Backend / API Engineer (Platform, Data, & Live Services)

Backend / API Engineer (Platform, Data, & Live Services) 40–60 hours per month initially, heavier during the platform handover and the Unity front-end transition, then gradually settling into a growth and support role. $55–$80 per hour, depending on experience. Long-term, ongoing role with growing responsibility. We are building a consumer-facing mobile brain-health product that blends habit formation, interactive systems, and character-led conversational experiences, all wrapped in an immersive, game-like world. We are now moving the entire front-end of the app into that world, rebuilt in Unity, sitting on top of an established backend platform. That backend is the source of truth for accounts, goals, progression, subscriptions, content, and chat, and it is the single surface everything the new Unity front-end is built against. We’re looking for a Backend / API Engineer to own that platform end to end: to take it in-house, harden it, and turn it into the stable, well-documented, well-tested system our Unity developer builds the new experience on top of. This role is NOT for someone who wants to spin up a quick CRUD API and hand it off, or who only enjoys greenfield projects. You will be inheriting a real production system and making it clean, reliable, and yours. This role IS for someone who likes owning the backbone: taking an existing platform, understanding it deeply, and becoming the person the rest of the team confidently builds against. It is a slightly crazy opportunity at the edge of innovation, working with an extensively-connected, world-renowned team of neurologists, marketers, public health advocates, designers, and developers. CORE RESPONSIBILITIES PLATFORM OWNERSHIP & IN-HOUSE TRANSITION Take full ownership of our existing Django 4.2 / Django REST Framework service, currently maintained by an external agency, and bring it in-house cleanly. Absorb the handover: map the architecture, document it, and remove any blocking dependency on the outgoing agency Own the AWS deployment: containerised services on ECS, with an automated CI/CD pipeline (merge to staging triggers a build and deploy) Keep the REST API as the single source of truth for accounts, goals, progression, subscriptions, chat, and app data Own backend reliability, uptime, observability, and cost API DESIGN FOR THE UNITY FRONT-END Be the person who hands our Unity developer every system they need to rebuild the front-end from live data. You provide the server surface; they build the world. Design, document, and version the API contracts the Unity client is built against Own the authentication and token flow (JWT access and refresh) the client uses to prove identity, and keep endpoints secure Own and evolve the Unity data and asset endpoints (including the existing get / post / delete proxy layer to the Unity services) Provide a consolidated bootstrap payload for first sign-in and app startup — account, progression, entitlements, goals, content and configuration returned in a single call, so the client is not stitching together a large number of requests to become usable Publish clear contracts, mock endpoints, and an OpenAPI spec so the Unity build can proceed in parallel without waiting on the backend Be a responsive, well-documented, dependable surface: the backend should never be the thing blocking the front-end GAME & SESSION SERVICES The product includes a set of brain games built in Unity. You own the server side of those games — the contracts and the data — while the Unity developer owns the gameplay and the scoring implementation itself. Own the session lifecycle APIs: what the client receives when a game launches, and what it submits when a session ends Persist and serve results, scores, session history, and per-user progression and difficulty state Serve game configuration from the backend so difficulty curves, parameters, and content can be tuned without a client release Connect game outcomes to the wider economy and progression systems (points, streaks, rewards, entitlements) so the world responds consistently to what the player does CONVERSATIONAL & CHARACTER SERVICES (BACKEND SIDE) Our characters are the face of the product’s intelligence. A separate AI Systems Engineer owns how they behave; you own the service that carries them. Own the Django service, APIs, and persistence behind the conversational layer, including conversation and message history Own streaming/transport so responses arrive incrementally and feel live in the Unity client Own the structured action and event schemas the client consumes, co-defined with the AI Systems Engineer and versioned like any other contract Own the infrastructure, scaling, latency, and failure behaviour of that layer REAL-WORLD / GEOSPATIAL DATA LAYER Build and own the backend for the real-world map experience, where the world reflects locations near the user. Our current direction is a self-hosted, open-data approach on PostGIS with H3 spatial indexing; the architecture should stay flexible enough that we can swap providers or components later without forcing major client-side changes. Serve proximity-based queries and behaviourally-relevant nearby locations to the client within tight performance budgets Own enrichment, caching, filtering