Junior Fullstack Software Engineer

Prex Technologies is hiring a Junior Fullstack Software Engineer to join the product team of one of our US partner companies: a fast-growing, venture-backed AI startup with a live product and paying customers.
This is not a back-office support role. You'll be part of a small, high-caliber team working directly with the founders, shipping features that real customers use the same week. You'll work across the whole stack and use AI tools like Claude every day as part of how the team builds.
Two things matter more than anything else in this role: communication and agency.
Communication, because you'll be working remotely with a US team and US customers. The engineers who thrive here keep people in the loop without being asked, flag problems early instead of hiding them, explain their decisions clearly, and ask good questions when something isn't clear.
Agency, because in a small startup nobody hands you a perfectly defined ticket. We're looking for someone who sees a problem and owns it: figures out what needs to happen, proposes a solution, and drives it to done without waiting for permission or constant direction.
Technical skills can be taught quickly. Communication and ownership are what make someone succeed here, which is why they count more than years on your résumé.
You'll be contracted through Prex, work 100% remotely from Latin America, paid in USD, with hours aligned to US Eastern time.
Responsibilities
Own features end-to-end, from understanding the problem to shipping it to production, across web and mobile apps built with React, React Native, Ruby on Rails, Python and Node.js.
Communicate proactively with the founders and the team: share progress, surface blockers early and explain trade-offs clearly.
Work directly with customers to understand their problems and turn them into simple, effective product experiences.
Identify problems and opportunities on your own, propose solutions and drive them to completion without waiting to be told.
Write clean, maintainable, well-tested code, using AI tools as part of your daily workflow.
Take part in code reviews, giving and receiving honest feedback.
Help scale the platform as it grows, including backend services, databases and cloud infrastructure.
Requirements
Excellent communication skills, written and spoken, in English: you'll work daily with a US team and US customers, and clear, proactive communication is non-negotiable.
High agency: a track record of taking ownership, whether at a job, in university or in your own projects, and getting things done without close supervision.
Solid fullstack foundation: TypeScript/React plus at least one of Ruby on Rails, Python or Node.js. Python is a strong plus.
Experience with relational databases (PostgreSQL, MySQL or similar) and RESTful APIs.
Comfortable with Git and collaborative development workflows.
Familiarity with a cloud platform (GCP, AWS or Azure) is a plus.
Growth mindset, curiosity and a builder's attitude.
Professional experience is welcome but not required: recent graduates with strong personal or academic projects (show us your GitHub) are encouraged to apply.

Work arrangement
Yes