Python Developer
First seen by Alion on Sep 22, 2026.
Role : Python / FastAPI Backend Engineer - API Migration
Experience : 6 - 12 years
Role Overview :
We are looking for experienced Python Backend Engineers to work on an API migration initiative. The role involves migrating existing REST APIs from a Nuclio/Iguazio serverless environment to Python + FastAPI microservices running on Kubernetes, while maintaining functional and API contract parity with the existing services.
The engineer will work closely with the technical lead, QA, client SMEs, and platform teams to understand existing implementations, migrate business logic, integrate with existing backend systems, and validate the migrated services.
Key Responsibilities :
- Analyze existing Nuclio-based REST APIs, handlers, business logic, and dependencies.
- Migrate API business logic to Python/FastAPI microservices.
- Maintain functional and API contract parity with existing services.
- Work with existing shared libraries/SDKs and FastAPI frameworks.
- Integrate APIs with backend systems and data stores.
- Implement request validation, error handling, authentication/entitlement logic, and API transformations.
- Develop unit and integration tests for migrated services.
- Perform API contract and functional validation against existing services.
- Troubleshoot application, integration, and performance issues.
- Participate in code reviews, technical discussions, and design reviews.
- Prepare API/OpenAPI documentation and operational handover documentation.
- Follow established coding, CI/CD, security, and development standards.
Required Technical Skills :
1. Must Have :
- Strong experience in Python backend development.
- Hands-on experience with FastAPI or similar Python REST frameworks.
- Strong understanding of REST APIs, API contracts, JSON/XML, HTTP methods, and status codes.
- Experience developing microservices and migrating/refactoring existing applications.
- Strong understanding of unit and integration testing using frameworks such as PyTest.
- Experience working with one or more databases such as MongoDB, Cassandra, Elasticsearch / Solr, or SQL/NoSQL databases.
- Experience with asynchronous programming/concurrency in Python.
- Good understanding of Docker and Kubernetes environments.
- Experience with Git-based development and CI/CD pipelines.
- Strong debugging and problem-solving skills.
2. Good to Have :
- Experience with Nuclio, Iguazio, V3IO, or other serverless platforms.
- Experience working with Kafka/event-driven architectures.
- Experience with NFS/HDFS/S3 or distributed file systems.
- Experience with API gateways such as Kong.
- Experience with authentication, authorization, RBAC, or entitlement frameworks.
- Experience with performance testing and API benchmarking.
- Experience with observability, logging, metrics, and distributed tracing.
- Experience working with OpenAPI/Swagger.
- Exposure to AI-assisted software development and code migration tools.
Migration-Specific Skills :
The candidate should be comfortable with :
- Understanding an existing codebase and documenting its behavior before migration.
- Identifying hidden dependencies and legacy behavior.
- Translating serverless handlers into layered FastAPI services.
- Preserving existing API contracts and business rules.
- Comparing legacy and migrated API responses.
- Creating automated tests to establish functional parity.
- Working with multiple backend dependencies within a single service.
- Supporting phased migration and parallel development across multiple services.
Soft Skills :
- Strong communication and collaboration skills.
- Ability to work directly with client technical SMEs.
- Ability to independently analyze legacy applications and identify dependencies.
- Strong ownership of assigned services from assessment through integration testing.
- Comfortable working in an outcome-driven delivery model.
- Ability to proactively identify technical and schedule risks.
Skills
Python, Backend Architecture, REST API, SDK, FastAPI, SQL, NoSQL, API Gateway, Distributed Systems, OpenAPI