William Silva

I build an AI/RAG solution for researching tax collections and preparing answers with traceable sources and expert validation. • I design and implement the backend in TypeScript, Node.js, and NestJS using Clean Architecture and DDD. I integrate a third-party document API and legacy databases through an API-first approach. • I built a hybrid-search and adaptive-retrieval pipeline over about 12.9 million Apache Solr documents, 1.2 million legacy SQL Server queries, and Cassandra data, combining lexical and vector search, embeddings, chunking, reranking, deduplication, and semantic caching. • I integrated OpenAI and AWS Bedrock with model orchestration, agents, tool calling, and cost-based routing. I implemented structured responses, guardrails, grounding, citation verification, and automated evaluation. • I reduced answer preparation from approximately 1.5–2 days, with an SLA of up to 72 hours, to a 1-minute median. The solution reached about 95% alignment with consultant answers and reduced manual effort by approximately 50%. After improving state-level content retrieval, the error rate on ICMS questions fell from about 50% to under 3%. • I structured REST APIs and asynchronous workers with Redis, BullMQ, and RabbitMQ, applying idempotency, retries with backoff, DLQs, and message deduplication. • I added logs, cost and latency metrics, and per-stage traces with OpenTelemetry and CloudWatch. I created more than 650 unit tests with Jest and configured CI/CD with GitHub Actions, Docker, and Kubernetes. Technologies: TypeScript, Node.js, NestJS, OpenAI, AWS Bedrock, LangChain.js, Apache Solr, SQL Server, Apache Cassandra, Redis, BullMQ, RabbitMQ, OpenTelemetry, CloudWatch, Swagger/OpenAPI, Docker, Kubernetes, GitHub Actions, and Jest.

Developed and evolved a multitenant SaaS platform for supply chain and foreign trade, progressing internally from Junior III Full Stack Software Engineer to Mid-Level Software Engineer I. • Developed a real-time query chatbot for about 30 partner companies, integrating multiple databases and reducing manual searches from hours to seconds. • Built saved charts, maps, Portuguese and English internationalization, and AI interfaces with React and Next.js. Created a shared design system that reduced rework when developing new features. • Evolved the architecture and security with DDD, Clean Architecture, SOLID, OAuth2/OIDC, and permission-based access control, strengthening isolation between accounts and services. • Implemented BrasilAPI, Stripe, and Pagarme integrations with normalization, pagination, caching, retries, rate limiting, and circuit breakers. Also optimized PostgreSQL queries through indexes and execution-plan analysis. • Implemented asynchronous integrations with Kafka, SQS, and SNS and AWS services with ECS, EC2, and Lambda. Configured IAM permissions, Grafana monitoring, and build and deployment pipelines with Docker and GitHub Actions. Technologies: TypeScript, Node.js, NestJS, Next.js, React, GraphQL, PostgreSQL, TypeORM, Kafka, Amazon SQS, Amazon SNS, Docker, GitHub Actions, and AWS.

Developed e-commerce products for Mercado Livre and Shopee sellers. • Designed and implemented four microservices with TypeScript, Node.js, NestJS, Express, and Fastify, using RabbitMQ for asynchronous communication. • Integrated Mercado Livre and Shopee APIs into a solution used by more than 150,000 sellers across Latin America, applying pagination, batch processing, caching, and rate-limit control for large volumes of listings. • Modeled and optimized persistence across PostgreSQL, Firebird, MongoDB, Redis, and Firebase by creating indexes, analyzing execution plans, and tuning critical queries. • Standardized AWS and GCP build and deployment pipelines with Docker and GitHub Actions. • Developed and published a React Native app integrated with the platform APIs. Coordinated a three-developer team, assigned tasks, and followed code reviews and tests with Jest and SuperTest. Technologies: TypeScript, Node.js, NestJS, RabbitMQ, PostgreSQL, Firebird, MongoDB, Redis, Jest, SuperTest, React, React Native, Docker, AWS, GCP, and GitHub Actions.

Worked as a freelance web developer, delivering websites and applications on demand for clients across different industries. • Built responsive interfaces with HTML, CSS, JavaScript, and React, turning business needs into clear, functional experiences. • Implemented frontend features, API integrations, and usability and performance improvements. • Fixed bugs and delivered ongoing maintenance for existing projects. • Managed projects end to end, from requirements and scope definition to client communication, version control, and delivery. Technologies: JavaScript, TypeScript, React, HTML, CSS, Git, and REST APIs.