Senior Backend Engineer

Remote or Hybrid | Full-time Contract (8 weeks, possibility of permanent or monthly rolling) | Immediate Start

About the Role

We are building a high-growth consumer technology platform and are looking for a Senior Backend Engineer to join a small, fast-moving team. You will own the backend architecture, lead API development, and work directly with the product owner and other engineers to ship a production-ready platform on a tight deadline.
This is a hands-on role, required to write code. You will also make architectural decisions, enforce engineering standards, and take full ownership of the backend from development through to production deployment.

If you are the kind of engineer who thrives in early-stage builds, takes pride in clean and well-tested code, and wants to be part of something significant from the ground up — this is for you.

What You Will Be Doing

• Designing and building scalable REST API endpoints using Node.js and TypeScript

• Managing database schema design and migrations with PostgreSQL

• Owning the payment integration layer — webhook handling, transaction flows, and payout logic

• Building and maintaining asynchronous job queues for delivery workflows

• Setting up and maintaining CI/CD pipelines and cloud deployments

• Enforcing code quality standards — TypeScript strict mode, linting, and test coverage

• Reviewing pull requests and mentoring where needed

• Writing unit and integration tests for all critical business logic — especially payments and authentication

What We Are Looking For
Must have:

• 4+ years of backend development experience with Node.js

• Strong, demonstrable experience with TypeScript in a production environment

• Production experience with PostgreSQL and a modern ORM

• Experience building and securing REST APIs — token-based authentication, role-based access control, rate limiting, and input validation

• Solid understanding of Redis for caching, session management, and background job queues

• Experience integrating payment gateways and handling payment webhooks in production

• Familiarity with Docker and container-based deployments

• Strong understanding of security fundamentals — common vulnerability categories, secret management, and webhook signature verification

• Experience working in a monorepo environment

Strong advantage:

• Previous experience as a technical lead or senior engineer in an early-stage startup

• Familiarity with Nigerian payment infrastructure and local market payment flows

• Experience with framework-level backend architecture decisions — not just implementation

• Abuja-based candidates will be given preference for hybrid working arrangements

How to Apply
Only applications submitted by email to info@gaininfinity.com will be considered. Applications received through any other channel will not be reviewed. We move fast. Shortlisted candidates will be contacted within 5 business days. Only candidates who follow the application instructions exactly will be considered.
Send your application to info@gaininfinity.com with the subject line:

Senior Backend Engineer Application

Your email must include all three of the following. Incomplete applications will not be considered:
1. Your CV

2. GitHub or code sample from a real production project — not a tutorial or practice repository. We will read it.

3. Answer to the question below. Write no more than one paragraph. Do not use bullet points.

Question. You have a payment webhook handler running in production. Late one evening, your monitoring shows that three orders have been marked as paid, but no receipts were issued and the payment provider confirms the money was received. Walk us through exactly what you do in the next 30 minutes.

Job Types: Full-time, Contract

Contract length: 8 weeks

Work Location: Hybrid remote in Abuja
Application Deadline: 25/04/2026