Senior Software Engineer Engineering · London · On-site

We make it easy for developers and AIs to build on health data. Hundreds of wearables, sensors, labs, and health apps are connected, normalized, and made intelligent through a single platform. We process 15+ billion health data events per year. The health OS health data is fragmented; every device, app, and sensor speaks a different language. We built the health OS to solve that — a full-stack platform that turns raw, messy, siloed health data into something developers and AIs can reason over, build on, and ship with.

Terra was founded in 2021 and operates from London, San Francisco, and South Korea. We are funded by Y Combinator (W21), General Catalyst, Samsung NEXT, NEXT Ventures, and many of the world's finest investors. We are a team of engineers, researchers, builders, and designers. We hire people who get things done, think from first principles, and learn ferociously. We default to yes. We ship fast. We hack. We build. We don't do bureaucracy.

You will own and ship core platform systems that power how health data flows through Terra — from upstream data suppliers (wearables, health apps, sensors) into our unified schema, and out to downstream developers and AI consumers via our REST API, Streaming API, and webhooks. This is not a maintenance role. You will build new data connectors, scale real-time streaming pipelines, harden our authentication layer, and design the systems that handle millions of API calls per day. You will work across the entire stack — from low-level data ingestion to developer-facing API surfaces. You will ship fast, iterate through feedback loops, and think in first principles. We don't have layers of process. We have ownership and velocity.

What You Will Build

• Unified API & Data Normalisation: Design and extend the systems that ingest raw health data from 100+ upstream providers (Garmin, Fitbit, Oura, Apple Health, Google Fit, Withings, etc.) and normalise it into Terra's standardised schema.
• Upstream Data Supplier Connector: Architect and build Terra's new upstream connector capability, allowing data suppliers to push data directly into the platform.
• Streaming API: Scale our real-time streaming infrastructure for live sensor data (heart rate, steps, distance) from Apple Watch and BLE/ANT+ devices via websocket listeners.
• Authentication & Developer Experience: Own the authentication layer for both upstream suppliers and downstream developers.
• Webhooks & Event Delivery: Design and harden the webhook delivery system that pushes health data events to downstream consumers.
• Teams API: Contribute to our Teams API — enabling coaches, researchers, and organisations to aggregate and analyse group data across athletes, patients, and study participants.
• Health Scores & Derived Data: Build the backend systems that transform raw health metrics into validated scores backed by research.
• Infrastructure & Reliability: Maintain 99.5%+ uptime on a platform that processes billions of events.

What We Are Looking For

• 5+ years of production backend engineering experience.
• Deep API design experience.
• Strong with distributed systems.
• Proficiency in Python and/or Go.
• Database expertise.
• Cloud-native mindset.
• Security-first thinking.
• Autonomous and fast.
• High velocity, high standards.
• You are an athlete or obsessed with quantifying your own data.

How we work

• We are a high-velocity team.
• Skin in the Game: Everyone has equity.
• Deep Work: We protect focus time.
• Antifragile: We get stronger from chaos.
• Resourceful: We build with what we have and iterate relentlessly.
• Hackers: We build because we can't stop building.

By submitting this application, I agree that my personal data will be collected, processed, and retained by the company solely for the purposes of managing and assessing my candidacy.