and prioritisation of place data, and management of data density in busy areas Integrate and curate open place data into a spatial database (PostGIS), self-hosted to avoid vendor lock-in Keep provider-specific detail behind a stable contract, so a change of data source is a backend change, not a client rebuild DATA, SUBSCRIPTIONS & INTEGRATIONS Own the data model, migrations, and data integrity Own subscription and entitlement logic, including server-side validation of in-app purchase receipts, so tiers are enforced on the server and not just trusted from the client Own push notification delivery (Firebase Cloud Messaging) and lifecycle / webhook integrations to our marketing and community tools Extend our existing Django and community platform setup for social features, rather than standing up a separate parallel system Support real-time or near-real-time updates where the experience needs them TESTING, RELEASE SAFETY & RELIABILITY A single client now depends entirely on this API, so breaking a contract quietly is the most expensive mistake available to us. We want that made structurally difficult. Build automated API, integration, and contract testing, with particular rigour around the Unity-facing surface Own migrations with a credible rollback path, so a bad deploy is recoverable rather than an incident Own monitoring and alerting, and keep staging a genuine rehearsal for production rather than a formality Version and deprecate endpoints deliberately, giving the client a window rather than a surprise HOW THIS ROLE FITS THE TEAM We keep three ownership lines deliberately clear so nothing falls in the seams between them: Backend / API Engineer (this role) — platform, APIs, accounts, data, progression, subscriptions, social and community integrations, map and enrichment services, infrastructure, and providing a dependable server surface AI Systems Engineer — AI behaviour and orchestration: routing, prompts, retrieval, guardrails, evaluations, model behaviour and reliability, and AI cost management Unity Developer — the complete client and front end, the games, world and gameplay implementation, client-side integration, and platform builds In practice that means you own what the server knows, stores, and returns; the AI Systems Engineer owns what the characters decide and say; and the Unity developer owns everything the user sees and touches. Where those meet — most obviously in structured actions, game session contracts, and the bootstrap payload — the contract is co-defined, documented, and versioned. CROSS-FUNCTIONAL COLLABORATION You will work closely with: Our Unity developer, who builds the front-end against the endpoints, contracts, and data you provide Our AI Systems Engineer, whose agent logic runs inside your service Product, content, and clinical teams, for whom you expose the data and controls they need REQUIRED SKILLS Strong, production-grade Python, Django, and Django REST Framework Comfort taking over and hardening an existing or inherited codebase, not only building from scratch AWS experience, specifically containerised deployment (ECS) and CI/CD pipelines (CodeBuild or similar) API design and versioning for native or third-party clients (you will be serving a Unity / C# client, so clean, well-documented contracts matter) Token-based authentication and endpoint security (JWT, access / refresh flows) Relational data modelling with PostgreSQL, and confidence with migrations Automated testing discipline: API, integration, and contract tests as a normal part of shipping, not an afterthought A clear communicator who can hand a documented API to a non-backend teammate and explain technical decisions to a non-technical team BONUS SKILLS Geospatial work: PostGIS, H3 or similar spatial indexing, proximity and points-of-interest systems, and familiarity with map data providers such as Mapbox or open-data equivalents Experience serving APIs to game engines or Unity clients, including session, progression, and live-configuration patterns Working familiarity with Unity and with Blender / 3D asset pipelines — you do not need to be a Unity or Blender developer, but understanding how the 3D client, assets, and interactive systems work makes collaboration and integration far easier Streaming responses over HTTP or WebSockets to non-web clients Asynchronous and background processing (Celery with SQS, or similar) In-app purchase and subscription receipt validation (Apple and Google) Experience carrying a system through an agency-to-in-house transition Health-, education-, or behaviour-change products WHAT SUCCESS LOOKS LIKE After the first 1–2 months: The platform is fully in our hands, with no blocking dependency on the outgoing agency, and deploys are understood and reliable The Unity team has a documented, stable API to rebuild the front-end against, with no guesswork Bootstrap, authentication, and subscriptions are enforced server-side and behave predictably After 3–4 months: The API is a durable, extensible asset: new games, features, tiers, and the real-world map layer can be added without re-architecture Contract tests catch breaking changes before the client does Backend reliability and cost are predictable and observable The Unity front-end transition is never blocked on the backend side