Summary / TL;DR
Responsibilities WaaS provider integration: integrate WaaS provider APIs to implement wallet address management, multi-chain asset consolidation, and the full withdrawal/payout flow Co-signer risk controls: build the callback handler that enforces whitelist checks, limit controls, and frequency detection before automated signing Webhook processing: build a highly reliable on-chain event ingestion service covering signature verification, idempotent deduplication, and exception compensation Internal ledger: design and maintain user balance ledgers, consolidation records, and master-account reconciliation to keep funds data strongly consistent Consolidation scheduling: implement smart consolidation driven by threshold triggers, scheduled jobs, and low-gas-window strategies Fee estimation: integrate rate APIs and exchange market data to implement dynamic multi-chain fee conversion Edge-case handling: handle high-risk scenarios such as AML interception, insufficient gas, missed webhooks, and failed merchant callbacks Ops tooling: support manual-intervention features in the ops console (manual consolidation, deposit backfill, chain activation, etc.) Requirements Bachelor's degree or above in computer science or a related field 5+ years of Java backend development experience; proficient with Spring Boot / Spring Cloud Hands-on experience shipping crypto payments or Web3 projects (crypto pay-in/pay-out, wallet systems, on-chain asset management, etc.) Solid understanding of blockchain fundamentals: UTXO vs. account models, on-chain confirmations and finality, gas/miner fee mechanics Strong webhook engineering experience with the ability to independently design idempotency schemes Strong MySQL schema design skills — able to independently design ledger-style tables and familiar with funds-flow record standards Distributed systems experience: distributed locks, transaction boundaries, and eventual consistency Nice to Have Hands-on experience with WaaS provider SDKs / APIs Understanding of MPC (multi-party computation), HSM, or private-key custody mechanisms Built asset consolidation scheduling or gas management systems Familiarity with AML / KYT compliance integration Experience with traditional acquiring/payment systems Familiarity with AWS architecture
