Senior Front-End Engineer - Freelance

Who we are: 

We are Boombit, a full-service agency and content studio that empowers companies to grow through strategy, creativity, technology services, and exceptional human talent. Since 2012, we have propelled companies forward by delivering quality, innovation, and purpose-driven work.

Job purpose:

As a Senior Front-End Engineer, you will take ownership of technical execution within a specific track or feature set. You can operate as a technical leader, guiding and mentoring junior developers, or as a deep individual contributor, driving excellence in implementation, architecture, and performance.

At this level, you’re expected to begin shaping your trajectory towards solution architecture, technical leadership, or a specialized front-end domain such as performance optimization, accessibility, or design systems.

Job details: 

• Location: 100% remote - open to Colombia based candidates.
• Schedule: Monday to Friday, 8:00 AM - 5:00 PM Costa Rica time zone.
• Work Model: Full-time flexible (freelance based on hours worked / on-demand engagement)
• Language Proficiency: Spanish (Native) / English (C1+ written, spoken, and reading)
• Availability: Immediate availability preferred

Key Responsibilities:

UI Implementation & Code Quality

• Design and implement advanced UI features using React.js and modern JavaScript/TypeScript best practices.
• Translate high-fidelity designs into semantic, accessible, and cross-browser-compatible HTML/CSS.
• Apply and enforce coding standards using linting tools, static analysis, and structured code reviews.
• Maintain high code quality through modular architecture, reusable components, and clear documentation.

Testing & Debugging

• Define testing strategies and implement unit, integration, and end-to-end tests using Jest, Testing Library, and Cypress.
• Lead debugging and root cause analysis for production issues, performance, and visual inconsistencies.
• Use profiling tools to identify inefficiencies and optimize render paths, state handling, and interaction flows.

Performance Optimization & Responsiveness

• Optimize web performance across the stack: code splitting, lazy loading, render minimization, and bundle size reduction.
• Implement mobile-first responsive interfaces, ensuring smooth experiences across devices and browsers.
• Monitor and improve performance metrics (e.g., Core Web Vitals) and user experience KPIs.

DevOps & Integration

• Integrate front-end builds into CI/CD pipelines, collaborating with DevOps and platform engineers.
• Manage environment configurations, feature flags, and deployment workflows across development, staging, and production.
• Collaborate on observability and logging, using tools such as Sentry, New Relic, and monitoring dashboards.

Team Collaboration & Process Improvement

• Collaborate cross-functionally with Design, Product, and Backend teams to ensure feasibility, performance, and UX alignment.
• Represent the front-end discipline in planning sessions and cross-functional meetings, articulating technical considerations and risks.
• Identify opportunities to improve tooling, workflows, or architecture, and propose enhancements aligned with team goals and tech trends.

Required Academic Background:

• Degree in Computer Science, Software Engineering, or related technical field.
• Equivalent hands-on experience and demonstrable technical mastery may substitute formal education.

Required Skills and Experience:

• 5+ years of professional experience in front-end development, building scalable web applications with modern frameworks.
• Expertise in React and strong knowledge of the JavaScript/TypeScript ecosystem, including component-based architecture, hooks, and state management.
• Solid command of  HTML5, CSS3, and modern layout techniques (Flexbox, Grid), with proven ability to create pixel-perfect, accessible interfaces.
• Understanding of accessibility standards (WCAG) and inclusive design principles.
• Experience with responsive and mobile-first development, ensuring cross-browser and cross-device compatibility.
• Strong understanding of software engineering principles including component reusability, modularity, performance optimization, and maintainability.
• Experience working with RESTful APIs and integrating front-end applications with backend services.
• Skilled in testing strategies with hands-on experience using Jest, Testing Library, and/or Cypress for unit, integration, and E2E testing.
• Familiarity with CI/CD pipelines and version control systems (e.g., Git), with experience in integrating front-end workflows into deployment pipelines.
• Comfortable working in Agile/Scrum environments, participating in ceremonies and collaborating with cross-functional teams.
• Proficiency using collaboration tools like Jira, Figma, Notion, or similar platforms.
• Excellent communication skills, with the ability to articulate technical concepts clearly to non-technical stakeholders and collaborate effectively across distributed teams.
• Bilingual communication capacity, with native-level Spanish and intermediate English proficiency (C1), ensuring effective collaboration in regional and international production contexts.

Nice to have (Not exclusive)

• Experience working with headless architectures and CMS platforms such as Strapi, Contentful, Sanity, or similar.
• Familiarity with static site generators and frameworks like Next.js, Gatsby, or Nuxt.
• Exposure to design systems development, component libraries, and token-based styling.
  
• Experience with web analytics tools and A/B testing frameworks.

Core Competencies:

At our company, we believe that success is not just about technical proficiency but also how you work with others and approach challenges. As part of our team, you’ll be expected to demonstrate the following key competencies:

• Excellent communication and interpersonal skills: Ability to effectively communicate and collaborate with clients and team members. 
• Problem-solving and critical thinking: Ability to manage complex projects and find solutions to ensure project success. 
• Organizational skills: Strong attention to detail and ability to manage multiple clients and projects simultaneously. 
• Resilience and adaptability: Ability to navigate challenges and adapt to shifting client needs. 
• Proactive and resourceful: Anticipate client needs and take initiative to ensure high-quality service delivery. 
  

How to apply: 

If you’re passionate about building performant, scalable front-end experiences and enjoy collaborating across disciplines to solve complex user interface challenges, we’d love to hear from you. To apply, please follow these steps:

• Submit Your CV: Upload an updated and detailed resume highlighting your experience in front-end development, React, JavaScript/TypeScript, responsive design, accessibility, and CI/CD integration.
• (Optional) Include links to your portfolio, GitHub, or live projects that showcase your technical skills, code quality, and attention to UI/UX detail.