Senior Full-Stack Engineer

• Own features end to end across the gateway middleware, backend API, and frontend - including schema design, API contracts, UI, tests, and rollout.
• Build and operate the subscription and usage-based billing system, including payment provider integration, webhook reliability, usage-to-invoice mapping, and entitlement enforcement.
• Design and implement guardrails that inspect and enforce policy on LLM prompts and completions, with per-tenant configuration and full auditability.
• Extend the telemetry pipeline and analytics aggregations that power customer-facing cost and usage reporting, and add tracing, metrics, and alerting across services.
• Write middleware that runs in the live request path, treating latency, failure modes, and graceful degradation as first-class design concerns.
• Design multi-tenant data models with correct isolation between organizations, workspaces, and keys.
• Write meaningful automated tests for the code you ship.
• Participate in architecture decisions, code reviews, and planning; document decisions for a distributed team.
• Handle sensitive data responsibly - secret encryption at rest, least-privilege access, and audit logging.

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• 4+ years of professional full-stack experience, with genuine depth on both sides - you have owned production backend services and shipped non-trivial frontend features.
• Strong Python skills and experience building production APIs with FastAPI (or Django REST / Flask, with a willingness to work in FastAPI), including async programming.
• Strong React and TypeScript skills - comfortable with component-driven UI, SPA state management, routing, and integrating REST APIs including streamed responses.
• Payment system integration experience - Stripe strongly preferred, or a comparable provider (Paddle, Adyen, Braintree, Chargebee, Recurly). You have dealt with webhooks, idempotency, subscription lifecycles, proration, refunds, or usage-based/metered billing in production.
• Solid PostgreSQL skills: schema design, migrations, indexing, and query optimization - including aggregations over large event/log tables.
• Experience with multi-tenant architectures, authentication and authorization, and tenant data isolation.
• Comfortable with Docker and running services in Kubernetes; able to read a Helm chart and debug a failing pod.
• Experience with Redis or a comparable cache, and with designing for cache correctness and invalidation.
• Experience using AI-powered development tools (Cursor, VS Code with Copilot, or similar) and LLMs for research and problem-solving.
• Strong ownership and autonomy: able to take an ambiguous problem, propose an approach, and deliver it with minimal oversight.
• Clear written and spoken English for collaboration and documentation.

Nice to Have

• Practical experience integrating LLM APIs (OpenAI, Anthropic, Google, or similar) - streaming responses, token accounting, rate limits, retries, and cost awareness.
• Experience building guardrails, content moderation systems - or working on trust & safety, compliance, or security tooling.
• Familiarity with LLM gateways or proxies or with building an internal LLM platform.
• Experience with LLM observability and evaluation tooling and with building evaluation harnesses.
• Experience with usage metering and rating systems - turning high-volume event streams into accurate, auditable billable quantities.
• FinOps or cloud-cost-optimization background; experience showing customers where their money goes.
• Terraform and infrastructure-as-code experience on GCP (GKE, Cloud SQL, Secret Manager) or an equivalent cloud.

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