Senior/Staff Software Engineer, Core Product

About this role

This is a founding role on the small team that owns fal's core product systems — the connected tissue the whole business runs on: usage, billing, pricing, accounts, access, API keys, and model discovery. You'll join early, own these systems end-to-end (from data model through rollout to operational health), and design the APIs and product surfaces other teams and customers depend on. These are backend systems where correctness underpins real revenue and customer trust.

You will inherit systems that are functional, but you'll own their evolution over time to meet our growing customer needs and scale. Your first priority will be billing, fraud, and pricing. These are our highest-impact business initiatives, directly affecting both customer experience and revenue. From there, you'll expand your ownership across accounts, access and identity, API keys, and model discovery.

If you enjoy building and evolving high-impact platform systems that directly influence both our customers' experience and the effectiveness of our internal teams, this is the place to be.

What you'll do

• Own billing and pricing first — metering, usage roll-ups, pricing logic, and the customer/admin surfaces that make cost understandable and trustworthy.

• Design APIs, data models, and product contracts other teams safely build on.

• Grow into the broader portfolio — accounts, access/identity, API keys, and model discovery — and the surfaces that expose usage, cost, and access.

• Engineer for correctness and resilience: source of truth, idempotency, auditability, permissions, observability, graceful failure.

• Own operational health, including on-call for the systems you build.

• Partner across product, infra, finance, revenue, security, and customer-facing teams — turning messy, manual workflows into durable systems.

Qualifications/Nice to have:

• 5+ years building reliable, production backend systems (Python and/or TypeScript).

• Strong PostgreSQL — schema design, queries, migrations, performance.

• API & data-model design for complex product or business domains.

• Can ship product and internal surfaces in React / Next.js / TypeScript.

• Strong systems judgment (source of truth, idempotency, auditability, permissions, observability) and product judgment (workflows, edge cases, customer trust).

• Thrives in ambiguous, cross-functional work where product, business logic, and infra overlap; ships a pragmatic v1 that can evolve. Priorities move fast — you're comfortable with that.

• Usage-based billing / metering / pricing — Stripe, Orb, Metronome, or similar.

• Identity & access — permissions, SSO, API keys, org/account hierarchy.

• Developer platforms, model registries, or usage/observability dashboards.

• Generative AI / inference APIs or other developer-facing AI products.

• We use Python (primary backend) · TypeScript + React/Next.js (product surfaces) · PostgreSQL / SQL · with some migration to Rust underway.

What fal offers

• Interesting and challenging work

• A lot of learning and growth opportunities

• We offer visa sponsorship and will help you relocate to San Francisco.

• Health, dental, and vision insurance (US)

• Regular team events and offsites

Compensation

• $180,000 - $250,000 + equity + comprehensive benefits package