Senior Full Stack JS Engineer

NineTwoThree AI Studio; España; On-site; PHP 9,404,000 - 11,912,000; Full time

Benefits offered by this job

Vacation & Well-being Budget

Health Insurance allowance

Maternity/Paternity leave

Professional development support

Hardware on business needs

Job summary

NineTwoThree AI Studio in a remote‑first setup seeks a true senior full‑stack engineer who leads projects, mentors engineers, and ensures execution quality. You’ll shape technical strategy, align with product vision, and deliver scalable AI‑powered web and mobile apps.

Requirements include 5+ years in full‑stack development (React, Node.js, JavaScript/TypeScript), strong cloud experience, design pattern knowledge, and excellent communication with clients and teams.

Qualifications

• 5+ years of experience in Full Stack Software Development with React/Node.js.
• Strong knowledge of cloud platforms and design patterns.
• Excellent communication with clients and teams.

Responsibilities

• Lead projects end-to-end and guide teams to execution quality.
• Align product vision, technical feasibility, and business needs.
• Architect scalable AI-powered web and mobile applications.
• Mentor engineers and ensure coding standards.
• Translate business needs into technical decisions with timelines.

Skills

Full Stack Development

React

Node.js

JavaScript

TypeScript

SQL

Cloud Platforms

AWS

Azure

GCP

Design Patterns

Communication

English Proficiency

Tools

Microservices

REST APIs

OAuth/SAML

Job description

Why Join Us

100% remote | Global team | Full-time

If you're looking to work on cutting-edge AI products, solve challenging problems, and be part of a fast-moving, high-talent team, you'll love it here.

Join NineTwoThree AI Studio, a remote-first product design, engineering, and marketing studio, founded in 2012 and based in Boston. We build AI-powered web and mobile apps for big brands and fast-moving startups.

You’ll work with really smart people—the kind of teammates who challenge you, push you forward, and make you better. We move fast and focus on getting things done.

We’ve been growing 20% every year for the last 5 years, which means there’s plenty of room for career growth and promotions. Our work speaks for itself—some of our customers found us through five layers of referrals. That’s how much people appreciate what we do.

We run on clear processes and strong leadership, so while we move quickly, we don’t do chaos. We do high-quality work, and we do it right.

We focus on products with a positive impact in various domains from sports and health, to logistics and nuclear. But if you’re into gambling, adult entertainment, or crypto, we’re not your place.

What You’ll Do

Lead, not just code — Seniors at NineTwoThree don’t just write great code—they lead projects, guide teams, and ensure execution quality:

• Connect the dots between product vision, technical feasibility, and business needs
• Communicate options, trade-offs, costs, and timelines clearly to both our team and client
• Lead projects end-to-end — from technical strategy to execution
• Architect solutions and apply best practices for scalable, AI-powered products
• Guide and mentor engineers, ensuring quality while delivering fast
• Translate business needs into technical decisions, explaining trade-offs and timelines
• Solve hard problems, direct implementation, and coordinate technical challenges with clients

Who We’re Looking For

True senior engineers — not just people with years of experience, but those who own solutions and drive execution.

• 5+ years of experience in Full Stack Software Development (React, Node.js, JavaScript, TypeScript, SQL)
• Strong knowledge of cloud platforms (AWS, Azure or GCP)
• Clear and thorough understanding of design patterns and software development best practices
• Great communicators who can explain options, trade-offs, and technical details to clients and teams
• Ability to break down complex problems into manageable tasks;
• Passion maintaining code style and standards and holding people accountable;
• Hands-on experience with microservices architecture;
• Experience with React.js, Node.js, JavaScript and Typescript (at least 5 years);
• RESTful API design and implementation;
• OAuth and single sign-on (SAML);
• Leaders who ensure execution quality, push teams forward, and keep projects on track
• Strong communication and analytical skills
• Relational and no-SQL databases — MySQL, PostgreSQL, Redis etc;
• Solid understanding of principles of JavaScript/TypeScript languages
• Ability to freely express/present/discuss ideas in English (B2-C1 level)
• Flexibility with working hours to participate in meetings with Eastern USA

Not for you

If you’re looking for a pure coding role where someone else makes the decisions, this isn’t it.

Benefits

What We Offer

• Annual paid vacation: 20 days-off per year during the first 3 years, further increasing to 25 days in later years
• Paid sick leave, 10 national holidays and 2 company days-off
• Well-being budget
• Health Insurance allowance
• Maternity/paternity leave
• Accounting assistance
• Reimbursement of expenses for professional development courses/certifications (up to 100% in agreement with the Manager)
• Hardware upon business needs
• Strong positive engineering culture, a tightly-knit team of professionals with a good sense of humor

What’s The Process

We make the process fast and responsive. Short HR interview, Technical Q&A, Hands-on Practical Session (no bubble sorts), CTO interview (sometimes), Offer.