PromptPay copy
Pay-per-prompt AI marketplace: connect your wallet, grant one spend permission, then pay only for the prompts you send via automatic on-chain micro-payments.
Videos
Description
PromptPay is a pay-per-prompt AI marketplace that replaces subscriptions and API keys with a single wallet connection.
Users grant a one-time ERC-7715 spend permission, then send prompts that are paid for automatically via x402 on-chain micro-payments settling fractions of a cent per request in the background, with no transaction to sign each time.
Prompts run on Venice AI for privacy-first inference, and payments are relayed gaslessly through the 1Shot permissionless relayer on Base. The result is a frictionless, usage-based way to access AI: pay only for what you actually use, no commitments, no key management, no recurring fees.
Progress During Hackathon
<p>We designed and built PromptPay end-to-end during the hackathon, going from concept to a working pay-per-prompt AI marketplace.</p><ul><li><p><strong>Architecture & planning</strong>: Mapped the full system: wallet, ERC-7715 spend permission, x402 micro-payment , Venice AI inference, with the 1Shot relayer handling gasless settlement on Base Sepolia.</p></li><li><p><strong>Frontend</strong>: Built the Next.js 14 app: landing page, prompt interface, wallet connect, a permission gate for granting the one-time spend allowance, result panel, and transaction history.</p></li><li><p><strong>Payments</strong>; Implemented the x402 client/server flow so a protected API returns <code data-inline="true" spellcheck="false">402 Payment Required</code>, the client auto-settles the micro-payment, and the prompt proceeds, no per-prompt signing.</p></li><li><p><strong>Permissions</strong>: Integrated ERC-7715 spend permissions via wagmi + MetaMask SDK so users grant a budget once.</p></li><li><p><strong>AI integration</strong>: Wired up the Venice AI API for privacy-first, OpenAI-compatible inference behind the paid endpoint.</p></li><li><p><strong>Relayer</strong>: Connected the 1Shot permissionless relayer (EIP-7710) for gasless, USDC-paid transactions.</p></li></ul><p>By the end we had a functional flow: connect wallet, grant permission once, prompt and auto-pay per request.</p>
Tech Stack
Fundraising Status
<p>None</p>