I’m upgrading my platform to process transactions through a dedicated blockchain gateway so every payment that passes through the system is cryptographically verifiable and tamper-proof. The job covers designing the gateway architecture, selecting an appropriate chain (Ethereum, Polygon, BSC or another you can justify), building or customising smart-contract code if that proves to be the simplest route, and exposing clean REST/JSON or Web3 interfaces my front-end can call. The core success metric is end-to-end security: a user initiates a payment on the site, the request reaches the gateway, the transaction is written on-chain, and I receive an instantly checkable hash I can surface back to the user. Performance must remain within normal web-app latency, and the code needs to be clean enough for a future audit. When you reply, focus on the secure-transaction gateways you’ve built or maintained, any chains or libraries you know inside out (web3.js, ethers.js, Hardhat, Truffle, Solidity, Golang, Rust, Hyperledger Fabric, etc.), and the challenges you solved around confirmations, gas optimisation, or key management. A concise outline of how you would approach this build will help me see whether your experience aligns with the project. Deliverables • Technical design and chain selection rationale • Smart contract or ledger code (if used) with tests • Gateway/API implementation ready for staging • Deployment scripts and step-by-step documentation I’m ready to start as soon as I find the right fit.