Node.js Blockchain Backend Build

I’m launching a new web application and need the entire server-side built in Node.js. Instead of a traditional data store I want every persistent operation—create, read, update, delete—to be recorded on-chain, so the solution must integrate directly with a public or side-chain blockchain that you recommend (Ethereum, Polygon, or another EVM-compatible network).

Your task begins with setting up a clean Node.js codebase (TypeScript preferred), then designing smart-contract or on-chain schemas that can act as our data layer. From there you’ll expose a well-documented REST or GraphQL API that my front-end team can consume, including wallet-based authentication, JWT session handling, and robust error management.

Deliverables
• Node.js project scaffold pushed to my private repo
• Smart contracts (or equivalent) deployed to a testnet and verified
• API endpoints wired to those contracts, each covered by unit tests and collected in a Postman/Swagger file
• Clear README with local setup, testnet deployment and production hand-off instructions

I’ll review the work against the test suite and the API documentation, so everything listed above must pass before hand-off is complete. Experience shipping blockchain-backed Node.js services is a must; picking the right libraries—Express, NestJS, Fastify, ethers.js, web3.js—is up to you as long as the end result is clean, secure, and easy to maintain.