Backend Engineer - Feature Flags

We're seeking a high-performance API engineer who thrives on the challenge of building systems that need to respond in single-digit milliseconds at scale. You're the type of engineer who gets excited about shaving microseconds off response times and designing elegant, efficient systems that can handle millions of requests per minute without breaking a sweat. The ideal candidate has experience with high-throughput, low-latency services similar to: Real-time bidding platforms Payment processing systems Recommendation engines Authentication services Content delivery networks You're not just a performance optimizer - you care deeply about clean architecture, observability, and creating APIs that developers love to use. You understand that in the feature flags world, your code is in the critical path of every customer's user experience, and you take that responsibility seriously. Unlike many high-scale API engineering roles where you're maintaining a small part of a massive system, at PostHog you'll: Own the entire service from end-to-end: Design, build, deploy, and scale the complete feature flags evaluation engine. Build in the hot path with real impact: Your code runs in the critical path of our customers' applications, making a direct impact on their user experience. Start from first principles: Scale up new services from the ground up rather than just maintaining existing infrastructure. Set your own performance targets: You won't be constrained by other teams' requirements - you'll define and own the latency goals that make our customers successful. See immediate results: Deploy optimizations and see the impact on performance metrics in real-time. Work with cutting-edge tech: Our evaluation engine is written in Rust for maximum performance, while our application layer uses Python/Django.

We're equipping every developer to build successful products by giving them a suite of products to analyze, test, observe, and deploy new features. We currently offer product and web analytics, session replay, feature flags, experiments, a CDP, SQL access, a data warehouse, and LLM observability… and there's plenty more to come. PostHog was created as an open-source project during Y Combinator's W20 cohort. We had the most successful B2B software launch on HackerNews since 2012 with a product that was just 4 weeks old. Since then, more than 100,000 companies have installed the platform. We've had huge success with our paid upgrades, raised bags of money from some of the world's top investors, and have extremely strong product-led growth – 97% driven by word of mouth. We're growing quickly, but sustainably. We're also default alive, averaging 10% monthly revenue growth and with more than $20m ARR. We're staying focused on building an awesome product for end users, hiring a handful of exceptional team members, and seeing fantastic growth as a result.