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Posted Jul 26, 2025

SDK Engineer - Feature Flags

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Help us to increase the number of successful products in the world!

About PostHog

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

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

Who we’re looking for

We're looking for a pragmatic polyglot engineer passionate about crafting high-quality developer experiences across a range of languages and platforms. You're someone who thrives on improving SDKs that developers enjoy using — ones that are fast, reliable, and feel native no matter the tech stack.

In this role, you'll focus on our feature flag SDKs, used in server-side apps and infrastructure to power flag evaluation. Some of these SDKs make remote requests to our evaluation engine, while others run locally, meaning correctness and performance are equally critical. Many other PostHog products depend on the SDKs, so you'll be working on critical infrastructure that touches many parts of the company.

You should be deeply familiar with at least one of our primary languages/platforms (Python, Go, Rust, C#, or TypeScript), and confident picking up enough of the others to make meaningful contributions across the SDK ecosystem. You’ll work closely with backend, infra, and product teams to ensure our SDKs remain robust and delightful, while also helping us find ways to support more languages more efficiently.

What makes this role unique

What you'll be doing

You’ll maintain and extend PostHog’s feature flag SDKs, ensuring they are performant, idiomatic, and correct across a wide range of customer use cases. You’ll contribute to both local evaluation logic and remote integration paths, often working closely with the team that owns our flag evaluation service (written in Rust). You’ll also collaborate with language experts across PostHog to ensure high standards in SDK ergonomics and platform conventions.

A typical week might involve:
- Debugging a subtle evaluation bug in the posthog-go SDK- Prototyping a cross-platform testing framework for SDK correctness- Implementing local evaluation in a new language SDK- Reviewing a community contribution to the posthog-node SDK

Requirements

Nice to have


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!

Benefits

What we offer in return:

Originally posted on Himalayas

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