I already have fully designed mobile and web front-ends; what I’m missing is the engine behind them. Your task is to build a production-ready backend that powers a multi-currency wallet, exposes a clean API, and gives me an administrator console I can actually run the business from. Wallet core The service must let every user check their balance, browse an accurate transaction history, and send or receive cryptocurrency with on-chain confirmation. Speed and reliability are paramount, so efficient queueing and retry logic will be essential. Public API I need a REST/JSON (GraphQL is fine if you can prove the advantage) layer that provides secure user authentication, up-to-the-minute cryptocurrency exchange rates, and full transaction processing. Token-based auth, rate-limiting, and thorough input validation are non-negotiable. Please document the endpoints in Swagger or an equivalent tool so my front-end team can plug straight in. Administrator control panel Inside the control panel I want granular user management, searchable audit logs, and live system monitoring so I can see node health, memory usage, and pending jobs at a glance. A simple Help / FAQ editor will round out the console so I can update guidance without touching code. Data should flow in real time where possible, and every admin action must be captured for compliance. Security & deployment Harden everything with 2FA, role-based permissions, cold-wallet protocols, and automated backups. Containerised deployment scripts (Docker or Kubernetes) will make it effortless for me to spin up staging and production environments. Deliverables • Complete backend source code with unit tests • Database schema and migration files • Swagger/Postman collection for every endpoint • Admin panel modules: wallet, users, audit, monitoring, help • Docker/K8s configs plus setup instructions • Final walkthrough and 30-day bug-fix grace period Acceptance criteria: wallet actions return in under two seconds on testnet, 100 % of endpoints are documented, and every admin click lands in the audit log. If this sounds like your kind of build, let’s talk timelines and milestones.