[Hiring] Senior Backend Engineer @Lago

Role Description

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.

• Contribute daily to all parts of our codebase, using our development workflow
• Tackle a wide variety of technical problems throughout the stack
• Help grow the back-end team
• Work with our Product Team and Front-end Engineers to understand customer needs and challenges
• Come up with technical solutions to create and improve our best features and architecture

Qualifications

• Strong knowledge of Ruby (at least 6 years hands-on experience)
• Experience working with large volumes of data and event-driven environments
• A genuine passion for Open-Source: if you've contributed to OSS projects or used OSS tools, let us know!
• A real appetite for the early stages of co-creating a product and shaping Lago's future
• 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)

Requirements

• 6+ years of hands-on experience in software engineering, with strong Ruby expertise
• Experience working with event-driven systems and high-data-volume environments
• Familiarity with background job frameworks (e.g. Sidekiq) and message queues
• Comfort with REST APIs, webhooks, and data integrations
• Strong written and verbal communication skills
• A mindset of ownership, curiosity, and resilience

Benefits

• Work with top-tier talent: Join a team that values excellence, ambition, and accountability
• Shape the future of fintech: Be part of a fast-growing company building the best open-source billing platform
• Remote-friendly: Work from anywhere in Europe (within +2h/-2h of CET), or join us in our Paris office
• Competitive package: Competitive salary and equity for employees based in France
• Make an impact: Your work directly shapes the product used by companies like PayPal, Synthesia, and Mistral.ai