Senior Software Engineer - UI Frontend

📍 Job Overview

Job Title: Senior Software Engineer - UI Frontend

Company: Arcesium LLC

Location: Lisbon, Portugal

Job Type: Full-Time

Category: Software Engineering (Frontend/UI)

Date Posted: April 28, 2026

Experience Level: 2-5 years

Remote Status: On-site

🚀 Role Summary

• Develop and implement high-performance, data-intensive user interfaces for financial applications, focusing on virtualized grids and complex workflows.

• Architect and build the Backend for Frontend (BFF) layer using Node.js/TypeScript to optimize data consumption for the UI.

• Contribute to the evolution of a modern UI framework, ensuring parity with legacy systems while enhancing usability and accessibility.

• Collaborate with cross-functional teams, including Product Managers, Designers, and backend engineers, to deliver robust and user-centric solutions.

• Integrate AI-assisted development workflows to streamline component creation and legacy application migration.

📝 Enhancement Note: This role is a Senior Software Engineer position with a strong focus on UI Frontend development within the financial technology sector. The emphasis on "data-dense UIs," "virtualized grids," "complex financial workflows," and "Backend for Frontend (BFF)" patterns clearly indicates a specialized role requiring deep expertise in building sophisticated client-side applications that handle significant data volumes and intricate business logic, typical in FinTech environments. The inclusion of AI-assisted development highlights a forward-thinking approach to software engineering.

📈 Primary Responsibilities

• Architect, develop, and maintain reusable UI components within the company's design system (MUI-based), ensuring consistency and adherence to established patterns.

• Implement advanced UI features such as virtualized grids, real-time status views, and efficient column management for large datasets.

• Design and develop the Backend for Frontend (BFF) layer utilizing Node.js/TypeScript, orchestrating data flow from various backend services to meet frontend requirements.

• Collaborate closely with Product Managers and UI/UX Designers to translate requirements into functional, user-friendly interfaces, driving the rollout of modern UI elements.

• Define and manage API contracts with backend engineering teams, ensuring seamless integration and efficient data exchange for frontend consumption.

• Actively participate in and contribute to AI-assisted development initiatives, including prompt-driven component scaffolding and exploring AI for legacy application migration.

• Conduct thorough testing, including Test-Driven Development (TDD) practices, to ensure the quality, performance, and reliability of frontend applications.

• Work with non-technical stakeholders to review and validate user experience, ensuring the final product meets business objectives and user needs.

📝 Enhancement Note: The responsibilities highlight a blend of core frontend development, architectural contributions (BFF), and proactive engagement with emerging technologies like AI. The emphasis on "data grids," "virtualization," "column configuration," and "filtering at scale" points to the need for robust performance optimization skills when dealing with large financial datasets. The requirement to "define and close API contracts" suggests a significant level of autonomy and collaboration with backend teams, underscoring the senior nature of the role.

🎓 Skills & Qualifications

Education:

Experience:

• 2–5 years of professional experience in software engineering, with a demonstrable focus on frontend development.

Required Skills:

• Proficiency in modern frontend technologies: HTML5, JavaScript, TypeScript, React, and CSS.

• Strong command of core JavaScript concepts, including closures, event loop, prototype chain, and asynchronous programming (async/await).

• Deep understanding of TypeScript, including generics and strict typing.

• Solid grasp of architectural principles such as Backend for Frontend (BFF) patterns, component decomposition, and state management (MobX or equivalent).

• Demonstrated experience in building and optimizing data grids, including virtualization, lazy loading, column configuration, and large-scale filtering.

• Practical experience with Material UI (MUI) and design system principles, including the ability to create accessible and consistent UI components.

Preferred Skills:

• Experience with Node.js/Express for server-side rendering or BFF development.

• Familiarity with web performance optimization techniques.

• Curiosity and practical experience with AI-assisted development tools, such as LLM-based coding assistance and prompt engineering for UI scaffolding.

• Experience in defining and managing API contracts.

• Understanding of accessibility standards and best practices (WCAG).

