Senior Software Developer

Join to apply for the Senior Software Developer role at Zeffy Get AI-powered advice on this job and more exclusive features. This range is provided by Zeffy. Your actual pay will be based on your skills and experience — talk with your recruiter to learn more. About Zeffy 🌍 Over 10% of the North American workforce is dedicated to nonprofit causes - that's 15 million people dedicated to impacting the world positively. By making them all more effective and impactful, we've found a powerful leverage point for change. That's the scale we're building toward. ⚡ This isn't just vision - it's working. We've helped 50,000+ nonprofits raise over $1.5 billion with zero fees, saving them $60M+ for their causes and countless hours thanks to efficient technology. With 150% year-over-year growth and 2+ years of profitability, we're proving that sustainable business success and social impact go hand in hand. 🚀 Our recipe? A small team of ambitious, smart, and kind people who work exceptionally well together. We believe this is the most effective way to go fast and far - growing quickly while maintaining our efficiency and values. 🌱 Zeffy is a B-Corp company. About The Role As a Senior Software Developer at Zeffy, you’ll play a key role in building and scaling the best tech for charities. Over The Past Two Months, Our Team Has Enabled Tap to Pay on iOS to make in-person donations frictionless. Built a performance dashboard so organizations can track campaign results in real time. Created a feature to send real postcards to donors as thank-you notes. Launched an AI assistant to help nonprofits write better donor communications. Migrated our backend from GraphQL to tRPC to improve performance and simplify development. You’ll take ownership on similar projects, things that go from idea to production quickly and actually matter to the people using them. You’ll make judgment calls, simplify and help teammates do the same. As a senior developer, you’ll also help shape our processes and mentor others to maintain Zeffy’s “simple and fast” culture as we grow. Development Principles At Zeffy We always optimize the ratio impact / effort, it’s what we call Zeffy perfectionism, perfection in impact. We build the simplest solution first to validate ideas quickly, keeping the codebase clean without solving problems that don’t exist yet. We are organized in 2 months cycle, to make sure we prioritize radically. We set ourselves targets on the 4 following dimensions: efficiency, security, stability and performance. Trust and ownership: every target is clear and owned by one person who has full autonomy to reach it. Owned by one person doesn’t mean working alone on it. Continuous improvement: We regularly review and refine our processes, promoting a culture of learning and growth through feedback. Our Stack Frontend: React/Next.js (Typescript) Backend: Nest.js (TypeScript) Database: PostgreSQL, Algolia CI/CD: GitHub Actions, Cypress Previous experience in these technologies is not required, we’ll help you ramp up quickly through focused onboarding and internal bootcamps. Preferred Experience (qualifications) We’re looking for someone with at least 4 years of experience as developer, ideally in SaaS or web-based products. We move fast by keeping things simple, and we want someone who shares that mindset: experienced enough to know when to push for structure, and wise enough to know when to cut the noise and just build. you’ve built real products, learned from trial and error, and developed the instinct to separate what truly matters from what doesn’t. you bring seniority through judgment, not hierarchy — through the ability to make smart, pragmatic decisions that balance quality and speed. you value clarity over complexity, progress over perfection. You mentor others with empathy, share what you’ve learned, and help elevate the team without slowing it down. If you’re fed up with unnecessary complexity — endless processes, over-engineered solutions, or meetings that don’t move the work forward — you’ll feel at home here. 💡 Research shows that candidates from underrepresented backgrounds often don't apply for roles if they don't check every box. If this applies to you and you are interested in the position, we'd love to hear from you What’s in it for you 🏖️ 5 weeks holiday + RTT per calendar year 💰 Competitive stock option program 🏥 Health insurance (with Alan) 🚲 Allowance for ecological transport #bike #transit 🤝 Team volunteering four times per year 🏢 Offices located in the heart of Paris 11ème, with the possibility of flexible, hybrid work 🌍 Offsite summit once a year with the entire team ✨ Work with individuals driven to make a profound and positive impact on the world Recruitment Process Call with Recruiter (45 min) Meeting with Hiring Manager (1.5h) Case Study (2h) Cultural interview with leadership (1h) Team lunch & Reference check Job offer Seniority level Mid-Senior level Employment type Full-time Job function Engineering and Information Technology Industries Software Development Referrals increase your chances of interviewing at Zeffy by 2x #J-18808-Ljbffr