We are seeking an Integration Developer to build a containerised gateway service on AWS, using Node.js, TypeScript and Fastify on ECS Fargate. The service routes all transactional email from commerce and order management systems to a new email service provider. The developer will build:
•a pass-through API
•a backward-compatible API that converts legacy requests and responses using configurable mappings, so new campaigns can be added without a code release
The role covers idempotent processing, retry and failure handling, audit logging, event publishing and tracing, with security, resilience and observability built into the application. Development is OpenAPI-first, uses AI-assisted coding tools and is checked with contract tests built from real traffic. The developer will work closely with the architect, DevOps and QA on a fast build.
•Develop REST APIs in Node.js/TypeScript (Fastify or similar) to OpenAPI specifications, with request validation and structured error handling.
•Implement legacy auth/token emulation and request/response transformation for the backward-compatible API, without requiring consumer payload changes.
•Build configuration-driven campaign, field and error-code mappings using AWS AppConfig, supporting publisher and regional variants.
•Integrate securely with third-party email provider APIs using Secrets Manager credentials; implement safe error handling and PII-aware structured logging.
•Build idempotency with DynamoDB conditional writes, bounded timeouts, retry/backoff, circuit breaker and SQS/DLQ recovery, without changing the agreed API contract.
•Write audit records, publish events to EventBridge and propagate correlation IDs for end-to-end tracing.
•Use approved AI coding assistants to build mapping code, API specifications, unit tests and contract tests from sanitised discovery artefacts; review and correct every generated change.
•Support SIT, UAT, cutover and post-release stabilisation, including defect fixes and tuning.
Required Skills & Competencies
•Strong hands-on Node.js and TypeScript backend development, including Fastify (or a similar framework), asynchronous programming, REST/JSON APIs, validation and structured error handling.
•Working experience with AWS SDK integrations: DynamoDB, Secrets Manager, SQS/DLQ, and containerised deployment to ECS Fargate.
•Practical AI-assisted application development using an approved coding assistant: supplying contract context, iterating on generated code and verifying correctness with tests.
•API integration and transformation, legacy contract compatibility, token-based authentication and configuration-driven business mappings.
•Unit, API and contract-test development; Git-based peer review, CI/CD integration and production debugging using logs and distributed traces.
Idempotency, retry safety, timeout handling, circuit breakers and secure handling of credentials and personal data.
Good-to-Have
•AWS AppConfig, EventBridge, OpenTelemetry/ADOT, CloudWatch and X-Ray
•Jest or an equivalent TypeScript testing framework; Docker
•Java / Spring Boot exposure
