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Comfy is an AI creation engine for visual professionals, built on an open-source workflow platform with 4 million users. The company provides a canvas-based interface for connecting AI models, processing steps, and outputs, used by artists, filmmakers, game studios, and major tech companies including OpenAI, Netflix, and Amazon Studios.
You will own the engineering behind Comfy's billing system, ensuring customers understand their spending and the company charges accurately as models, prices, and products evolve. This role spans the complete billing lifecycle: metering usage, collecting payments, managing credits and subscriptions, and protecting against financial abuse.
Key responsibilities:
- Build reliable usage metering for GPU compute and partner model APIs, handling delayed events, retries, and partial failures to ensure every billable event is recorded once and attributed correctly.
- Own the payment lifecycle: improve checkout, subscriptions, credit top-ups, plan and seat changes, prorations, refunds, and failed-payment recovery. Keep Stripe, Metronome, and application state consistent when events arrive late or systems fail.
- Reconcile charges, payments, and credits through automated checks across usage records, invoices, payments, and credit balances. Detect discrepancies, provide audit trails, and recover safely from partial failures.
- Build reusable pricing and entitlement systems for individual creators, teams, and enterprise customers, making new pricing models safe to ship without disrupting existing subscribers.
- Improve spend controls and detection of suspicious usage, payment fraud, and credit abuse. Work with Support and Finance on disputes and recovery while keeping legitimate usage smooth.
- Partner with product and frontend engineers on billing experiences and build tools for Support, Sales, and Finance to investigate charges and resolve issues.
The billing stack uses Go, PostgreSQL, Redis, Temporal, Stripe, and Metronome, alongside Python and Kubernetes across the broader platform. You will evolve an existing system, work across service boundaries, and take changes from design through production.
Comfy recently raised $30M at a $500M valuation, led by Craft with participation from Pace Capital, Chemistry, and TruArrow. The team is small and intense, based in San Francisco, with members from Stability AI and Google.
Requirements:
- Built and operated billing or payments systems in production with meaningful ownership of usage metering, credits, or consumption-based pricing.
- Integrated Stripe directly and worked through subscription changes, invoices, webhooks, and payment failures beyond the happy path.
- Can reason carefully about money across distributed systems: idempotency, concurrent updates, reconciliation, rounding, and recovery after partial failure. Can explain how you found and prevented a real billing error.
- Strong backend engineer with experience in relational data modeling and reliable APIs. Able to learn the stack and work across services to solve customer problems.
- Care about the experience behind the numbers. Can explain technical tradeoffs to Finance, Product, and Support and use their feedback to build better systems.
- Take ownership from problem definition through rollout and operation. Use AI development tools effectively and verify their output with the care that systems handling money require.
Bonus experience:
- Worked with Metronome, Orb, or similar metering platforms.
- Built durable workflows with Temporal.
- Billed GPU infrastructure or model APIs, tracked provider costs, or built systems for changing rate cards and per-request margins.
- Built spend limits or defenses against card testing, chargeback abuse, or trial and promotional-credit abuse.
- Improved international checkout, payment-method coverage, or payment authorization rates.
- Used ComfyUI, contributed to open source, or built tools for creative professionals.
