Backend Engineer (Python/ Django)

About the role

We are looking for a backend engineer who thinks before they build, designs systems as carefully as they write code, and takes ownership of what they ship. You will work on a large, business-critical Django platform that handles financial operations, client onboarding and the APIs behind our mobile and web products.

The platform is mature and performs well, and it has grown quickly. The next step is architectural: shaping it into a well-structured modular monolith, with clear boundaries between business domains, external integrations and shared services, while it keeps running in production. You will take on parts of that work end to end and ship features alongside the team.

Responsibilities

• Turn problems into written, phased implementation plans, agree them with the team, then deliver them phase by phase with a build tracker.
• Define and implement a modular architecture for a large Django codebase: business domains, integrations and shared services, each with a clear public interface that other modules use instead of reaching into its internals.
• Move models and code between Django apps in production with zero data loss and minimal downtime, planning database changes so that old and new code can run side by side.
• Consolidate external integrations into well-tested clients with consistent timeouts, retries, logging and safe handling of repeated callbacks.
• Put guardrails in place so the architecture holds: automated boundary checks in CI, tests around code before it is refactored, and clear conventions for new modules.
• Design and build REST APIs used by mobile and web clients, including authentication, protected actions and correct per-user data scoping.
• Design and tune background processing: queue routing, concurrency limits, and tasks that stay correct under retries and duplicates.
• Own deployments and production support for your areas, using metrics and logs to find root causes, not just symptoms.
• Review code and share knowledge with other engineers on design, testing and safe database changes.

 

Requirements

Python and Django

• 3+ years of professional Python, with at least 2 building and running production Django systems.
• Deep knowledge of the Django ORM: query optimization, avoiding N+1 queries, transactions and row locking (select for update).
• Django REST Framework: authentication (including JWT), custom permissions, throttling, and designing APIs that mobile clients depend on.

Problem solving, system design and planning

• You can take a vague problem, investigate it, and break it into a clear plan with phases, risks and trade-offs, and explain it in writing.
• Solid system design thinking: data modelling, consistency, concurrency, failure modes, and how a design behaves as load and data grow.
• Examples you can walk us through of problems you solved and systems you owned, including what went wrong and what you changed.

Architecture and refactoring

• Experience with, or a strong understanding of, modular design in Django: module boundaries, service interfaces, and keeping modules out of each other's internals.
• Understanding of safe database changes on live systems: expand/contract migrations and moving models between apps (for example with Separate Database and State).
• Refactoring incrementally, behind tests, while the system stays in production.
• Sound judgement on when to extract, when to consolidate, and when to leave working code alone.

Data, background jobs and infrastructure

• PostgreSQL: indexing, schema changes on large tables, and connection pooling.
• Celery and Redis: queue routing, retries, idempotent tasks, and knowing when work must run one at a time.
• Docker and Docker Compose, image-based deployments, and comfort working on Linux servers.
• Writing thorough tests with pytest, including for code that had none.

Integrations

• Integrating third-party systems of every kind: REST and SOAP APIs, direct database connections, and inbound webhooks and callbacks.
• Building integrations that move money correctly: idempotency, reconciliation, and handling providers that time out after completing the work.