Backend Engineer - Europe/UK Timezone

ABOUT POSTHOG Product development used to mean manually writing code, running analysis, diagnosing bugs, and rolling out changes using dozens of tools. PostHog is the only platform that acts like a co-pilot for you (and your AI agents) to do it all – autonomously. We started with open-source product analytics, launched out of Y Combinator's W20 cohort https://posthog.com/handbook/story. We've since shipped more than a dozen products https://posthog.com/products, including: - PostHog Code https://posthog.com/code, the only AI devtool that understands your product, not just your codebase. - A built-in data warehouse https://posthog.com/docs/data-warehouse, so users can query product and customer data together using custom SQL insights. - PostHog AI https://posthog.com/ai, an AI-powered analyst that answers product questions, helps users find useful session recordings, and writes custom SQL queries. We are: 1. Product-led. More than 450,000 organizations have installed PostHog, mostly driven by word-of-mouth. We have intensely strong product-market fit. 2. Default alive https://paulgraham.com/aord.html. Revenue is growing incredibly quickly, and we're very efficient. We raise money to push ambition and grow faster, not to keep the lights on. 3. Well-funded. We've raised more than $180m from some of the world's top investors. We're set up for a long, ambitious journey. We're focused on building an awesome product for end users, hiring exceptional teammates, shipping fast, and being as weird as possible https://posthog.com/deskhog. THINGS WE CARE ABOUT - Transparency: Everyone can read about our roadmap, how we pay (or even let go of) people, our strategy, and how we work, in our public company handbook https://posthog.com/handbook. Internally, we share revenue, notes and slides from board meetings, and fundraising plans, so everyone has the context they need to make good decisions. - Autonomy: We don’t tell anyone what to do. Everyone chooses what to work on next based on what's going to have the biggest impact on our customers, and what they find interesting and motivating to work on. Engineers lead product teams https://posthog.com/handbook/wide-company and make product decisions https://posthog.com/handbook/which-products. Teams are flexible and easy to change when needed. - Shipping fast: Why not now? https://posthog.com/handbook/values#why-not-now We want to build a lot of products; we can't do that shipping at a normal pace. We've built the company around small teams – autonomous, highly-efficient groups of cracked engineers https://posthog.com/founders/cracked-manifesto who can outship much larger companies because they own their products end-to-end. - Time for building: Nothing gets shipped in a meeting. We're a natively remote company. We default to async communication – PRs > Issues > Slack. Tuesdays and Thursdays are meeting-free days https://posthog.com/handbook/company/culture#were-on-the-makers-schedule, and we prioritize heads down building time over perfect coordination. This will be the most productive job you've ever had. - Ambition: We want to solve big problems. We strongly believe that aiming for the best possible upside, and sometimes missing, is better than never trying. We're optimistic about what's possible and our ability to get there. - Being weird: Weird means redesigning an already world-class website for the 5th time. It means shipping literally every product that relates to customer data. It means building an objectively unnecessary developer toy https://posthog.com/deskhog with dubious shareholder value. Doing weird stuff is a competitive advantage. And it's fun. WHO WE'RE LOOKING FOR We're looking for a backend engineer excited about systems that answer in single-digit milliseconds, millions of times a minute, without breaking a sweat. Our feature flags evaluation service sits in the critical path of every customer's app. When it's slow, their product is slow. When it's down, they can't ship. That responsibility should motivate you, not terrify you. You've built high-throughput, low-latency services where correctness and tail latency both matter: real-time bidding, payment processing, recommendation engines, auth services, or CDNs. We write Rust and Python, plus a pile of client SDK languages (JS/TS, Go, Ruby, PHP, Java, .NET, iOS, Android, Flutter, and more). You don't need all of them, but you should be a polyglot (or happy to become one) who cares about developer experience as much as performance. Flags should be trivial to add, obvious to manage, and impossible to forget about. WHAT YOU'LL BE DOING Our team is distributed. For this role we're hiring in European time zones to balance the team. You'll overlap with teammates daily, but much of your day is solo. You need to own your work without someone setting the agenda. We build the feature flag tools, SDKs, evaluation services, and in-app UI that customers use to safely ship features and make data-driven decisions. We own the reliability, stability, and performance of the targeting service and local evaluation endpoints, end to end. You won't maintain a small corner of a massive system. You'll own whole services and set their latency and uptime targets yourself. Some of what we’re working on: - Real-time cohorts, our most-requested feature. Membership is computed on a delay today, which makes it useless for targeting like "users who did X in the last five minutes." Evaluating it in real time at flag-check time collapses a whole category of custom targeting logic people build themselves. - Moving from a read-heavy to a write-heavy architecture, including a dedicated store for flag evaluation so we're not coupled to the shared Persons DB. - An AI-first flag management tool we're dogfooding internally, so agents can create, modify, and reason about flags without ever opening the UI. - Reliability and performance work to lower our p50/p90/p99 latencies and isolate the evaluation path from upstream failures (load shedding, request hedging, decoupling from the Persons DB). One day you're making an architecture call, the next you're cutting p99 latency in half, the day after you're porting cache building to Rust. REQUIREMENTS - You've built and operated systems that handle high volumes of requests or data (millions+ per minute), and you care about tail latency, caching, and distributed systems failure modes - You're productive in Rust and Python, or confident you'll get there fast. While the app is Django, the evaluation engine and much of our backend infrastructure is in Rust or moving to it. - You work independently. You can pick a sensible architecture, ship it faster than people expect, and drive it to done without being managed - You ship changes quickly without breaking a service customers depend on to launch - You're based in a European time zone NICE TO HAVE - Experience with feature flags, customer data platforms, or other real-time decision engines - You've carried a pager and dealt with incidents - You're comfortable provisioning and maintaining cloud infrastructure - Experience with benchmarking and profiling tools If this sounds like you, we should talk. We are committed to ensuring a fair and accessible interview process. If you need any accommodations or adjustments, please let us know. #LI-DNI