Senior Backend Python Developer - FastAPI & Microservices - Freelance

Context

We are supporting a technology company operating a large-scale digital platform in an international environment, with strong engineering challenges around scalability, reliability, API design and product delivery.

The engineering team is strengthening a business-critical backend domain that supports external partner integrations and core operational workflows.

The consultant will join an established product-engineering team as a fully integrated member, contributing to both technical modernization and new product capabilities. This is not an isolated delivery assignment: the role requires strong collaboration, ownership and the ability to understand business challenges behind technical decisions.

Mission – Key Responsibilities

Legacy Modernization & Microservices Migration

• Contribute to the progressive extraction of business capabilities from a legacy Django monolith into existing Python microservices.

• Help define clean service boundaries, migration strategies and reliable integration patterns between legacy and distributed services.

• Improve maintainability, scalability and fault tolerance across backend systems.

• Participate in technical design, implementation, code reviews and migration delivery as part of a collaborative engineering team.

Backend Engineering & Public APIs

• Design, develop and optimize backend services in Python, using frameworks such as Django, FastAPI or equivalent.

• Build and evolve secure, reliable and well-documented public APIs used by external partners.

• Improve API usability through cleaner contracts, versioning strategies and new integration capabilities.

• Work on business-critical flows involving operational data updates, permissions, eligibility rules and partner-facing services.

• Ensure data consistency and robustness across distributed and transactional workflows.

Tech Stack

• Backend: Python, Django, FastAPI

• Architecture: Legacy monolith extraction, microservices, distributed systems, public APIs

• Databases: PostgreSQL, BigQuery

• Cloud: GCP, Pub/Sub, Cloud Run

• CI/CD & Infrastructure: GitHub Actions, Docker, Kubernetes

• Observability: Datadog, Sentry

• Additional Topics: Workflow orchestration, DAGs, LLM integrations, AI-enabled backend processes

Profile

• 7+ years of experience in backend engineering, with strong expertise in Python.

• Significant experience working on complex product architectures in demanding, high-scale environments.

• Proven experience contributing to a monolith-to-microservices migration, ideally involving a Django legacy environment.

• Strong understanding of API design, versioning, reliability and external integration challenges.

• Comfortable working on distributed systems, data consistency and business-critical backend flows.

• Experience with cloud-native environments, CI/CD, monitoring and production operations.

• Exposure to workflow orchestration, DAGs or AI/LLM-powered backend use cases is a strong plus.

• Product-oriented mindset, with the ability to understand functional needs beyond pure technical implementation.

• Collaborative approach: comfortable working collectively on shared priorities rather than owning topics in isolation.

• Fluent English required.