Founding Engineer — Full-Stack

Sixtyfour builds AI research agents that discover, link, and reason over information about people and companies, transforming this intelligence into automated research workflows for sales, recruiting, and marketing. The Founding Engineer will build polished product experiences using Next.js and TypeScript, design backend APIs with FastAPI/Python, evolve the workflow engine, ship data pipelines, scale the AWS/Docker stack, and implement end-to-end product features, contributing to billing, permissions, and real-time UX.

Must Have

• Build polished, fast product experiences in Next.js + TypeScript (design-quality UI, accessible components, responsive layouts).
• Design clean backend contracts and APIs (FastAPI/Python) for workflows, jobs, billing, and auth.
• Evolve our workflow engine (DAG/state machine): scheduling, retries/idempotency, rate limits, progress tracking, logs, and user-visible run history.
• Ship data pipelines and background workers (Celery/queues), with strong observability and alerting.
• Scale and harden the stack on AWS + Docker (ECS/EKS or similar), with caching (Redis), pagination, backpressure, and cost controls.
• Implement product features end-to-end: DB schema → API → UI, including tests and telemetry.
• Contribute to billing (Stripe), permissions/RBAC, and realtime UX (SSE/WebSockets) for run status.
• Maintain a high bar for reliability, performance, and UX; instrument everything.
• Strong backend skills in Python (FastAPI preferred): API design, testing, error handling, schema/versioning.
• Experience deploying/operating with Docker and a major cloud (AWS preferred: ECS/EKS/Lambda, SQS, CloudWatch).
• Proven work on workflow/job systems: queues, retries, idempotency keys, scheduling, and run histories.
• Comfortable with Postgres (or MySQL) schema design and Redis (caching, rate limiting, locks).
• Performance mindset: RSC/Server Actions, data-fetching patterns, bundle/TTFB tuning, DB query perf.
• Production observability: logs, traces, metrics (e.g., Langfuse, OpenTelemetry, Sentry), and on-call pragmatism.
• Solid security hygiene (PII handling, secrets, JWT/session auth, CSRF/CORS, least-privilege access).

Good to Have

• Next.js App Router, RSC, Server Actions, edge/runtime primitives (Vercel/AWS CloudFront).
• Prisma/Drizzle; tRPC or GraphQL; Zod/JSON schema; feature flags/experimentation.
• Realtime UX (WebSockets/SSE), optimistic updates, background revalidation.
• Celery/RQ, event sourcing, or state-machine libs (e.g., Temporal, Dagster, Prefect, XState).
• Stripe (subscriptions, metered usage, webhooks) and customer-visible billing pages.
• CI/CD (GitHub Actions), IaC (Terraform), and basic cost/perf dashboards.
• Search/retrieval familiarity (OpenSearch/Elasticsearch) and simple relevance tuning.
• Testing: Playwright (e2e), Vitest/Jest, pytest; accessibility checks.

About Sixtyfour

We build AI research agents that can discover, link, and reason over everything about people and companies. The platform turns that intelligence into automated research workflows for sales, recruiting, and marketing.

About the role

What you’ll do

• Build polished, fast product experiences in Next.js + TypeScript (design-quality UI, accessible components, responsive layouts).
• Design clean backend contracts and APIs (FastAPI/Python) for workflows, jobs, billing, and auth.
• Evolve our workflow engine (DAG/state machine): scheduling, retries/idempotency, rate limits, progress tracking, logs, and user-visible run history.
• Ship data pipelines and background workers (Celery/queues), with strong observability and alerting.
• Scale and harden the stack on AWS + Docker (ECS/EKS or similar), with caching (Redis), pagination, backpressure, and cost controls.
• Implement product features end-to-end: DB schema → API → UI, including tests and telemetry.
• Contribute to billing (Stripe), permissions/RBAC, and realtime UX (SSE/WebSockets) for run status.
• Maintain a high bar for reliability, performance, and UX; instrument everything.

Minimum requirements

• Strong backend skills in Python (FastAPI preferred): API design, testing, error handling, schema/versioning.
• Experience deploying/operating with Docker and a major cloud (AWS preferred: ECS/EKS/Lambda, SQS, CloudWatch).
• Proven work on workflow/job systems: queues, retries, idempotency keys, scheduling, and run histories.
• Comfortable with Postgres (or MySQL) schema design and Redis (caching, rate limiting, locks).
• Performance mindset: RSC/Server Actions, data-fetching patterns, bundle/TTFB tuning, DB query perf.
• Production observability: logs, traces, metrics (e.g., Langfuse, OpenTelemetry, Sentry), and on-call pragmatism.
• Solid security hygiene (PII handling, secrets, JWT/session auth, CSRF/CORS, least-privilege access).

Nice to have

• Next.js App Router, RSC, Server Actions, edge/runtime primitives (Vercel/AWS CloudFront).
• Prisma/Drizzle; tRPC or GraphQL; Zod/JSON schema; feature flags/experimentation.
• Realtime UX (WebSockets/SSE), optimistic updates, background revalidation.
• Celery/RQ, event sourcing, or state-machine libs (e.g., Temporal, Dagster, Prefect, XState).
• Stripe (subscriptions, metered usage, webhooks) and customer-visible billing pages.
• CI/CD (GitHub Actions), IaC (Terraform), and basic cost/perf dashboards.
• Search/retrieval familiarity (OpenSearch/Elasticsearch) and simple relevance tuning.
• Testing: Playwright (e2e), Vitest/Jest, pytest; accessibility checks.

Technology

Language Models, Opensearch/Elasticsearch, Next.js (typescript), Python, FastAPI, AWS, Docker, Celery workers, Playwright, Supabase, Stripe