Pay For API 🚀

Pay-per-call AI APIs using Celo stablecoins. No subscriptions. No credit cards. Just pay what you use.

🌐 Live Website: payforapi.online | 🎥 Demo Video: YouTube | 🏆 Karma Profile: KarmaHQ | 🌟 Talent Protocol: Talent.app

🌍 Supported Stablecoins

Token	Currency	Price Per Call
USDm 🇺🇸	US Dollar	$0.001
EURm 🇪🇺	Euro	€0.001
KESm 🇰🇪	Kenyan Shilling	KES 0.13
BRLm 🇧🇷	Brazilian Real	R$0.005
GHSm 🇬🇭	Ghana Cedi	GHS 0.01
COPm 🇨🇴	Colombian Peso	COP 4.00
PUSO 🇵🇭	Philippine Peso	₱0.056

🤖 Available APIs

API	Endpoint	Price
Weather Info	/api/weather	0.001 USDm
Global News	/api/news	0.002 USDm
Crypto Pulse	/api/crypto	0.001 USDm
AI Summary	/api/summary	0.005 USDm
AI Translate	/api/translate	0.003 USDm
Image Gen	/api/image	0.01 USDm

📱 Multi-Wallet & MiniPay Integration

• Universal Web3 Access: Full support for WalletConnect, MetaMask, Rabby, and Coinbase Wallet via RainbowKit/Wagmi.
• Seamless MiniPay Support: Auto-detects window.ethereum.isMiniPay for Opera Mini browser users.
• Auto-connects wallet — no popups
• Uses USDm as feeCurrency for all transactions
• Discovery manifest: /.well-known/minipay.json
• Hook: hooks/useMiniPay.ts

🚀 Quick Start

npm install
cp .env.example .env.local
# Fill in your API keys and contract addresses
npm run dev

📋 Celo Onchain Agents Hackathon

Built for the Celo Onchain Agents Hackathon (May 22 - June 15, 2026)

• Track 1: Best Agent on Celo
• Track 2: Most Onchain Activity
• Track 3: Highest 8004scan Rank

🛠️ Developer SDK (@pay-for-api/sdk)

The Developer SDK allows autonomous agents to seamlessly interact with x402 endpoints. By providing an EVM-compatible private key, the SDK automatically handles 402 Payment Required interception.

Installation

npm install @pay-for-api/sdk

Usage Example

import { PayForApiClient } from '@pay-for-api/sdk';

const client = new PayForApiClient({
  privateKey: process.env.CELO_PRIVATE_KEY
});

// The fetch call automatically handles x402 invoice settlement in the background
const response = await client.fetch('https://pay-for-api.com/api/weather');
const data = await response.json();

📈 Creator Dashboard (List Your Own API)

Pay For API is not just a consumer platform; it is a two-sided marketplace. Developers can register their own Web2 or Web3 endpoints via our Creator Dashboard.

How it Works:

1. Register: Submit your endpoint URL and desired USDm price per call.
2. Wrap: Our platform provides a reverse-proxy x402 wrapper.
3. Earn: Every successful call routes payment directly to your Celo wallet.

Smart Contract Revenue Split

Earnings are managed by the APIRevenueSplitter.sol contract. - 90% routes to the API Creator instantly. - 10% routes to the Pay For API Treasury to sustain infrastructure.

📚 Comprehensive Developer Guide

Welcome to the deep-dive documentation for Pay For API.

1. Architecture Overview

The platform follows a highly modular architecture separating the frontend, backend middleware, and Celo smart contracts.

1.1 Frontend Stack

Built with Next.js 15 App Router, React 19, and Tailwind CSS v4 for a highly responsive, glass-morphic UI.

1.2 Wallet & Provider Integration

We utilize ethers.js v6 for provider interactions, specifically auto-detecting the MiniPay injected provider via window.ethereum.isMiniPay.

1.3 Smart Contracts

All smart contracts are written in Solidity 0.8.24 and compiled using Hardhat. They handle API revenue splits and APIC token logic.

1.4 x402 Middleware

Our Next.js API routes are protected by custom x402 middleware that intercepts requests and validates on-chain payment hashes.

2. Environment Setup & Configuration

Before running the project locally, you must configure a series of environment variables.

• NEXT_PUBLIC_RPC_URL: The Celo Mainnet RPC URL used for public data reading.

