Forward deployed Engineer - Paris, France at Lago (S21) €65K - €85K EUR Open Source Metering and Usage Based Billing Paris, IDF, FR / Paris, Île-de-France, FR Full-time US citizenship/visa not required 3+ years About Lago 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 $22 million in funding from top-tier investors, reflecting strong confidence in our vision and growth. Our platform has garnered over 8,000 stars on GitHub, a testament to our active and growing developer community. Next-gen companies such as Mistral.ai, Groq, and Laravel chose 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 reliability and proactivity—we trust each other to own tasks, drive them to completion, and adapt quickly. 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. About the role The Role We’re hiring a Forward Deployed Engineer to join our Product team. This role is ideal for engineers who enjoy solving real-world customer challenges hands-on. You’ll work directly with users to support their implementation of Lago, guide them through architectural and product decisions, and build or adapt code that helps them succeed. You’ll act as a bridge between the user and Lago’s internal teams — writing production-level code, improving onboarding assets, supporting complex integrations, and channeling user feedback directly into our product development cycle. Responsibilities Lead technical implementation efforts for strategic users — from initial architecture reviews to production deployment Write scripts, integration templates, and lightweight services to support custom use cases Contribute to Lago’s open-source SDKs, example repositories, and public documentation Collaborate with users’ engineering teams to resolve complex integration challenges Identify edge cases and implementation patterns, and feed them into product discussions Build internal tooling and utilities that support faster and more robust deployments Act as a hands-on technical advisor to both internal and external stakeholders Requirements 3+ years of experience as a Software Engineer or in a technical role working with external users Strong backend skills, especially in Ruby on Rails Comfortable with PostgreSQL, Docker, Sidekiq, Clickhouse and event-based or asynchronous processing Familiarity with RESTful APIs, webhooks, authentication flows, and OpenAPI specifications Experience working with background jobs, queuing systems, and production environments Excellent debugging and communication skills Based in or willing to relocate to Paris, with in-office presence at least 3 days a week Bonus: experience in billing infrastructure, SaaS metering, or open-source development Why Join Lago? Work on a product loved by engineers and product teams Join a lean and ambitious team building foundational infrastructure Contribute to an open-source project with real-world impact Competitive compensation and early equity in a fast-growing company 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. Technology Back-end: Ruby, Postgres, AWS Front-end: .js, React, GraphQL, Typescript