📝 Enhancement Note: The requirement for 2-5 years of experience positions this role as a mid-to-senior level engineer. The explicit mention of "core JavaScript," "TypeScript generics," "BFF patterns," "state management (MobX or equivalent)," and "data grids with virtualization" indicates a need for engineers who can tackle complex frontend challenges beyond basic component development. The preference for Node.js/Express and AI tools suggests an environment that values full-stack capabilities and embraces modern development methodologies.

📊 Process & Systems Portfolio Requirements

Portfolio Essentials:

• Demonstrate experience in building complex, data-intensive user interfaces, showcasing projects that involve significant data visualization or manipulation.

• Include examples of reusable component libraries or contributions to design systems, highlighting adherence to consistency and maintainability standards.

• Showcase projects that involve architectural patterns like Backend for Frontend (BFF), illustrating how the UI layer was optimized for data consumption.

• Provide evidence of optimizing performance for large datasets, such as virtualized grids or efficient data fetching strategies.

Process Documentation:

• Examples of how you approach Test-Driven Development (TDD) and ensure code quality through automated testing.

• Documentation or explanations of how you've contributed to or maintained design systems, emphasizing consistency and scalability.

• Case studies detailing the architectural decisions made for frontend projects, particularly concerning state management, component architecture, and API integration.

• Instances where you've collaborated with designers and product managers to refine user experience, including feedback loops and iteration processes.

📝 Enhancement Note: For a Senior Software Engineer role focused on UI development, a portfolio should emphasize not just the final product but also the underlying architecture, process, and problem-solving. Demonstrating experience with complex data handling, component reusability, and architectural patterns like BFF is crucial. Evidence of TDD and collaboration with design/product teams will showcase a mature development approach.

💵 Compensation & Benefits

Salary Range:

Benefits:

• Comprehensive health insurance package.

• Opportunities for professional development, including training, certifications, and conference attendance.

• Generous paid time off (vacation, sick leave, public holidays).

• Retirement savings plan or pension contributions.

• Potential for performance-based bonuses.

Working Hours:

• Standard full-time work week, typically around 40 hours. Flexibility may be offered, but the role is on-site, requiring consistent presence during core business hours for collaboration.

📝 Enhancement Note: The salary range provided is an estimate based on market data for Lisbon, Portugal, for a Senior Software Engineer with 2-5 years of experience in the technology sector, specifically considering the FinTech industry which often offers competitive compensation. The benefits listed are standard for established tech companies and are tailored to attract and retain skilled engineering talent. The "on-site" requirement dictates a more traditional working hour structure.

🎯 Team & Company Context

🏢 Company Culture

Industry: Financial Technology (FinTech). Arcesium operates in a high-growth industry characterized by rapid innovation, complex data challenges, and a strong emphasis on security and reliability.

Company Size: Arcesium is a global financial technology firm. While the exact size isn't specified in the provided data, the mention of "expanding operations" and "strategic new business opportunities" suggests a company that is well-established but actively growing, likely employing hundreds to thousands of professionals globally.

Founded: The founding date of Arcesium LLC is not specified in the provided data.

Team Structure:

• The role is within the technology team, specifically focusing on UI Frontend development. This team likely comprises various software engineers, UI/UX designers, product managers, and potentially QA specialists.

• Engineers are expected to work within agile methodologies, collaborating closely with product and design to iterate on features.

Methodology:

• Arcesium emphasizes intellectual curiosity, proactive ownership, and collaboration.

• The company aims to leverage its platform and capabilities to solve complex data-driven challenges for sophisticated financial institutions.

• There's a focus on innovation and continuous improvement, as indicated by the drive to "build next-generation software" and the adoption of AI-assisted development.

Company Website: https://www.arcesium.com/

📝 Enhancement Note: The company description highlights a FinTech firm with a focus on complex data solutions for sophisticated financial institutions. This implies a culture that values precision, analytical rigor, and robust engineering practices. The emphasis on "innovation," "proactive ownership," and "collaboration" suggests a dynamic work environment where engineers are empowered to contribute significantly.

