Product Engineer

# **About Lago** At Lago, we're on a mission to make Monetization simpler for tech companies. As the leading open-source billing platform, we help businesses build flexible pricing models and scale with confidence. We've raised over **$22 million in funding** from top-tier investors including **Y Combinator and FirstMark**. Our platform has garnered around **10K stars on GitHub**, a testament to our active and growing developer community. Companies such as **PayPal, CoreWeave, Synthesia, and** [**Mistral.ai**](http://Mistral.ai) choose Lago for their billing. And we have barely spent any money on Marketing or Ads so far. We're a team of ambitious, focused individuals who solve hard problems with excellence and accountability. At Lago, we value **reliability and proactivity**. We trust each other to own tasks, drive them to completion, and continuously improve them. While we encourage you to **try fast and “fail fast”**, we also expect you to **learn fast**: make mistakes, but don't make the same one twice. If you're excited by challenges and want to grow alongside a high-performing, supportive team, this is the place for you. ## **Overview** We're looking for a Senior Product Engineer to help drive Lago's core product forward — someone who obsesses over what gets built and why. You'll work at the intersection of engineering, product and design, owning features end-to-end: from shaping requirements with customers to shipping and iterating in production. This is a high-ownership role for someone who doesn't want to wait for a spec — they want to write it, then build it. **What you'll be doing** - Own product features end-to-end, from discovery and scoping to implementation, release, and iteration in production. - Work directly with customers and internal teams to understand pain points, clarify requirements, and identify the highest-impact problems to solve. - Contribute actively to product decisions, not just technical execution. - Build clean, reliable, and maintainable solutions with a strong sense of quality, usability, and customer impact. - Collaborate closely with engineering, product, design, and GTM teams to align on priorities and deliver high-quality outcomes. - Use AI thoughtfully to move faster, explore solutions, prototype ideas, and improve your own engineering workflow. - Engage with our developer community by contributing to the open-source repository, responding to GitHub issues, and representing Lago's engineering standards publicly. **Who you are** - You're comfortable working in ambiguous, fast-moving environments. You create clarity instead of waiting for it. - You care about what gets built and why, not only how it gets implemented. - You have strong product instincts and naturally think about user experience, business impact, customer needs, and technical trade-offs. - You communicate clearly in writing and in conversation. You know how to align people in a room, challenge assumptions constructively, and question your own assumptions when needed. - You know how to build with and without AI. You can use AI tools to move faster, but you also understand the fundamentals deeply enough to reason, debug, and make decisions independently. - You value ownership. When you take on a problem, you drive it to completion. - You're pragmatic. You know when to move fast, when to go deep, and when to keep things simple. **Requirements** - 5+ years of software engineering or product engineering experience, with a track record of shipping products users love — not just systems that work. - Strong product and design instincts: you think about UX, business impact, customer needs, and technical correctness together. - Experience building B2B SaaS products, ideally developer tools, APIs, infrastructure, billing, fintech, or usage-based platforms. - Strong AI skills: you know how to use AI tools effectively to build, prototype, debug, and accelerate your work — while still being able to build and reason without relying on them…