Samson A.

Backend & API Integrations Engineer — Java/Spring Boot, Node.js/NestJS, and the third-party integrations most teams don't want to touch (QuickBooks, Xero, payments, accounting). I build and stabilize reliable backends: clean REST APIs, microservices, and integrations that actually stay in sync. 8+ years of backend experience and 2,700+ hours delivering systems that handle high traffic and financial/inventory workflows. Where I help most: - API & platform integrations — QuickBooks Online & Xero (OAuth2, tokens, webhooks, sync, reconciliation), cXML purchase-order flows, and payment/accounting platforms - Microservices — designed and maintained 32+ services with CI/CD + Docker, improving uptime and cutting deployment time - Backend rebuilds — refactored legacy systems into scalable services with measurably higher throughput - Security — JWT, Spring Security, and Auth0 authentication/authorization - Reliability — async processing with Kafka/SQS, idempotency, retries, and rate limiting, backed by tests (JUnit, Mockito, Testcontainers) Tech I work with: Java, Spring Boot, Node.js, NestJS, Python, PostgreSQL, MySQL, MongoDB, MariaDB, Redis, DynamoDB, Docker, Apache Kafka, AWS SQS, REST, gRPC. How I work: I start with a short review of your current code/architecture, then give you a clear plan, timeline, and checkpoints — so you always know what's happening and what comes next. If you're dealing with a fragile backend, a stalled integration, or you need a new API built right the first time, send me a message describing what you're trying to achieve and I'll reply with a concrete next step. — Samson