Senior Backend Engineer — Workflow Engine

About the role

You'll be one of the core engineers on Syntho's workflow execution engine — the product that processes 2 billion tasks per month at sub-50ms P99 latency. This is the heart of everything we do, and you'll help design, build, and scale it.

We're a small, high-trust team where your work has disproportionate impact. You'll work directly with our CTO and have a clear path to Staff or Principal engineer. There's no middle management between you and the architecture decisions.

This role is for someone who loves distributed systems problems, cares deeply about reliability, and wants to build things that thousands of engineering teams depend on every day.

What you'll do

1. Own the core execution engine
   Design and build distributed systems that execute workflows at sub-100ms P99 latency across millions of concurrent runs.
2. Maintain our 99.9% uptime SLA
   We serve thousands of engineering teams who run mission-critical workflows. You'll own incident response, post-mortems, and systemic reliability improvements.
3. Integrate AI into workflow execution
   Work with our AI team to embed LLM-based exception handling, smart retries, and anomaly detection directly into the execution path.
4. Mentor and influence architecture
   Grow junior engineers through code reviews and pair programming. Your architectural opinions will directly shape how we build the next 10x.
5. Drive observability and tooling
   Build the internal tools, dashboards, and alerting systems that keep our team ahead of problems before customers notice them.

What we're looking for

• 5+ years of backend engineering experience, ideally with distributed systems at production scale
• Strong proficiency in Go (our primary language) — Rust or C++ also valued, Python acceptable for scripting
• Deep experience with Kafka, Redis, and PostgreSQL at scale — queues, CDC, schema design
• You've operated services with high availability requirements (99.9%+) and know what that actually means at 3am
• Strong opinions about software, loosely held — you thrive in low-process, high-trust environments with a lot of autonomy
• Bonus: experience with Kubernetes, workflow engines (Temporal, Airflow), or AI/LLM integration at the infrastructure level

The interview process

1. Intro call — 30 minutes
   Casual conversation with the hiring manager. We want to learn about you, your experience, and what you're looking for. No prep needed.
2. Technical screen — async take-home (60 min)
   A real-world systems design problem. No LeetCode, no whiteboard tricks — just the kind of thinking you'd do on the job. Async so you can work when you're sharpest.
3. Virtual onsite — 3 hours with the team
   Three back-to-back sessions: (1) deep systems design, (2) code walkthrough of your take-home, (3) culture / team fit conversation. All over Zoom, all human.
4. Offer — within 48 hours of onsite
   We move fast. Total time from first call to offer is under 2 weeks. We'll give you a full week to decide — no pressure or exploding offers.