📈 Career & Growth Analysis

Operations Career Level: This is a Senior Software Engineer role. It signifies a level of technical expertise beyond junior or mid-level positions, requiring independent problem-solving, architectural contributions, and mentoring capabilities. The role involves building core platform features and influencing technical direction within the UI domain.

Reporting Structure: The Senior Software Engineer will likely report to an Engineering Manager or a Lead Engineer within the frontend or broader technology team. They will collaborate closely with Product Managers and Designers who may operate on a similar hierarchical level or report into different departments.

Operations Impact: As a Senior Software Engineer, the individual's contributions directly impact the usability, performance, and functionality of Arcesium's platform, which is critical for its clients' ability to manage complex financial data and operations. Enhancements in UI performance, user experience, and the adoption of new technologies like AI can lead to increased client satisfaction, operational efficiency for clients, and a stronger competitive advantage for Arcesium.

Growth Opportunities:

• Technical Specialization: Deepen expertise in frontend architecture, performance optimization, specific JavaScript frameworks, or emerging UI technologies. Potential to become a subject matter expert or architect in UI development.

• Leadership & Mentorship: Progress into a Tech Lead role, guiding a team of engineers, overseeing project execution, and mentoring junior developers.

• Cross-Functional Expansion: Gain exposure to backend development, product management, or AI/ML integration, potentially leading to hybrid roles or specialization in areas like full-stack development or AI-driven UI.

• Domain Expertise: Develop a strong understanding of financial markets and complex data management, becoming invaluable within the FinTech industry.

📝 Enhancement Note: The "Senior" title and the detailed responsibilities suggest a clear path for growth. Engineers in this role are expected to not only deliver but also to influence technical decisions and mentor others. The FinTech context provides a unique opportunity to combine technical prowess with deep industry knowledge.

🌐 Work Environment

Office Type: The role is described as "On-site," indicating a traditional office-based work environment. This suggests a physical workspace designed for collaboration and focused work.

Office Location(s): Lisbon, Portugal. This location offers a vibrant European tech hub environment.

Workspace Context:

• The workspace is likely designed to foster collaboration, with shared team areas, meeting rooms, and potentially open-plan seating arrangements.

• Access to modern development tools, high-performance workstations, and robust network infrastructure is expected, supporting the development of complex software.

Work Schedule:

• The working hours are standard full-time (approx. 40 hours/week), requiring consistent presence at the Lisbon office. While some flexibility might be inherent in modern office settings, the on-site nature emphasizes the importance of in-person collaboration during core business hours.

📝 Enhancement Note: The on-site requirement in Lisbon implies a work environment that values face-to-face interaction, team cohesion, and the benefits of a shared physical workspace for innovation and problem-solving, particularly in a complex field like FinTech.

📄 Application & Portfolio Review Process

Interview Process:

• Initial Screening: A recruiter or hiring manager will review your application and resume for basic qualifications and experience.

• Technical Interview(s): Expect one or more technical interviews focusing on core JavaScript, TypeScript, React, data structures, algorithms, and architectural concepts (BFF, state management). These may include coding challenges or system design questions.

• Portfolio Review/Coding Challenge: You may be asked to present specific projects from your portfolio that demonstrate your skills in building complex UIs, data grids, or using the specified technologies. A practical coding exercise, possibly related to UI component development or API integration, is also likely.

• Behavioral/Team Fit Interview: Interviews assessing your collaboration style, problem-solving approach, ability to work within a team, and cultural alignment with Arcesium's values (intellectual curiosity, ownership, collaboration).

• Final Interview: Potentially with senior leadership or a hiring manager to discuss overall fit, career aspirations, and finalize the decision.

Portfolio Review Tips:

• Curate Selectively: Choose 2-3 projects that best showcase your skills in React, TypeScript, complex data handling (grids, virtualization), and ideally, any experience with BFF patterns or Node.js.