• PRIVATE_KEY: The deployer's private key used for smart contract deployments and backend admin transactions.

• OPENAI_API_KEY: Required for the Premium AI Chat endpoint.

• GEMINI_API_KEY: Required for the AI Summary and AI Translate endpoints.

• WEATHER_API_KEY: Sourced from OpenWeatherMap for real-time meteorological data.

• NEWS_API_KEY: Used to fetch global news headlines for the News API endpoint.

3. Smart Contract Deployment Guide

To deploy the contracts to the Celo network, ensure your wallet is funded with CELO for gas.

3.1 APICredits.sol

This contract implements the ERC20 standard with additional minting logic for daily rewards and streaks.

3.2 APIRevenueSplitter.sol

Handles the 90/10 split between API creators and the platform treasury.

Run the deployment script using Hardhat: ash npx hardhat run scripts/deploy.ts --network celo

3.3 Contract Verification

Verify your deployed contracts on CeloScan using the @nomicfoundation/hardhat-verify plugin.

ash npx hardhat verify --network celo <DEPLOYED_CONTRACT_ADDRESS>

4. API Endpoint Reference

Detailed specifications for each premium endpoint offered on the marketplace.

4.1 POST /api/chat

Accepts a user message and returns an AI-generated response. Requires a xHash proving a 0.005 USDm payment.

4.2 GET /api/weather

Requires a lat and lon query parameter. Returns current weather data. Price: 0.001 USDm.

4.3 GET /api/news

Returns the top 10 global news headlines. Price: 0.002 USDm.

4.4 GET /api/crypto

Fetches live prices for major cryptocurrencies including BTC, ETH, and CELO. Price: 0.001 USDm.

4.5 POST /api/summary

Accepts a long text payload and returns a concise AI-generated summary. Price: 0.005 USDm.

4.6 POST /api/translate

Accepts text and a target language code. Returns translated text. Price: 0.003 USDm.

5. x402 Protocol Deep Dive

The x402 protocol is the backbone of Pay For API's monetization strategy.

5.1 HTTP 402 Payment Required

When a client accesses a premium endpoint without a valid payment, the server returns an HTTP 402 status code.

5.2 Invoice Generation

Along with the 402 status, the server provides an invoice containing the required token address, amount, and recipient.

5.3 Payment Settlement

The client's wallet processes the payment on the Celo network and obtains a transaction hash.

5.4 Transaction Validation

The client retries the request, including the transaction hash in the X-Payment-Hash header. The server verifies this hash on-chain before serving the data.

6. MiniPay Integration Guide

MiniPay is an ultra-lightweight wallet built into the Opera Mini browser, designed for users in emerging markets.

6.1 Auto-Detection

Our platform uses window.ethereum.isMiniPay to seamlessly detect the wallet and bypass standard connection modals.

6.2 Gas Abstraction (FeeCurrency)

All transactions are formatted to use USDm as the eeCurrency, ensuring users don't need native CELO to pay for gas.

6.3 Transaction Formatting

MiniPay strictly requires Legacy (Type 0) or EIP-1559 (Type 2) transactions. We ensure all ethers.js transactions are correctly populated.

7. Security Best Practices

Maintaining the integrity of the marketplace and protecting user funds is paramount.

7.1 Rate Limiting

All API endpoints are protected by IP-based rate limiting to prevent abuse and DDoS attacks.

7.2 Double-Spend Prevention

The backend maintains a registry of processed transaction hashes to ensure a single payment cannot be used multiple times.

7.3 Input Sanitization

All user inputs, especially for AI prompts and database queries, are strictly sanitized to prevent injection attacks.

7.4 Smart Contract Audits

The APICredits and APIRevenueSplitter contracts have undergone internal review, though external audits are recommended before high-volume mainnet usage.

8. Creator Dashboard Overview

The Creator Dashboard empowers developers to monetize their own endpoints on our platform.

8.1 Endpoint Registration

Creators provide their endpoint URL, metadata, and set a custom USDm price.

8.2 Gateway Routing

Pay For API acts as a reverse proxy, enforcing x402 payments before routing the request to the creator's server.

8.3 Analytics & Earnings

Creators can track their total calls, revenue generated, and withdraw their 90% share directly to their Celo wallet.

9. Future Roadmap

We are constantly iterating and expanding the capabilities of Pay For API.

9.1 Multi-Chain Expansion

While Celo is our native home, we plan to support x402 payments on Base, Optimism, and Arbitrum.

