Backend Engineer - API & MCP

Role Overview

We are seeking a hands-on Senior Backend Engineer to design, build, deploy, and operate the API and MCP server that provide access to our factor library.

You will own the service architecture, library integration, authentication, licensing controls, documentation, and production reliability. Working closely with the factor-library team, you will translate supported capabilities into secure, consistent, and easy-to-use interfaces.

This role focuses on API and MCP engineering, with Python as the primary backend language.

Key Responsibilities

API and MCP Development

• Build and maintain production APIs using Python and FastAPI or a comparable framework.
• Develop an MCP server that enables compatible AI clients to discover and invoke supported factor-library capabilities.
• Define request and response schemas, input validation, error handling, and interface versioning.
• Build a shared integration layer to ensure consistent behaviour across the API and MCP server.
• Manage library execution, including blocking computations, concurrency, timeouts, and resource limits.
• Maintain compatibility as the factor library and client interfaces evolve.

Security and Access Management

• Implement authentication, secure credential handling, and organisation-level authorisation.
• Enforce client licensing and feature entitlements across API endpoints and MCP tools.
• Ensure each library invocation operates within the authenticated client's permissions.
• Implement appropriate request limits, audit logging, and protection of sensitive information.

Production Engineering

• Build automated tests covering library integration, interface behaviour, permissions, and failure scenarios.
• Containerise services and establish repeatable deployment, release, and rollback processes.
• Implement health checks, structured logging, metrics, monitoring, and alerts.
• Diagnose production incidents and improve service reliability, performance, and operating efficiency.
• Maintain operational documentation and troubleshooting procedures.

Developer Experience

• Produce API documentation, MCP tool descriptions, integration guides, and working examples.
• Document supported inputs, outputs, execution constraints, and error conditions with the factor-library team.
• Support client onboarding and resolve integration issues.
• Provide Python client utilities or a lightweight SDK where these simplify client adoption.

Required Technical Skills

• Python: Strong production programming skills, including type hints, exception handling, dependency management, and asynchronous programming.
• API engineering: Experience with FastAPI or a comparable Python framework, REST, HTTP semantics, JSON, schema validation, and OpenAPI documentation.
• Library integration: Experience exposing existing libraries or computational services through stable application interfaces.
• Concurrency and execution: Understanding of asynchronous I/O versus CPU-bound work, including when to use separate processes or background workers.
• Security: Practical experience with OAuth 2.0, token validation, API keys, secret management, and organisation-level access controls.
• Testing: Proficiency with pytest and automated integration tests, including permission checks and failure handling.
• Deployment: Hands-on experience with Docker, Linux, CI/CD, and at least one major cloud platform.
• Observability: Experience implementing logs, metrics, alerts, and production diagnostics.
• Engineering workflow: Proficiency with Git, code review, versioning, and controlled releases.

Required Experience and Attributes

• Demonstrated ownership of customer-facing APIs from design through deployment and ongoing operation.
• Experience supporting external developers and resolving production integration issues.
• Ability to make pragmatic architectural decisions and independently deliver maintainable software.
• Clear written communication and the ability to explain technical trade-offs.
• Willingness to remain hands-on across implementation, deployment, documentation, and support.

Preferred Qualifications

• Experience building MCP servers using the Python SDK and testing them with compatible clients.
• Familiarity with MCP tools, resources, remote connectivity, and authentication.
• Experience with AI tool calling, structured outputs, and permission-aware execution.
• Familiarity with Pydantic for request and response validation.
• SQL and PostgreSQL experience for client accounts, licensing configuration, and service metadata.
• Experience with Redis, background workers, or job queues for computational workloads.
• Experience building Python SDKs or other developer-facing libraries.
• Background in analytical software, financial technology, or institutional platforms.