• Highlight Technical Depth: For each project, be prepared to discuss the architectural decisions, challenges faced, solutions implemented, and the specific technologies used (e.g., state management strategies, performance optimizations for data grids).

• Quantify Impact: If possible, use metrics to demonstrate the impact of your work (e.g., "improved rendering performance by X%," "reduced data load times by Y seconds," "enabled Z new features through component reusability").

• Showcase Collaboration: Be ready to discuss how you collaborated with designers, product managers, and backend engineers on your projects.

• Prepare for Live Coding: If a live coding exercise is expected, practice common frontend challenges, focusing on clean, efficient, and well-tested code.

Challenge Preparation:

• System Design: Prepare to discuss how you would design a complex UI feature, considering scalability, performance, maintainability, and API interactions. Focus on BFF patterns for orchestrating data.

• Coding Proficiency: Brush up on JavaScript/TypeScript fundamentals, React component patterns, state management, and common algorithms/data structures. Practice writing clean, readable, and testable code.

• Problem-Solving: Be ready to articulate your thought process for solving technical problems, breaking them down, and evaluating different solutions.

📝 Enhancement Note: The interview process for a Senior Engineer role in FinTech will be rigorous, focusing heavily on technical depth, architectural understanding, and practical problem-solving. A strong portfolio is essential, and candidates should be prepared to articulate their contributions and technical decisions in detail.

🛠 Tools & Technology Stack

Primary Tools:

• Frontend Framework: React

• Languages: JavaScript, TypeScript

• Styling: CSS, Material UI (MUI)

• State Management: MobX (or equivalent like Redux, Zustand)

• Testing: TDD practices, likely using Jest, React Testing Library, or similar.

• Build Tools: Webpack, Vite, or similar module bundlers.

Analytics & Reporting:

CRM & Automation:

Backend for Frontend (BFF):

• Server-side Runtime: Node.js

• Framework: Express.js (preferred) or similar Node.js frameworks.

• API Interaction: Experience with RESTful APIs and potentially GraphQL.

AI & ML Tools:

• Exposure to LLM-based coding assistants (e.g., GitHub Copilot) and prompt engineering for UI scaffolding.

📝 Enhancement Note: The technology stack is modern and focused on building robust, scalable, and performant web applications. Proficiency in React and TypeScript is paramount, with strong architectural understanding (BFF, State Management) being key differentiators. The inclusion of Node.js for BFF and AI tools indicates a forward-looking development environment.

👥 Team Culture & Values

Operations Values:

• Intellectual Curiosity: A drive to learn, explore new technologies, and understand complex financial concepts.

• Proactive Ownership: Taking initiative, identifying problems, and driving solutions independently.

• Collaboration: Working effectively with cross-functional teams, sharing knowledge, and contributing to a positive team environment.

• Innovation: Embracing new ideas, experimenting with cutting-edge technologies like AI, and pushing the boundaries of what's possible in FinTech UI.

• Quality & Reliability: A commitment to building high-performance, stable, and secure software critical for financial institutions.

Collaboration Style:

• Agile development practices are likely employed, fostering iterative development and continuous feedback loops.

• Strong emphasis on cross-functional teamwork, requiring engineers to communicate effectively with product managers, designers, and backend developers.

• Openness to code reviews and constructive feedback to ensure code quality and knowledge sharing.

• A culture that likely encourages the sharing of best practices and problem-solving techniques within the engineering team.

📝 Enhancement Note: The company values emphasize a proactive, learning-oriented, and collaborative approach to software development. This is crucial for a role that involves complex problem-solving and continuous innovation in the FinTech space.

⚡ Challenges & Growth Opportunities

Challenges:

• Handling Data Complexity: Effectively managing and rendering large, complex datasets in a performant and user-friendly manner within financial workflows.

• Bridging Legacy and Modern: Ensuring seamless integration and feature parity between legacy systems and the new, modern UI rollout.

• API Contract Management: Collaborating with backend teams to define and maintain robust API contracts that meet evolving frontend needs.

