Senior Backend Developer

We run a marketplace with over 300,000 active sellers and fulfillment centres in four regions. Since 1992, the company has expanded from listings into payments, shipping and seller financing.

The role:

This is a backfill for a team member who moved to another team. This hire will help us split a large monolith into a handful of well-defined services without breaking anything customers rely on. This is a long-term contractor role, paid monthly in USD. Our standups are at 9:00 AM Pacific. Day-to-day communication is in Slack and Google Meet.

Key responsibilities:

• Document APIs in OpenAPI and keep the docs current.
• Secure endpoints with OAuth 2.0, JWT validation and proper input checks.
• Coordinate with frontend and mobile engineers on API contracts and versioning.
• Tune slow queries, add indexes and read query plans.
• Design and build REST and gRPC APIs in Go, Java or Python.

What you need:

• 5+ years of backend development experience in a production environment.
• Familiarity with Docker and CI/CD pipelines.
• Experience designing and versioning HTTP APIs.
• Comfort reading logs, metrics and traces to debug problems in production.
• Strong SQL and relational data modelling skills.
• Understanding of concurrency, transactions, idempotency and retries.
• Hands-on experience with AWS, GCP or Azure services.

Preferred qualifications:

• NoSQL stores such as MongoDB, Cassandra or DynamoDB.
• Prior work breaking up a monolith.
• Background with high-volume payment or ledger systems.
• Kubernetes, including Helm charts.

Salary range: $2,400-$3,000 per month

Why work with us:

• Monthly payments via wire transfer or Wise.
• Paid time off.

The posting will close once we have a strong shortlist.

Shortlisted candidates will hear from us within two weeks.

Duration: 6 months. Start: Within 30 days.

Demo job created on 11jobs for testing and demonstrations. It is not an actual opening at Capstanline HQ.