Senior Backend Engineer

Full-Stack Developer (Freelance) — Manufacturing Execution System

Steel pipe manufacturer. Sole developer on a greenfield MES, end to end.

• Designed, built, and deployed a production-grade MES from scratch as the sole developer — architecture, backend, frontend, database, mobile, deployment, and production support.
• Modelled complex manufacturing workflows across 20+ production stages, translating shop-floor processes into scalable software.
• Architected backend services in Go with relational data models covering production tracking, quality control, inventory, and manufacturing traceability.
• Designed RBAC authorization and workshop-based data partitioning to enforce operational security and process ownership.
• Delivered web admin portals, operational dashboards, reporting, and Android shop-floor apps, with real-time KPI monitoring, defect analysis, and equipment status reporting.

Senior Java Software Engineer

Enterprise SaaS commerce platform. Owned search and promotion infrastructure for 20,000+ merchants.

• Search & promotion platform. Co-architected a distributed Elasticsearch platform indexing 60M+ SKUs across multiple indices on a 32-node cluster serving 20K+ merchants.
• Scaled write throughput to ~10K writes/sec from Kafka consumers via asynchronous batch commits, shard-level parallelism, and optimized indexing pipelines — cutting data lag from 1–2 hours to under 30 minutes during Double 11 and 618 peak campaigns.
• Sustained 500K+ QPS on the read path through hot/cold data separation, index_sort, filter-only queries, and dynamic replica scaling up to 128 replicas.
• Resolved critical write failures caused by the 2.1B doc-per-node limit via routing redesign, and enforced cluster guardrails plus nightly force_merge.
• Search reconciliation platform. Built a distributed reconciliation system from scratch keeping MySQL and Elasticsearch near real-time consistent — a 3-level diff engine (field, scope, and document count), a pluggable rule engine, non-blocking multi-source loaders over Dubbo, self-healing repair with exponential-backoff retries, and full audit logging with message replay.

Senior Java Software Engineer

Used-car trading SaaS platform for automotive dealers across China; listed on NASDAQ in 2026.

• Led development of the Vehicle Product Center platform serving 40,000+ automotive businesses.
• Designed configurable workflow and business-rule automation inspired by Salesforce Flow, letting non-technical users define event-driven processes without code changes.
• Developed a metadata-driven rule engine on Elasticsearch, Redis, MySQL, and Painless scripting.
• Built scalable backend services and APIs supporting product lifecycle management and tenant-specific customization.