Senior Full Stack Engineer

We're hiring a Senior Full Stack Engineer (Backend leaning) at Entropik Labs.

We're looking for someone to lead the backend of a production mobile product with a real time, AI powered backend. Remote, based in Pakistan, full time contract, estimated at 3 months.

What the role actually involves

- You'd own the parts of the system where correctness, latency and cost pull against each other. That starts with the live path: a bidirectional WebSocket service streaming audio and text between mobile clients and a realtime model API, under a hard latency budget. Reconnects, superseded connections, heartbeats, partial turns and provider outages are the job, not edge cases to handle later.

- You'd also own the relational schema and its migrations, Redis as cache, counter, lock and broker, the App Store and Google Play subscription flow with all its webhooks and entitlement states, and the AWS infrastructure the whole thing runs on. Containers, networking, IAM, managed databases, queues, logging, tracing and alerts.

This is a leadership role as well as a hands on one. You'd set architecture and standards, plan and prioritise the work, review code, and be accountable for delivery. At the end of the engagement you'd leave the system documented and hand it over cleanly.

What we're looking for

- Five or more years shipping and operating backend services in production, not just writing them. That means on call, incident response, and debugging the things that only misbehave in production.

- Strong Python and FastAPI, including async endpoints, Pydantic, dependency injection, background tasks and WebSocket endpoints, plus real fluency with asyncio concurrency, cancellation, timeouts and backpressure. 

- Hands on AWS across ECS, EKS, EC2 or Lambda, RDS or Aurora, ElastiCache, SQS and SNS, S3, IAM, VPC and CloudWatch. 

- Deep PostgreSQL: schema design, indexing, query plans, transactions, connection pooling and zero downtime migrations.

- We also need production experience with payments or subscriptions, real time or streaming systems, queues and background jobs, and the deployment side: Docker, CI/CD, secrets management and safe rollouts. And a track record of delivering against fixed scope and deadlines, because three months moves quickly.

Nice to have: infrastructure as code, LLM streaming and evaluation, speech and audio work, Supabase or Firebase, load testing or owning an SLO, and experience on a consumer subscription product.

How to apply:

Send your CV, along with a cover letter and portfolio, to careers@entropiklabs.com.