Senior Platform & Backend Engineer – Python, AWS, Data APIs

Theia Insights; Greater London; Hybrid; GBP 75,000 - 110,000; Full time

Benefits offered by this job

EMI share options

25 days holiday + bank holidays

Private health insurance

Pension

Job summary

Theia Insights is building foundational financial intelligence products for institutional investors. This role focuses on producing reliable, scalable REST endpoints (FastAPI) and managing access to large datasets using Pandas, Parquet/Arrow and DuckDB.

You’ll own the identity layer (OAuth2, JWT, API keys) in a multi-tenant SaaS setup on AWS and contribute to data-facing services and occasional frontend work.

Qualifications

• Production-level Python development and operation experience.
• Experience shipping HTTP APIs with typed frameworks (e.g., FastAPI).
• Strong AWS experience with IAM, data services and least-privilege access.
• Experience with RBAC, multi-tenant SaaS architectures.
• Familiarity with data formats and analytics stacks (Parquet/Arrow, DuckDB, Pandas).

Responsibilities

• Build and operate async REST endpoints using FastAPI and Pydantic.
• Handle large datasets with Pandas, Parquet/Arrow and DuckDB.
• Own identity and access layer with AWS IAM, OAuth2/OIDC and API keys.
• Design APIs and data access points for analytics and MCP connectors.
• Run services on AWS (CDK, CodePipeline) and ensure reliability.
• Contribute to frontend TypeScript/React components when needed.
• Ensure end-to-end reliability and graceful failure modes.

Skills

Python production

FastAPI

OAuth2/OIDC

RBAC

JWT

API keys

Multi-tenant

Terraform

CDK

TypeScript

React

Tools

Pandas

Parquet/Arrow

DuckDB

AWS CDK

CodePipeline

S3

ECS/Fargate

Lambda

Job description

Theia Insights is building foundational financial intelligence products for institutional investors. This role focuses on producing reliable, scalable REST endpoints (FastAPI) and managing access to large datasets using Pandas, Parquet/Arrow and DuckDB.

You’ll own the identity layer (OAuth2, JWT, API keys) in a multi-tenant SaaS setup on AWS and contribute to data-facing services and occasional frontend work.