Backend Engineer

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.

What we value

• We are open source - building a huge community around a free-for-life product is key to PostHog's strategy.

• We aim to become the most transparent company, ever. In order to enable teams to make great decisions, we share as much information as we can. In our public handbook everyone can read about our roadmap, how we pay (or even let go of) people, what our strategy is, and who we have raised money from. We also have regular team-wide feedback sessions, where we share honest feedback with each other.

• Working autonomously and maximizing impact - we don’t tell anyone what to do. Everyone chooses what to work on next based on what is going to have the biggest impact on our customers.

Solve big problems - we haven't built our defining feature yet. We are all about acting fast, innovating, and iterating.

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.

Our team is based in Seattle, but we embrace remote work and are open to candidates in PST through CET time zones. You'll collaborate with a distributed team that's passionate about building world-class developer tools.

We're growing very quickly at PostHog, and our Feature Flags service is scaling rapidly. You'll be responsible for building and maintaining our feature flags evaluation engine that makes complex decisions based on person/group properties at high speed and scale.

We recently rewrote the service in Rust and are working on adding new targeting features and continuing to improve the latency. You'll be working on a critical part of our infrastructure that customers rely on for real-time feature delivery. One day, you'll be making high-level architecture decisions, the next you'll be optimizing a performance bottleneck that slashes latency by 50%, and the day after you'll work directly with customers to implement complex targeting rules that meet their specific needs.

• Experience with any systems programming language and/or backend web frameworks. We use Python and Rust a lot–our app is written in Django, and the flags evaluation API is written in Rust–so experience in those languages is a plus, but not required

• You have experience building systems that handle high volumes of requests/data (millions+ per minute)

• You can choose a sensible architecture quickly, and then ship it faster than other people think is possible

• Strong understanding of performance optimization techniques, caching strategies, and distributed systems principles

Nice to have

• Experience with feature flag systems or similar real-time decision engines

• You've carried a pager and have dealt with incidents

• You're comfortable with provisioning and deploying infrastructure

• Experience with benchmarking and profiling tools

• Knowledge of observability systems and practices

We believe people from diverse backgrounds, with different identities and experiences, make our product and our company better. That’s why we dedicated a page in our handbook to diversity and inclusion. No matter your background, we'd love to hear from you! Alignment with our values is just as important as experience! 🙏

Also, if you have a disability, please let us know if there's any way we can make the interview process better for you - we're happy to accommodate!