I want to run my own standalone cryptocurrency payment gateway—no plug-ins or hosted third-party services. The system must let me generate payment requests, monitor them in real time, and confirm settlement across several chains. Supported coins and networks • Bitcoin (BTC) • Ethereum (ETH) • TRON tokens (TRC-20) • SOL (Solana) • TON • Any BEP-20 asset Core features • Real-time transaction tracking with automatic status updates and webhooks • Multi-currency handling that creates unique deposit addresses, detects incoming funds, and normalises confirmations across chains Technical expectations – Clean REST/JSON API so my websites or mobile apps can create a charge, query its status, and receive callbacks. – Secure key management: hot wallet for day-to-day processing plus an easy way to move funds to cold storage. – Clear documentation, from install to integration, ideally with Docker or similar one-command deployment. – Lightweight admin panel or CLI to view transactions, balances, and logs. Deliverables 1. Full source code (language/framework is your call, but reliability and maintainability come first). 2. Deployment script and environment sample. 3. README covering API endpoints, authentication, and security considerations. 4. Short hand-over session to walk me through setup and best practices. If you have previous blockchain or gateway builds to showcase, link them in your bid so I can gauge code quality and security focus. To enhance payment flexibility and global accessibility, we plan to integrate native cryptocurrency payment functionality into our website. The system will connect directly to each blockchain’s native RPC nodes—avoiding third-party gateways—to ensure security, control, and alignment with decentralized principles. 1. Supported Blockchain Networks The following blockchains and their respective assets are supported: - Bitcoin (BTC): Native BTC transfers - Ethereum (ETH): ERC-20 tokens (e.g., USDT, USDC) - BNB Smart Chain (BSC): BEP-20 tokens (e.g., USDT-BSC) - TRON: TRC-20 tokens (e.g., USDT-TRC20) - Solana: SPL tokens (e.g., USDC, USDT) - TON (The Open Network): Native TON and Jetton tokens 2. Core Functional Requirements 2.1 Deposit Address Pool Management Admins can manually or in bulk import deposit addresses into an address pool for each supported asset via the admin panel. When a user initiates a deposit, the system randomly assigns an available address from the corresponding pool. Each assigned address has a time-limited validity (default: 30 minutes). If not used within the timeframe, it is automatically released back into the pool. The system monitors all addresses in the pool uniformly, improving performance and reducing node load. 2.2 Real-Time Transaction Monitoring & Confirmation The system uses native RPC endpoints (via polling or subscription) to monitor on-chain transactions. It detects and validates incoming transfers (amount, recipient address, confirmation count). Once confirmed, the user balance is updated and the frontend is notified. 2.3 Automated Fund Aggregation (Cold Wallet Sweeping) After successful deposits, funds are automatically swept from used addresses to a main/cold wallet. Aggregation rules (thresholds, intervals) are configurable. Gas or energy fees are handled automatically, with optional auto-top-up when needed. 2.4 Withdrawal Management Support withdrawals of both native coins and tokens from the main wallet to external addresses. A multi-level approval workflow is implemented based on withdrawal amount (e.g., manual review for large amounts). Transaction status is tracked and recorded, with links to blockchain explorers. 2.5 Data Synchronization & Reconciliation All on-chain transactions are stored in the local database with full audit logs. The system supports filtering, searching, CSV export, and real-time fiat value conversion using exchange rate APIs (USD, CNY, etc.). 2.6 Security & Risk Control Private keys must be stored offline and never exposed in code, logs, or environment variables. Critical operations (signing, sweeping) should be performed using MPC, HSM, or isolated signing servers. Role-based access control (RBAC) and approval workflows are enforced for sensitive actions. 2.7 High Availability Architecture Asynchronous tasks (monitoring, sweeping, alerts) are processed via message queues such as Redis + BullMQ. The system includes retry mechanisms, failure recovery, and alerting through Slack or email to ensure reliability. 3. Technical Implementation Requirements - No reliance on third-party services (e.g., Infura, Alchemy, TronGrid). All connections must use public or self-hosted full-node RPCs. - Officially recommended SDKs per chain: - Bitcoin: bitcoinjs-lib + bitcoind - Ethereum / BSC: ethers.js or web3.js - Tron: tronweb - Solana: @solana/web3.js - TON: ton, ton-core All private key handling must occur in secure, isolated environments. Production systems must never contain plaintext keys. 4. Frontend & Admin Integration 4.1 User-Facing Frontend Integration The payment feature will be seamlessly integrated into the existing frontend interface. Users see the assigned deposit address, QR code, countdown timer, and real-time status updates. The UI supports multiple languages (English, Chinese) and responsive design across devices. 4.2 Admin Management Console The backend management interface is built with Ant Design (antd) and React, and will be integrated into the current admin platform. Key modules include: - Address Pool Management: View, add, remove, and monitor address status (idle, assigned, expired) - Deposit Records: Search and filter by chain, time, status; export data to CSV - Aggregation Settings: Configure sweep rules and view execution logs - Withdrawal Approval Center: Review, approve, or reject withdrawal requests - Monitoring Dashboard: Display real-time metrics and charts (inflows, success rates, asset distribution)