Quick summary: We're looking for a full-stack engineer for our Activations team - a small, high-impact unit focused on day 2-7 retention. You'll implement fast experiments across the entire user journey. Must be strong in React/Python, comfortable jumping into any part of our codebase, and able to ship clean code at high velocity.
This role is for engineers who are hungry, obsessed with moving metrics, and want to see their code directly impact 50,000+ businesses.
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 shipping production React/Python applications
- Experience with growth engineering - A/B tests, funnel optimization, retention metrics
- Comfortable with LLM APIs, prompt engineering, and AI tool development
- Can navigate large codebases and ship changes same day
- Track record of identifying bottlenecks and fixing them through focused iteration
- Excited about AI/LLMs and staying on the cutting edge
- Comfortable using AI tools to accelerate development
- Works independently - takes problems to production without hand-holding
What you'll do
- Own entire activation flows end-to-end - prioritize problems, architect solutions, ship them
- Build creative activation experiments that help users understand what AI employees can do for their business
- Customize day 1-7 experiences - different flows for different business types, feature flags to test what works
- Make the first AI conversation perfect - better prompts, smarter tool selection, clear success moments
- Eliminate errors in early user sessions through bulletproof error handling and fallbacks
- Design systems to capture business context, then ensure AI actually uses it
- Track everything - every click, AI interaction, and drop-off point
- Build viral loops into the product - team invites, sharing
- Ship product guidance that adapts based on what users actually do
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 that you own a 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.