Senior Backend Engineer

<h1><strong>About Lago</strong></h1><p style="min-height:1.5em">At Lago, we're on a mission to make billing simpler, more transparent, and more adaptable for SaaS companies. As the leading open-source billing platform, we empower businesses to build flexible pricing models and scale with confidence. We've raised over <strong>$22 million in funding</strong> from top-tier investors including <strong>Y Combinator</strong> and <strong>FirstMark</strong>, reflecting strong confidence in our vision and growth. Our platform has garnered over <strong>9,000 stars on GitHub</strong>, a testament to our active and growing developer community. Companies such as <strong>PayPal</strong>, <strong>CoreWeave</strong>, <strong>Synthesia</strong> and <a target="_blank" rel="noopener noreferrer nofollow" href="http://Mistral.ai"><strong>Mistral.ai</strong></a> choose Lago for their billing. We're a team of ambitious, focused individuals who work together to solve hard problems with excellence and accountability. At Lago, we value <strong>reliability and proactivity</strong>—we trust each other to own tasks, drive them to completion, and adapt quickly. While we encourage you to <strong>try fast and "fail fast"</strong>, we also expect you to <strong>learn fast</strong>: 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.</p><p style="min-height:1.5em"></p><h1><strong>Overview</strong></h1><p style="min-height:1.5em">We're looking for a Senior Backend Ruby Engineer to contribute to Lago's core product and help scale our open-source billing infrastructure. You'll work across the full backend stack, collaborate closely with Product and Frontend, and help shape how we build and evolve the platform.</p><p style="min-height:1.5em"></p><h1><strong>What You'll Be Doing</strong></h1><ul style="min-height:1.5em"><li><p style="min-height:1.5em">Contribute daily to all parts of our codebase, using our development workflow</p></li><li><p style="min-height:1.5em">Tackle a wide variety of technical problems throughout the stack</p></li><li><p style="min-height:1.5em">Help grow the back-end team</p></li><li><p style="min-height:1.5em">Work with our Product Team and Front-end Engineers to understand customer needs and challenges</p></li><li><p style="min-height:1.5em">Come up with technical solutions to create and improve our best features and architecture</p></li></ul><h1><strong>Who You Are</strong></h1><ul style="min-height:1.5em"><li><p style="min-height:1.5em">Strong knowledge of Ruby (at least 6 years hands-on experience)</p></li><li><p style="min-height:1.5em">Experience working with large volumes of data and event-driven environments</p></li><li><p style="min-height:1.5em">A genuine passion for Open-Source: if you've contributed to OSS projects or used OSS tools, let us know!</p></li><li><p style="min-height:1.5em">A real appetite for the early stages of co-creating a product and shaping Lago's future</p></li><li><p style="min-height:1.5em">Bonus: you've worked on billing or tax projects — whether implementing a billing system, maintaining it, or integrating it with business tools (e.g. a CRM, Finance tools)</p></li></ul><h1><strong>Who You're Not</strong></h1><ul style="min-height:1.5em"><li><p style="min-height:1.5em">You're not looking for a "just ship it" culture without quality standards — we care deeply about both speed and craftsmanship</p></li><li><p style="min-height:1.5em">You're not someone who works in silos — you actively collaborate with Product, Frontend, and your fellow engineers</p></li><li><p style="min-height:1.5em">You're not intimidated by ambiguity — early-stage problems don't always come with a clear spec, and you're comfortable navigating that</p></li><li><p style="min-height:1.5em">You're not allergic to context-switching — in a lean team, priorities shift and you adapt without losing momentum</p></li></ul><h1><strong>Requirements</strong></h1><ul style="min-height:1.5em"><li><p style="min-height:1.5em">6+ years of hands-on experience in software engineering, with strong Ruby expertise</p></li><li><p style="min-height:1.5em">Experience working with event-driven systems and high-data-volume environments</p></li><li><p style="min-height:1.5em">Familiarity with background job frameworks (e.g. Sidekiq) and message queues</p></li><li><p style="min-height:1.5em">Comfort with REST APIs, webhooks, and data integrations</p></li><li><p style="min-height:1.5em">Strong written and verbal communication skills</p></li><li><p style="min-height:1.5em">A mindset of ownership, curiosity, and resilience</p></li></ul><p style="min-height:1.5em"><strong>Nice to have</strong></p><ul style="min-height:1.5em"><li><p style="min-height:1.5em">Experience contributing to or supporting open-source projects</p></li><li><p style="min-height:1.5em">Familiarity with billing systems, fintech, or developer tools</p></li><li><p style="min-height:1.5em">Experience with PostgreSQL, Redis, Kafka, or similar infrastructure</p></li><li><p style="min-height:1.5em">Exposure to containerised environments (Docker, AWS, CI/CD)</p></li></ul><h1><strong>Why Join Lago?</strong></h1><ul style="min-height:1.5em"><li><p style="min-height:1.5em"><strong>Work with top-tier talent</strong>: Join a team that values excellence, ambition, and accountability</p></li><li><p style="min-height:1.5em"><strong>Shape the future of fintech</strong>: Be part of a fast-growing company building the best open-source billing platform</p></li><li><p style="min-height:1.5em"><strong>Remote-friendly</strong>: Work from anywhere in Europe (within +2h/-2h of CET), or join us in our Paris office</p></li><li><p style="min-height:1.5em"><strong>Competitive package</strong>: Competitive salary and equity for employees based in France</p></li><li><p style="min-height:1.5em"><strong>Make an impact</strong>: Your work directly shapes the product used by companies like PayPal, Synthesia, and <a target="_blank" rel="noopener noreferrer nofollow" href="http://Mistral.ai">Mistral.ai</a></p></li></ul><p style="min-height:1.5em">Ready to Build with Us? If you're excited about joining a high-talent team to solve meaningful problems and help businesses thrive, we'd love to hear from you. Apply today and let's build something remarkable—together.</p><p style="min-height:1.5em">Location type: Remote </p><p style="min-height:1.5em">Primary Location: Remote Europe </p><p style="min-height:1.5em">Team: Product Engineering </p><p style="min-height:1.5em">Work Type: Full Time/Permanent Contract </p><p style="min-height:1.5em">Salary: 70,000–100,000 EUR per year</p><p style="min-height:1.5em"><em>(Applicants must be based in the location specified for this role. Applications from other locations will not be considered.)</em></p>