Jobs JavaScript / Front-End

Are you an experienced technical leader ready to shape the future of scalable AdTech platforms? We are seeking a Principal Engineer to drive architectural transformation and lead high-impact projects for a Sweden-based industry innovator.

This is a senior-level role with full remote flexibility across Europe. At Sigma Software, we partner with global leaders to deliver cutting-edge technology solutions that automate and optimize revenue-focused operations. You will work on strategic initiatives, collaborate with cross-functional teams, and influence technical direction in a fast-paced, evolving domain.

Why join us? You’ll have the opportunity to work on globally recognized platforms, contribute to architectural innovation, and enjoy a supportive culture with challenging projects.
 

CUSTOMER

Our Customer is a Swedish AdTech company that transforms the way publishers and advertisers interact. They provide state-of-the-art self-serve advertising platforms that enable seamless, direct transactions between advertisers and some of the world’s largest publishers. Their mission is to make advertising more accessible, automated, and efficient through innovative technology. Together, we serve globally recognized clients, including TripAdvisor, Bloomberg, The Washington Post, Opera, Dow Jones, etc. 

PROJECT

The project represents a strategic transition to a Platform-First, API-driven architecture. The company is moving away from monolithic, client-specific codebases to a standardized ecosystem. As a Senior TypeScript/Vue.js Developer, you will be the technical visionary for the platforms, ensuring the technology remains high-performing and scalable.

Job Description

• Act as a key technical liaison between business and engineering teams, translating commercial goals into actionable technical solutions
• Evaluate publisher technical environments and design scalable, maintainable architectures
• Prepare client-ready solution proposals, including features, integrations, and tools
• Lead cross-functional delivery teams, including developers, designers, DevOps, and technical PMs
• Provide architectural oversight throughout the development lifecycle to ensure continuity and quality
• Manage distributed teams across multiple time zones
• Mentor engineers, conduct code reviews, and guide technical growth
• Make architectural decisions at component and plugin levels, balancing trade-offs and communicating choices clearly

Qualifications

• At least 6+ years of hands-on experience in JavaScript / TypeScript, Vue.js, and Node.js
• Experience in microservices architecture and distributed systems integration
• Hands-on experience with AWS Lambda or similar serverless technologies
• Deep understanding of plugin-based systems and extensibility points
• Proven ability to customize and extend existing solutions without breaking core functionality
• Experience in AdTech environments with evolving requirements
• Knowledge of Vite, Cypress, and Vitest for modern development workflows and testing
• Experience with AWS S3 and CloudFront for scalable storage and content delivery
• Strong commercial acumen and ability to translate business goals into technical infrastructure
• Fluent English communication skills for enterprise stakeholder management

WILL BE A PLUS

• Experience with other serverless frameworks (e.g., Azure Functions, Google Cloud Functions)
• Familiarity with enterprise e-commerce platforms
• Knowledge of performance optimization and security best practices
• Prior work in media publishing technology solutions

PERSONAL PROFILE

• Proactive, solution-oriented mindset
• Strong problem-solving skills and ability to unblock dependencies
• Comfortable working in fast-paced environments with evolving requirements
• System-thinking approach — seeing beyond individual tasks to the bigger picture

We are looking for a Frontend Engineer to help build Fillx, a fintech product focused on crypto market workflows and trading operations.

You will work on production-facing web interfaces where clarity, performance, and reliability matter. The role is a good fit for someone who enjoys turning complex market data and operational flows into clean, fast, maintainable user experiences.

Responsibilities:

- Build and maintain React + TypeScript web interfaces.

- Work with real-time or frequently updated market and trading data.

- Design reusable UI components and predictable frontend state flows.

- Collaborate closely with backend/product stakeholders on API contracts and user workflows.

- Keep the frontend codebase readable, tested, and easy to extend.

Requirements:

- Strong experience with React and TypeScript.

- Solid understanding of browser performance, async data loading, and state management.

- Ability to build polished, practical interfaces for data-heavy workflows.

- Experience working with REST APIs and production web applications.

- Clear written communication and ownership of implementation details.

Nice to have:

- Experience with fintech, crypto, trading, or market-data products.

- Experience with charts, dashboards, WebSocket/polling flows, or high-frequency data updates.

- Familiarity with testing frontend behavior and TypeScript-heavy codebases.

Work format:

- Full remote.

- Product-focused team.

- English communication at an intermediate level or higher.

Mate academy is an EdTech company with a gamified, AI-powered LMS platform where people learn IT specialties.

🌎 We’ve successfully launched in Poland and Brazil, and we’re just getting started.

🤘 6000+ graduates have landed their first IT jobs after only 4 months of training.

Our goal is to expand our operations to Brazil. So we are looking for a Full Stack (Frontend) Mentor who will be responsible for mentoring students in the Portuguese language.

What we offer:

• Fast-track career - many of our now-senior developers started their journey with Mate academy as mentors.

• A well-coordinated, international team - always eager to help.

• Hourly payment and flexible schedule - your mentoring week will include 10+ hours of work that can be distributed throughout the week.

Your responsibilities:

• Checking homework assignments of FT course students.