• Adopting New Technologies: Integrating AI-assisted development tools and workflows smoothly into existing development processes.

• Maintaining Design System Consistency: Ensuring adherence to design principles and component standards across a growing application.

Learning & Development Opportunities:

• Advanced Frontend Architecture: Deepen expertise in complex UI patterns, state management, performance optimization, and architectural design (BFF).

• FinTech Domain Knowledge: Gain significant understanding of financial markets, trading systems, and data management principles.

• AI Integration: Develop practical skills in leveraging AI tools for software development, including prompt engineering and understanding AI capabilities.

• Cross-Functional Skills: Enhance collaboration and communication skills by working closely with product, design, and backend teams.

• Leadership and Mentorship: Opportunities to mentor junior engineers, lead feature development, and potentially move into technical leadership roles.

📝 Enhancement Note: The challenges presented are typical for senior roles in rapidly evolving tech sectors like FinTech. They offer significant opportunities for professional growth and skill development, particularly in areas of high demand like AI integration and complex data handling.

💡 Interview Preparation

Strategy Questions:

• "Describe a complex data grid you've built. What were the key challenges in performance optimization and how did you address them?" (Focus on virtualization, lazy loading, efficient data fetching).

• "How would you approach designing a Backend for Frontend (BFF) layer for a feature that requires data from multiple microservices? What are the trade-offs?" (Focus on orchestration, data transformation, API contracts).

• "Walk us through your process for building a reusable component in a design system. How do you ensure accessibility and consistency?" (Focus on Material UI, design principles, testing).

• "Tell me about a time you had to collaborate with a designer or product manager to implement a challenging UI feature. What was your approach?" (Focus on communication, iteration, problem-solving).

• "How do you approach Test-Driven Development (TDD)? Can you give an example of how you've used it to improve code quality?" (Focus on testing frameworks, mindset, benefits).

Company & Culture Questions:

• "What interests you about Arcesium and the FinTech industry specifically?" (Research Arcesium's mission, products, and recent news. Understand the FinTech landscape).

• "How do you embody intellectual curiosity and proactive ownership in your work?" (Prepare examples from your experience demonstrating these values).

Portfolio Presentation Strategy:

• Choose Relevant Projects: Select projects that highlight your expertise in React,

TypeScript, data grids, and ideally, any architectural patterns like BFF.

• Structure Your Narrative: For each project, clearly articulate:

  • The problem you were solving.
  • Your specific role and contributions.
  • The technical challenges and your solutions.
  • The technologies used and why.
  • The outcome or impact of your work (quantify if possible).

• Be Ready for Deep Dives: Anticipate questions about specific code snippets, architectural choices, performance bottlenecks, and testing strategies.

• Demonstrate Collaboration: Explain how you worked with other team members (designers, backend engineers) throughout the project lifecycle.

📝 Enhancement Note: Interview preparation should focus on demonstrating deep technical expertise, architectural understanding, problem-solving skills, and a collaborative mindset aligned with Arcesium's values. The portfolio is a critical tool for showcasing practical application of these skills.

📌 Application Steps

To apply for this Senior Software Engineer - UI Frontend position:

• Submit your application through the Arcesium careers portal via the provided Greenhouse link.

• Tailor Your Resume: Highlight your experience with React, TypeScript, Node.js, Material UI, data grids, performance optimization, and any FinTech exposure. Quantify achievements where possible.

• Prepare Your Portfolio: Select 2-3 key projects that best demonstrate your skills in building complex UIs, data-intensive applications, and architectural patterns like BFF. Be ready to articulate your contributions and technical decisions in detail.

• Practice Technical Concepts: Review core JavaScript, TypeScript, React fundamentals, data structures, algorithms, and system design principles, especially concerning frontend architecture and BFF patterns.

• Research Arcesium: Understand the company's mission, values, and its position in the FinTech industry to articulate your interest and cultural fit effectively.

⚠️ Important Notice: This enhanced job description includes AI-generated insights and industry-standard assumptions. All details should be verified directly with Arcesium LLC during the application and interview process.