
- For Smart Contracts: Secure, on-chain interaction with monetized off-chain APIs
- For the Web3 Ecosystem: A real, interoperable way to do Stripe-style payments with crypto—composable, cross-chain, and future-proof
🔗 API Monetization
Instantly add stablecoin paywalls to any API—weather data, financial feeds, AI
models, or premium content.
🤖 AI Agent Payments
Let autonomous bots and AI agents pay for data and services on demand, enabling
truly autonomous workflows.
📊 Smart Contract Data Access
Enable on-chain logic to securely access paid, off-chain APIs—credit scores,
real-world events, IoT data.
🌉 Cross-chain DeFi
Move and manage USDC liquidity across EVM chains for composable finance
applications and multi-chain protocols.
pip install httpayerfrom httpayer import HttPayerClient
client = HttPayerClient()
response = client.request("GET", "http://provider.akash-palmito.org:30862/base-weather")
print(response.json()) # Automatic payment + data accessnpm install httpayer-tsimport { HttpayerClient } from "httpayer-ts";
const client = new HttpayerClient();
const response = await client.get("http://provider.akash-palmito.org:30862/base-weather");
console.log(response.data); # Seamless 402 handling# Python - Flask/FastAPI
from httpayer import X402Gate
@gate.gate
def premium_endpoint():
return {"data": "premium content"}// TypeScript - Express
import { X402Gate } from "httpayer-ts";
app.get(
"/premium",
x402Gate.gate((req, res) => {
res.json({ data: "premium content" });
}),
);HTTPayer is a modular, multi-language system designed for production use across multiple chains and environments.
🔧 Backend Services
- TypeScript Node.js Server: Orchestrates x402 payment flows, EIP-3009
signing, and 402 retry logic. Exposes
/httpayerendpoint for automated payment and resource fetching. - Python Treasury Server: Manages cross-chain USDC balances, gas estimation, and liquidity using Chainlink CCIP. Handles transfers, burn rates, and liquidity management.
- Facilitator Server: Chain-specific payment verification and settlement for multiple EVM chains.
- Demo Server: Real 402-gated endpoints for testing and demonstration.
📦 Developer SDKs
- Python SDK (
httpayer): Published to PyPI. IncludesHttPayerClientfor automatic payment handling andX402Gatedecorator for protecting Flask/FastAPI endpoints. - TypeScript SDK (
httpayer-ts): Published to npm. FeaturesHttpayerClientfor 402 handling in Node.js/browser andX402Gatemiddleware for Express.js, plus EIP-712/EIP-3009 signing utilities.
⛓️ Smart Contract Integration (Chainlink Functions)
HTTPayer leverages Chainlink Functions to bridge the gap between smart contracts and paid off-chain APIs. This serverless developer platform enables smart contracts to:
- Trigger HTTPayer Payments: Smart contracts can programmatically initiate x402 payments through the HTTPayer backend, enabling automated payment flows without manual intervention.
- Access Monetized Data: Consume valuable gated APIs that require payment,
including:
- Financial Data: Credit scores, bank balance proofs, financial attestations
- Real-World Events: Weather data, IoT sensor readings, sports results
- Enterprise Systems: ERP data, supply chain information, compliance records
- AI/ML Services: Model inference results, data analysis, predictions
How it Works:
- Smart contract makes a request to Chainlink Functions with API endpoint and payment parameters
- Chainlink's Decentralized Oracle Network (DON) executes the HTTPayer payment flow
- Each node independently fetches data and processes the payment via x402
- Nodes reach consensus on the result using OCR 2.0
- Final data is returned on-chain with cryptographic proof of authenticity
Key Benefits:
- Trust-Minimized: Decentralized execution ensures no single point of failure
- Secure Secrets: API keys and credentials are encrypted using threshold encryption
- Custom Computation: Transform and aggregate data before returning on-chain
- Gas Efficient: Offload complex computations to Chainlink's serverless infrastructure
This integration enables sophisticated use cases like parametric insurance, dynamic NFTs, automated trading strategies, and enterprise blockchain applications that require real-world data access.
🌐 Supported Networks
- Base Sepolia (testnet)
- Avalanche Fuji (testnet)
- Ethereum Sepolia (testnet)
- Easily extensible to mainnets and other EVM chains
🚀 Deployment All services are containerized and deployed to production. See backend documentation for live endpoints and setup instructions.
- HTTPayer Server: http://app.httpayer.com/httpayer
- Treasury Server: http://treasury.httpayer.com/treasury
- Facilitator Server: http://facilitator.httpayer.com
- Demo Server: http://provider.akash-palmito.org:30862
- HTTPayer Account Address: 0x6f8550D4B3Af628d5eDe06131FE60A1d2A5DE2Ab
- HTTPayer Consumer Smart Contract: 0x338937Ab9453eA2381c49C8b64E2dD2830915793
📋 Product & Strategy
PRD.md— Product requirements, user stories, success metrics, and strategic roadmapTODO.md— Current development priorities and project roadmap
🔧 Technical Documentation
backend/README.md— Backend setup, environment variables, API endpoints, and deploymentARCHITECTURE.md— System architecture, data flows, and integration patterns
📚 SDK Documentation
packages/python/README.md— Python SDK usage, examples, and API referencepackages/typescript/httpayer-ts/README.md— TypeScript SDK usage, examples, and API reference
🤝 Contributing
CONTRIBUTING.md— Setup instructions, coding standards, and contribution guidelines
MIT