• Answering student questions in chat and on Google meet calls

• Conducting mock technical interviews for students.

• Improving the student learning process.

Our requirements:

• 1 year of commercial experience as a Full Stack (Frontend) developer

• English - B1 or higher, Portuguese - Native 

• Ability to communicate with people and help them solve problems.

• Effective time planning and the ability to organize your own schedule independently.

Recruitment process:

1. Send your CV.

2. Attend a 15-minute call with our coordinators to align expectations (in Portuguese).

3. Do the test task.

4. Attend a tech interview (in English).

Does this offer match your career goals? Then let's get acquainted!

Please, pay attention!
 

This role is open ONLY to EU/USA/Canada/Turkey citizens. 

We're looking for an experienced Front-End Engineer to join the team on a long-term external project. The client is a major European alliance delivering high-tech solutions for the Defense Industry. You'll be part of building impactful, secure, and innovative tech. 

Required skills & stack:
 

• React 18+ with TypeScript in strict mode across all layers.
• Next.js and/or TanStack Router; solid understanding of static/CSR vs SSR trade-offs.
• Hands-on experience working with OpenAPI-generated typed API clients (no ad-hoc fetch).
• TanStack Query (React Query) — server state, caching, request deduplication.
• Form handling with TanStack Form or React Hook Form, schema-aligned validation.
• Component-driven development with Storybook; design tokens / design system consumption.
• Strong testing discipline: unit (Vitest/Jest), component, Playwright E2E, visual regression (Percy).
• Modern CI/CD: lint, type-check, bundle budget, contract tests in pipeline.
• Strong written English; comfortable working async with the client and international teams.
• Pragmatic approach to AI-assisted SDLC (scaffolding, test generation) while keeping business logic human-authored.
• Security-conscious mindset; never bypasses review or testing gates.
• Full end-to-end ownership — from PR to production smoke tests.
   

Nice-to-have:

• Prior experience with external IV&V or security accreditation processes.
   

Tasks to perform:

• Build a production-grade UX/UI prototype covering the complete innovator application journey.
• Implement a scalable, API-driven frontend architecture against an OpenAPI-generated client.
• Own component-level quality: tests, accessibility, visual regression, Lighthouse performance.
• Contribute to the shared design system and BYOF token kit for adoption by member-state teams.
• Enforce structural separation of concerns — no business logic, authorisation, or sensitive data in UI.
• Implement local-first persistence (drafts, offline continuity) without exposing sensitive data client-side.
• Participate in consumer-driven contract tests (Pact) on the FE side of the CI pipeline.
• Triage and resolve IV&V findings within sprint windows.
• Support PI-boundary TEVV sessions with QA and Project Y stakeholders.

Please, pay attention!

This role is available ONLY to EU/USA/Canada/Turkey citizens. 

We're seeking an experienced Front-End Engineer to extend the team for a long-term external project. The client is a big European alliance that provides high-tech solutions for the Defense Industry.
You will be a part of impactful, secure and innovative tech solutions.

Required skills & stack:
 

• React 18+ with TypeScript in strict mode across all layers.
• Next.js and/or TanStack Router; deep understanding of static/CSR vs SSR trade-offs.
• Hands-on experience consuming OpenAPI-generated typed API clients (no ad-hoc fetch).
• TanStack Query (React Query) — server state, caching, request deduplication.
• Form handling with TanStack Form or React Hook Form, schema-aligned validation.
• Component-driven development with Storybook; design tokens / design system consumption.
• Strong testing discipline: unit (Vitest/Jest), component, Playwright E2E, visual regression (Percy).
• Modern CI/CD: lint, type-check, bundle budget, contract tests in pipeline. 
• Strong written English; comfortable working asynchronously with the client and international teams.
• Pragmatic about AI-assisted SDLC (scaffolding, test generation) while keeping business logic human-authored.
• Security-aware mindset; does not bypass review or testing gates.

• Ownership end-to-end — from PR to production smoke tests.

   

Nice-to-have:

• Experience working with an external IV&V or security accreditation process.

Tasks to perform:

• Build the production-grade UX/UI prototype, implementing the complete innovator application journey.
• Implement the scalable, API-driven frontend architecture against an OpenAPI-generated client.
• Own component-level quality: tests, accessibility, visual regression, Lighthouse performance.
• Contribute to the shared design system and the BYOF token kit so member-state teams can adopt it.
• Enforce structural separation of concerns — no business logic, authorisation, or sensitive data in UI.
• Implement local-first persistence (drafts, offline continuity) without leaking sensitive data client-side.
• Participate in consumer-driven contract tests (Pact) on the FE side of the CI pipeline.
• Triage and resolve IV&V findings within sprint windows.
• Support PI-boundary TEVV sessions with QA and Project Y stakeholders.
   

We offer:

- An interesting, influential project;

- Long-term cooperation with a full-time involvement;

- Flexible work schedule and Remote cooperation;

- Professional development with an individual plan of growth;

- Stable salary and planned reviews;

- Paid vacation and sick leaves;

- Corporate team building & workshops, trainigs;

- Excellent team of dedicated professionals;

- Development budget for each employee;

- Strong corporate culture.