Backend Engineer

What you'll be doing

• Scaling our billing system to $100M+ revenue (the hundy) by the end of 2026, and well beyond (the billy?).
• Building billing primitives flexible enough that launching a new pricing model doesn't require rearchitecting everything.
• Making our usage reporting and limiting near-realtime.
• Turning usage and messy raw invoice data into actionable internal reports, accurate forecasts, and compliant financials.
• Making all of the above go brrr.

Example projects

PostHog is generally very open about what we build, but our billing repo understandably isn't. Here's a taste of what we're working on right now though (see our team page for more):

• Implementing a new, ledger-based revenue model and re-building all dashboards and investor reports on top of it.
• Making billing the source of truth for pricing, subscriptions and invoicing.
• Shipping 5+ pricing launches and changes this quarter, including two new pricing models.

You’ll fit right in if

• Strong backend engineer. Python, SQL, and complex data modeling should feel like home.
• Edge cases make you excited, not anxious.
• Experience with data pipelines, task queues, and workflow orchestration - we still have a lot of Celery but are leaning more into Temporal and Dagster.
• If you've done something manually twice (or seen someone else do it) - you're already building an automation or an internal tool to make it easier.
• Happy paths are maybe 10% of billing. You treat error handling, rollbacks, and retries as the actual work - not TODOs you'll "get to later".
• You don't need someone to tell you what to build. You've started a company, led a major project from scratch, or shipped an impressive side project.

Nice to haves

• You've built and scaled usage-based billing systems before (and have the scars to prove it).
• You get weirdly excited about revenue modeling, forecasting and accounting ledgers.
• You have a decent guess which one of these we made up: Q2C / AR / B2R / GAAP / ASC 606 / NRR.

This role is not for you if

• You only want to work with other engineers - billing touches every team at PostHog, from product to finance to GTM to marketing.
• You need clearly defined requirements before you start building.
• You think billing is a solved problem - we thought so too, once.…