Senior Frontend React Engineer

NewtonX (600+ clients like TikTok, Microsoft, Salesforce, Bain, Figma and many more) is a research intelligence company helping organizations make better business decisions and train better AI models through verified human intelligence.

We turn specialized human expertise into reliable business decisions (e.g., product launches, marketing strategy, brand reputation tracking, M&A due diligence) and AI training data (frontier model improvements and evals).

We have several million domain experts that we have sourced over the last few years (150+ industries including finance, legal, coding, tax & accounting, healthcare, semiconductors, cybersecurity, STEM and more).

We have worked with AI Labs and Enterprises on topics ranging from sourcing senior electrical and SW engineers for a chip design benchmark to pediatricians and psychiatrists for clinical data to ML engineers and PhD-level statisticians proficient in 3D modeling.

The Role

As part of NewtonX's growing Medellín engineering hub, you'll design and build the fast, reliable, modular user interfaces that power our research platform — sophisticated web applications, reusable component systems, and data-rich experiences built on top of our APIs. You'll work on a small, fast-growing engineering team (under 40 engineers) where individual contributors get in early and help shape the direction of our technology.

This role partners closely with US-based engineering leadership and cross-functional teams. Fluency and confidence in English, written and verbal, is essential — you'll participate in technical reviews, planning, and design discussions with colleagues across time zones.

What You'll Own

Engineering & Delivery

• Design and develop modular, reusable, production-grade UI components and applications.

• Build performant, responsive web interfaces that consume RESTful APIs and handle real-time, data-heavy views.

• Contribute to solution design and participate actively in code review with other engineers.

• Perform debugging, resolve tech debt, and drive continuous code quality improvement.

• Uphold engineering standards across code review, testing, documentation, and CI/CD hygiene.

Technical Contribution & Growth

• Help evaluate and influence the adoption of new technologies, languages, tools, and frameworks.

• Weigh in on architectural decisions with an eye toward scalability and maintainability.

• Pair program and mentor junior engineers as part of a growing local team.

Cross-Functional Collaboration

• Work closely with Product, Design, and US-based Engineering leadership on priorities and platform direction.

• Communicate clearly and proactively across time zones, bridging any gaps between the Medellín and US teams.

• Participate in Agile/Scrum ceremonies and translate business priorities into well-scoped engineering work.

What We're Looking For

Required

• 5 years minimum experience as a software engineer, with strong React experience across multiple projects (tech stack: React, TypeScript, modern frontend tooling).

• Hands-on experience developing web applications that consume REST APIs.

• Experience with client-side state management and asynchronous data handling (e.g., React Query, Redux, or similar).

• Strong command of HTML, CSS, and responsive, cross-browser UI development.

• Comfortable working with modern frontend build and deployment pipelines (e.g., Vite, Webpack, or similar, behind CI/CD).

• Excellent English proficiency — clear, confident communication in writing and in cross-functional meetings with US-based leadership.

• Bachelor's degree or greater.

Nice to Have

• Strong SQL experience with a common relational database; experience tuning PostgreSQL performance.

• Familiarity with cloud infrastructure and horizontally scalable systems (GCP, Kubernetes, Terraform, Cloudflare, or infrastructure-as-code).

• Full Stack Experience (Ideally in Python).

Why Join NewtonX

• Frontier B2B AI: Work on infrastructure powering the most sophisticated research and decision-making workflows in the world.

• High ownership from day one: Get in early on a growing regional team with real influence over technical decisions.

• Exceptional traction: Strong product-market fit with the world's largest investment banks, hedge funds, and consulting firms.

• World-class team: Work alongside smart, driven people who are passionate about their craft.

• Growth opportunity: Join during a hypergrowth phase, with a clear path to greater scope as the Colombia team scales.

What We Offer

• Full Time contract according to Colombian legislation (not a contractor position).

• Competitive compensation and equity aligned to the Medellín market.

• Excellent medical, dental, and vision insurance.

• Generous paid time off, holidays, and parental leave.

• A diverse, collaborative, and positive culture where we invest in and celebrate each other's success.

• Flexible work environment where we work hard but have fun (happy hours, team projects, and global retreats).

NewtonX is proud to be an equal opportunity workplace. We do not discriminate based upon race, religion, color, national origin, sex, sexual orientation, gender identity/expression, age, status as a protected veteran, status as an individual with a disability, or any other applicable legally protected characteristics.