Forward Deployed Engineer

About LagoAt 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 from top-tier investors who believe in our long-term vision. Our platform has attracted 7,000+ stars on GitHub, and forward-thinking companies like Mistral.ai, Together.ai, Groq, and Laravel rely on Lago to power their billing infrastructure.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 experimentation and "failing fast" when needed, we also expect a steep learning curve: make mistakes, but never twice.If you're motivated by technical complexity, leadership impact, and building systems at scale- this is the place for you.About the roleWe’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 stakeholdersRequirements- 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

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 specificationsExperience 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

Tech stack

• Docker
• PostgreSQL
• Ruby on Rails