Veridian

Verdian is a decentralized, AI-powered content marketplace where creators can upload, price, and sell their written content (primarily markdown articles) as on-chain assets. It combines AI evaluation, blockchain tokenization, and a machine-to-machine payment protocol to create a fair, transparent ecosystem for digital knowledge.

On Verdian, when a creator uploads an article, an Evaluator Agent (powered by Google Gemini AI) analyzes the text and suggests a fair price in USDC along with keywords for discovery. The article is then tokenized on the Polygon Amoy testnet as a soulbound NFT, storing its keccak256 hash on-chain to guarantee content integrity and prevent duplicates.

Consumers—whether humans or autonomous agents—can discover articles via semantic keyword matching. If they request access, the Veridian Service enforces a blockchain-backed paywall by returning an HTTP 402 Payment Required response. The consumer completes payment through the x402 protocol (using signed EIP-712 payloads with USDC), and upon verification, the full content is unlocked.

The system demonstrates:

AI-driven valuation → fair, dynamic pricing for written content.

Soulbound tokenization → immutable, non-transferable proof of content existence and authorship.

x402 paywall protocol → standard HTTP payment enforcement with on-chain receipts.

End-to-end agentic flows → a demo client autonomously discovers, pays for, and accesses content.

Built for ETHGlobal New Delhi 2025, Verdian showcases how AI and blockchain can merge to build a sustainable content economy where knowledge is both discoverable and fairly monetized. It’s a working MVP with a frontend for creators, a unified backend for content/payments, an AI microservice for evaluation, and demo agents for automated purchasing.

Veridian is built as a microservices architecture using Node.js/Express for backend services, React/Vite frontend, and Solidity smart contracts on Polygon Amoy. The Evaluator Agent uses Gemini AI for content pricing and keyword extraction, while the Veridian Service handles content storage with SQLite/Prisma and enforces x402 cryptographic payments. These services communicate via HTTP APIs, with the frontend providing upload/marketplace interfaces. The x402 protocol integration enables seamless paywall enforcement, and a demo client script orchestrates the complete discovery-to-purchase flow. Notable hack: heuristic fallback pricing when AI is unavailable.