Software Engineer: Platform and Backend (Mid-career / Senior)

About The RoleTheia Insights builds foundational financial intelligence products, including industry classification, knowledge graphs and factor risk models, for institutional investors. We serve some of the largest asset managers, hedge funds, index providers and sell-side banks.As an engineer on the Platform team you'll productise our data and build the ways customers access and work with it. You'll own the analytical services, APIs and MCP connectors that let customers query our data directly from the tools they already use, and build first-party applications powered by our data.What You'll DoBuild and operate async REST endpoints (FastAPI, Pydantic) that serve large datasets reliably and quicklyWork with large tabular data in pandas, Parquet/Arrow and DuckDB, and manage the memory and performance trade-offs of moving big datasets efficientlyOwn the identity and access layer, including AWS technologies for identity, authorisation and data distribution, supporting access to data through multiple channelsDesign and build new access points for our data, such as APIs, analytical services and MCP connectorsRun services on AWS, with infrastructure in AWS CDK shipped via CodePipelineProductionise code from the data and quantitative teamsOccasionally contribute changes to Theia Insights' TypeScript/React frontends that consume our API, particularly where a feature is simplest to own end to endTake end-to-end ownership of reliability and performance, including graceful handling of failure modesRequirementsEssentialStrong production Python including experience shipping and operating servicesHTTP APIs in a typed framework such as FastAPI, with schema and contract disciplineProduction AWS: S3, a compute service (e.g. ECS/Fargate or Lambda) and a datastore, with least-privilege IAMUsefulAuth in production: OAuth2/OIDC, JWT validation, API keys, scopesTabular data at scale: pandas plus Parquet/Arrow, ideally DuckDBMulti-tenant SaaS: RBAC, API-key managementNice to haveInfrastructure as code (CDK in TypeScript, or Terraform)React/TypeScript, or comfort in a polyglot repoLLM or MCP integration and AI-facing toolingFinancial-data or regulated-environment backgroundExperience We're Looking ForWe care more about what you've owned than years on a CV. A strong mid-level engineer who has shipped and operated production AWS services, owning one end to end with tests, will meet the bar. Senior candidates will likely have designed large scale systems, owned responsibilities for auth or multi-tenant access, made cross-region and disaster-recovery trade-offs, and set the standard for a team.BenefitsCompetitive salary plus EMI share options25 days holiday + bank holidaysPrivate health insurance, pensionHybrid working in UK from London or Cambridge