Senior Full Stack Engineer

Updated in October 2026 Target start date: March 1, 2027 Compensation: 70,000 to 85,000 EUR yearly gross, depending on profile Location: Either in-office in Paris (Grands Boulevards, 75002) or full remote on Paris timezone     About Upflow   Upflow is the Financial Relationship Management (FRM) platform that helps B2B finance teams collect smarter and get paid by their customers faster, with AI agents working alongside the team. Today, the order-to-cash process is mission critical for businesses, yet it remains fragmented across tools, teams, and workflows. Upflow brings this entire process into one system — four products covering the cycle from invoice to cash (Insights, Collections, Payments, and Cash Application), with AI agents that work alongside the team and a shared intelligence layer underneath. We serve 500+ companies across 30+ countries, including Vercel, Lattice, and Productboard, and are backed by leading investors including Y Combinator, Hedosophia, Hexa, and Lorimer. With teams across the US and Europe, we're building a category-defining company at the intersection of finance, payments, and AI. To learn more about what we do, visit upflow.io . For a behind-the-scenes look at how we work as a team, head to the Inside Upflow section of our blog at upflow.io/blog/inside-upflow About the role You’ll join a small, efficient team who builds high-impact features for our users. You'll work on a wide range of topics, including AI agents, workflow automations, analytics, or payment processing. We invest significantly in AI features, and you'll play a key role in making Upflow the leading agentic software in our field. We work at a fast pace, averaging 20 deploys to production each day, but with high quality standards, and we value pragmatism, ownership, and a growth mindset. AI is also transforming how we work, and we're looking for someone eager to use and optimize agents to help us work more efficiently. You can be based in our Paris office or work remotely. What you will do In your day-to-day, you will: • Architect and implement complex, high-impact product features from start-to-finish. • Collaborate closely with the product manager, the designer, and other engineers to translate business requirements into technical solutions. • Ship clean, maintainable code to production daily. • Participate actively in technical reviews providing and receiving constructive feedback. • Troubleshoot and debug complex product issues. • Optimize application performance and ensure scalability. • Help improve our agentic tools and automations. Our current stack • Frontend: Typescript, React, GraphQL • Backend: Typescript, Node.js, Express, Postgres, and Redis • Infra: GCP, Terraform • Observability: Datadog and Sentry • Github, Copilot, Claude Code, CircleCI Who you are • You have 5+ years of experience in software engineering. • You have strong proficiency in Typescript, React and SQL. • You’re proficient at working with agentic coding assistant such as Claude Code. • You have strong skills in architecture, software reliability, and scalability • You have a product sensibility and care about UX. • You have good teamwork skills and enjoy providing and receiving feedback. • You want to work in a startup environment that values excellence, autonomy, and ownership. • You are fluent in English with strong communication skills. • You are based in Paris, or live in Paris timezone Why join us • International mindset : We have offices in Paris and New York. • On-site or full remote : On-site job in Paris (2-3 days in office), or full remote position on Paris timezone (1 monthly visit in our Paris office). • Exciting moment : Opportunity to contribute to the Engineering function in the AI era. • All-star team : Extrem