9.2 Decentralized RPC Integrations

Integrating with decentralized infrastructure providers to ensure 100% uptime for our middleware gateways.

9.3 Subscription NFTs

Introducing optional NFT-based monthly passes for users who prefer bulk access over pay-per-call. - 10% routes to the Pay For API Treasury to sustain infrastructure.

📚 Comprehensive Developer Guide

Welcome to the deep-dive documentation for Pay For API.

1. Architecture Overview

The platform follows a highly modular architecture separating the frontend, backend middleware, and Celo smart contracts.

1.1 Frontend Stack

Built with Next.js 15 App Router, React 19, and Tailwind CSS v4 for a highly responsive, glass-morphic UI.

1.2 Wallet & Provider Integration

We utilize ethers.js v6 for provider interactions, specifically auto-detecting the MiniPay injected provider via window.ethereum.isMiniPay.

1.3 Smart Contracts

All smart contracts are written in Solidity 0.8.24 and compiled using Hardhat. They handle API revenue splits and APIC token logic.

1.4 x402 Middleware

Our Next.js API routes are protected by custom x402 middleware that intercepts requests and validates on-chain payment hashes.

2. Environment Setup & Configuration

Before running the project locally, you must configure a series of environment variables.

• NEXT_PUBLIC_RPC_URL: The Celo Mainnet RPC URL used for public data reading.

• PRIVATE_KEY: The deployer's private key used for smart contract deployments and backend admin transactions.

• OPENAI_API_KEY: Required for the Premium AI Chat endpoint.

• GEMINI_API_KEY: Required for the AI Summary and AI Translate endpoints.

• WEATHER_API_KEY: Sourced from OpenWeatherMap for real-time meteorological data.

• NEWS_API_KEY: Used to fetch global news headlines for the News API endpoint.

• NEXT_PUBLIC_WALLETCONNECT_PROJECT_ID: Required for RainbowKit multi-wallet support (get from cloud.walletconnect.com).

3. Deployed Smart Contracts

Our smart contracts are deployed and verified on the Celo Mainnet:

• APICredits (APIC): 0x486776B119aAf9eEe3c215D0e42d9Aa426A76b80 Implements the ERC20 standard with additional minting logic for daily rewards and streaks.

• APIRevenueSplitter: 0x5ac6de9FAe3f424C7f07C65283B8953108aa5C78 Handles the 90/10 split between API creators and the platform treasury.

• CommunityNFT: 0x0D2238a8E6a2c5951E6cBeb8e03278f5d0C8FFB6 A community membership NFT rewarding consistent API consumers.

4. Smart Contract Deployment Guide

To deploy the contracts to the Celo network, ensure your wallet is funded with CELO for gas.

Run the deployment script using Hardhat:

npx hardhat run scripts/deploy.ts --network celo

Verify your deployed contracts on CeloScan using the @nomicfoundation/hardhat-verify plugin.

npx hardhat verify --network celo <DEPLOYED_CONTRACT_ADDRESS>

5. API Endpoint Reference

Detailed specifications for each premium endpoint offered on the marketplace.

4.1 POST /api/chat

Accepts a user message and returns an AI-generated response. Requires a xHash proving a 0.005 USDm payment.

4.2 GET /api/weather

Requires a lat and lon query parameter. Returns current weather data. Price: 0.001 USDm.

4.3 GET /api/news

Returns the top 10 global news headlines. Price: 0.002 USDm.

4.4 GET /api/crypto

Fetches live prices for major cryptocurrencies including BTC, ETH, and CELO. Price: 0.001 USDm.

4.5 POST /api/summary

Accepts a long text payload and returns a concise AI-generated summary. Price: 0.005 USDm.

4.6 POST /api/translate

Accepts text and a target language code. Returns translated text. Price: 0.003 USDm.

5. x402 Protocol Deep Dive

The x402 protocol is the backbone of Pay For API's monetization strategy.

5.1 HTTP 402 Payment Required

When a client accesses a premium endpoint without a valid payment, the server returns an HTTP 402 status code.

5.2 Invoice Generation

Along with the 402 status, the server provides an invoice containing the required token address, amount, and recipient.

5.3 Payment Settlement

The client's wallet processes the payment on the Celo network and obtains a transaction hash.

5.4 Transaction Validation

The client retries the request, including the transaction hash in the X-P