Quick summary: We're looking for a design engineer who's obsessed with craft. You'll build the interface where non-technical users manage their AI employees - it needs to be fast, clear, beautiful, and bulletproof. The challenge: creating React components that are performant (understanding rendering cycles, minimizing backend calls) and delightful (smooth interactions, thoughtful details). You care about milliseconds and pixels equally.
Why join Sintra?
We build AI employees for small businesses. Real helpers with personalities, not faceless chatbots. They handle the work that keeps owners up at night - answering customer emails, posting on social media, analyzing sales data. For business owners who've always worked alone, we're giving them their first team.
50,000+ businesses use Sintra because for the first time someone made AI actually useful for them. While Silicon Valley builds for tech companies, we're building for the florist who needs help with Instagram, the contractor drowning in invoices, the restaurant owner who can't keep up with reviews.
This is a unique moment in history. AI just became good enough to fundamentally change how small businesses operate. Behind every business is someone trying hard for their family. Someone with one goal - put food on the table. And our job is to help them succeed.
Having just raised our $17M seed round, we're off to the races. Small, fast-moving team building together in person. We ship daily, take ownership of what we build, and live by one principle - work is play.
Who we're looking for
- 4+ years building production React applications with TypeScript
- Deep understanding of rendering optimization, state management, and performance profiling
- Obsessed with UI details - spacing, timing, interactions that feel right
- Experience building reusable component systems
- Track record of making things faster and fixing what's broken
- Comfortable using AI tools to ship faster without sacrificing quality
What you'll do
- Build user interface for business owners to interact with their AI employees
- Optimize performance based on data - measure render times, track interaction metrics, profile bottlenecks
- Create reusable component systems that scale across the product
- Implement smooth interactions and micro-animations that make AI feel alive
- Fix the broken things that annoy users - that loading state, that janky scroll, that confusing flow
- Instrument everything - add tracking to measure real user behavior and iterate based on data
- Collaborate with designers to keep things simple for non-technical users
- Maintain clean React patterns that make the codebase easy to navigate for both AI and developers
Our tech stack
- Frontend: React
- Backend: Python with FastAPI (core), Node (microservices)
- Infrastructure: Railway, AWS, multiple LLM providers
- DevOps & Tooling: Github Actions, Grafana
Our hiring process
- Fill in the application form. If we see a fit, we'll reach out for an intro call.
- Complete a take-home task that mirrors real work you'd do here. Be prepared to explain what you did and why.
- Join us for a trial day in Vilnius. Meet the team, see if we're right for each other.
- Get an offer if it's a mutual fit.
We understand good people have options, that's why we move super fast. Life's too short for drawn-out hiring processes.
What we offer
- Compensation & Equity
Top-of-market salary in Vilnius plus meaningful equity, so you own part of what you build.
Salary range for this role: €5,000-8,000/month depending on expertise and experience. - Health & Wellness
Health insurance, gym membership with personal trainer option, team lunch at the office. - Seamless Relocation
Relocation bonus and support to make your move to Vilnius smooth.
We’re looking for a Frontend Engineer to join our devepment team and help shape experiences that are not just functional — but emotional, beautiful, and a joy to use. You’ll work closely with product and design to build thoughtful interfaces that resonate with users.
- Owning and evolving the web frontend stack using React.js (additionally Next.js).
- Build and improve new product features — starting with ankle reduction and activation flows in our existing app.
- Implement microinteractions, transitions, and emotion-driven UI that make the experience feel effortless and alive.
- Work closely with product and design — not just to build what's planned, but to help shape how it should feel.
- Collaborate with mobile and backend engineers to ensure smooth cross-platform experience.
- At least 4 years experience building frontends using JavaScript/TypeScript and React.
- You've shipped at least one complete product or feature — ideally something you can show.
- You have a strong visual eye and care for emotional design — not just pixels, but how the interface makes people feel.
- Experience with micro-interactions, animation, ergonomics, and small-but-mighty UI details.
- You’re self-driven and don’t need hand-holding — we want someone who can own their space.
- Bonus: experience with Next.js and design systems
- Salary ranges from €5,000 to €8,000 depending on expertise and experience
- Work when and where you’re most productive — remote, hybrid, or in-office
- Team lunch every day, cooked with love by our in-house chefs
- Stock options after your trial period
- Gym access + personal trainer (optional but encouraged — it’s fun with the team!)
- Spontaneous team trips — we recently flew the team to San Francisco
- MacBook and any other tools you need to do your best work