Senior Software Engineer - Remote (Costa Rica)

About the role

NeoEvolution AI is hiring a Senior Software Engineer for a 100% remote, long-term independent contract with a large US-based client. The engineer owns the source of truth for care-provider organizations, locations, users and permissions behind a B2B loyalty platform used by tens of thousands of aesthetics practices. Candidates must be based in Costa Rica and work overlapping US business hours.

Key responsibilities

• Own the user, role and organization domains and build and evolve the APIs and SDK contracts consumed by other teams.
• Migrate logic from older serverless and GraphQL services into NestJS domain services without breaking dependents.
• Protect data integrity through lifecycle automation driven by SAP data (archival, transfers), backfills, reconciliations and large account migrations.
• Review roughly 35-65% of the team's pull requests and lead cross-team design of consumer SDKs, user APIs, data integrity and authentication, writing RFCs and migration plans.
• Keep the platform healthy through runtime upgrades, CI hardening, test infrastructure and performance tuning.

Required profile

• 5+ years of software-engineering experience, with substantial backend work.
• Clear written and spoken English, including RFCs and migration plans other teams can act on.
• Nice to have: Terraform, Kubernetes (Kustomize overlays, IRSA), Datadog, GitHub Actions and ArgoCD.

Required skills

• TypeScript and Node.js at production depth, including NestJS.
• In-depth PostgreSQL: schema design, migrations, indexing and EXPLAIN ANALYZE, with TypeORM.
• AWS serverless and event-driven design: Lambda, SQS (including FIFO and dead-letter queues), SNS and Parameter Store.
• REST with OpenAPI and typed SDKs, plus GraphQL for older services.
• Authentication and authorization: role-based access, Okta, service-to-service auth via a central IAM and DPoP.
• Testing with Jest and integration tests backed by Testcontainers.