Software Engineer - Full-Stack at Sixtyfour (X25)

14 Minutes ago • All levels • $100,000 PA - $200,000 PA

Full Stack Development

Job Description

Sixtyfour builds AI research agents that discover, link, and reason over data about people and companies, transforming this intelligence into automated research workflows for sales, recruiting, and marketing. The platform is a data orchestration engine enriching detailed datapoints from public and proprietary sources, enabling enterprise customers to build custom data pipelines to find, enrich, qualify, and act on company-specific requirements for people and business data. The mission is to power how enterprises understand and act on people and companies with world-class intelligence.

Good To Have:

Experience with Next.js App Router, RSC, Server Actions, and edge primitives.
Familiarity with Prisma/Drizzle, tRPC/GraphQL, Zod/JSON schema, feature flags.
Knowledge of Realtime UX (WebSockets/SSE) and optimistic updates.
Experience with Celery/RQ, event sourcing, or state-machine libraries.
Proficiency in testing frameworks like Playwright, Vitest/Jest, pytest.

Must Have:

Build polished, fast product experiences using Next.js and TypeScript.
Design clean backend contracts and APIs with FastAPI/Python.
Evolve the workflow engine for scheduling, retries, and tracking.
Ship data pipelines and Celery background workers with strong observability.
Deploy stack on AWS + Docker, managing caching, pagination, and cost.
Implement product features end-to-end from DB schema to UI.
Maintain high reliability, performance, and UX standards.
Demonstrate strong customer focus in product decisions.
Strong backend skills in Python (FastAPI preferred) for API design and testing.
Possess good design taste.
Experience deploying/operating with Docker and AWS (ECS/EKS/Lambda, SQS, CloudWatch).
Comfortable with Postgres/MySQL schema design and Redis.
Performance mindset for RSC/Server Actions and DB query optimization.
Experience with production observability tools like Langfuse, OpenTelemetry, Sentry.
Solid security hygiene including PII handling and authentication.

Add these skills to join the top 1% applicants for this job

game-texts

playwright

mysql

aws

jwt

elasticsearch

fastapi

json

redis

docker

websockets

graphql

python

next.js

typescript

stripe

About Sixtyfour

Sixtyfour is a data orchestration engine for company and people data. Our AI agents specialize in enriching detailed datapoints about individuals and organizations, gathering information from both public and proprietary sources. We enable enterprise customers to build custom data pipelines that help them find, enrich, qualify, and act on company-specific requirements for people and business data.

Our Mission

To power how enterprises understand and act on people and companies with world-class intelligence.

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.
Deploy 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.
Maintain a high bar for reliability, performance, and UX; instrument everything.
Be very customer-focused on how certain product decisions impact end customers.

Minimum requirements

------------------------

Strong backend skills in Python (FastAPI preferred): API design, testing, error handling, schema/versioning.
Good design taste is a must.
Experience deploying/operating with Docker and a major cloud (AWS preferred: ECS/EKS/Lambda, SQS, CloudWatch).
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).
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

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