Founding Backend Engineer

About the Company

At Heart Mind Talent, we’re partnering with an exciting, fast-growing AI music startup to bring on exceptional talent.

Imagine a world where everyone around you creates music – together, in real time. That’s the future this team began building just six months ago. Since then, over 100k+ users have created more than 1M+ songs – from shower singers to seasoned artists, including producers behind global names like A$AP Rocky. Their platform empowers creators to turn ideas into professional-grade music in seconds, with as much control as they want.

Backed by $7M+ in funding from leading investors, this is a team on a mission to make music creation as universal and engaging as music listening.

They’re a small, talent-dense group based in London, operating with high ownership, rapid velocity, and low-ego collaboration. Think specialist generalists who work hard, learn fast, and ship relentlessly. This is a team that cares deeply about what they’re building and is in it for the long run.

About the Role

As the product scales, so does the need for a robust backend. You’ll play a key role in building the foundation that supports growth from 100k users to millions. This includes designing relational schemas, leading the migration from non-relational systems, and ensuring payments, media delivery, and deployment are reliable at scale.

This role is ideal for someone who thinks in data models, cares about production reliability, and ships with both speed and discipline.

What You'll Do

• Drive the full migration from Non-Relational to Relational Database. Canonical relational schema design, migration strategy, dual-writes, backfills, reconciliation, and zero-data-loss cutover
• Design clean REST APIs for high concurrency, real-time collaboration, and cross-platform clients (web + mobile)
• Own the payments backbone end-to-end. Stripe + RevenueCat. Web-hooks, entitlement reconciliation, edge-case coverage (upgrades, downgrades, refunds, cross-platform parity), and automated billing tests
• Build reliable media upload, processing, and delivery at scale. Signed URLs, CDN caching strategy, transcoding pipelines with retries and observability
• Set up and own deployment and operational excellence. Better CI/CD with staged deploys and rollbacks, structured logging, tracing, SLOs, and alerting tied to user impact
• Keep media streaming reliable and evolve it into a reusable platform capability, including text and audio streaming
• Establish the backend primitives for real-time collaboration and high concurrency as we move toward multiplayer features

What We're Looking For

• Strong relational schema design. Deep SQL experience with normalisation, indexing, migrations, and schemas that hold up as the product and team grow
• Database migration experience. Can plan and execute a zero-data-loss migration to a relational database, including backfills, reconciliation, and rollback
• API design for high concurrency. Designs clean APIs with idempotency, pagination, rate limiting, retries, and safe versioning. Thinks in contracts that work across web, mobile, and future clients
• Payments and entitlements integrity. Has built or owned a payments backbone where revenue state and entitlements are always correct. Stripe and RevenueCat experience strongly preferred
• Production ownership mindset. Strong instincts for failure modes, graceful degradation, incident response, and rollback discipline
• DevOps and deployment. Docker, CI/CD, sane environments. Makes deploys repeatable and safe for the whole team
• Media pipeline experience. Upload, processing, and fast global delivery via signed URLs and CDN caching. Understands media-heavy performance bottlenecks
• First-principles thinker. You challenge what doesn't make sense, but stay humble and update your thinking when new evidence appears
• Ownership + high velocity + low ego. You care about outcomes after release, not just merges. You ship fast and do whatever it takes for the team

Nice-to-Haves

• Experience with search-oriented databases (e.g., ElasticSearch) or vector databases (e.g., ChromaDB) for text and semantic search
• Real-time foundations with WebSockets, SSE, or CRDT/collaboration-aware system design
• Server-side rendering knowledge (e.g., Next.js) to support the frontend team during migration
• Experience with analytics and logging pipelines (e.g., PostHog, Axiom, or more enterprise-ready options)