Frontend Engineer (Performance & UI Rendering)

Mission:

Transform Nextcloud Office into a high-performance, modern web-based productivity suite, going beyond traditional DOM-driven applications. You will own the look and feel of the product, ensuring that even the most complex documents and spreadsheets remain fast, smooth, and responsive under heavy load.

Responsibilities:

• Build new frontend features such as advanced charts, conditional formatting, and interactive document elements
• Develop fast, responsive user interfaces using modern JavaScript
• Ensure a smooth 60fps experience across all user interactions (scrolling, typing, zooming)
• Move performance-critical rendering logic from the DOM to Canvas or hardware-accelerated technologies
• Refactor legacy styles into a modern, performance-optimized CSS system based on variables (supporting dark mode and high-contrast themes)
• Implement responsive UI patterns such as optimistic UI to improve perceived performance
• Collaborate with other teams to optimize latency and real-time user experience
• Leverage AI tools to accelerate development while focusing on performance, edge cases, and UI quality

Requirements:

Technical

• Strong experience with modern JavaScript (ESNext)
• Deep understanding of DOM behavior and performance trade-offs
• Experience with Canvas API or rendering libraries (e.g., PixiJS or Fabric.js)
• Solid knowledge of frontend performance optimization techniques
• Experience using Web Workers to offload work from the main thread
• Experience with modern CSS and performance-oriented styling

AI & Development

• Experience using AI-assisted development tools (e.g., Cursor or similar)
• Ability to use AI as a productivity multiplier without compromising code quality

Profile

• Strong focus on smooth UI and rendering performance (60fps mindset)
• High level of English proficiency, with strong communication skills in an international team environment
• Attention to detail in user experience and visual quality
• Background in demanding frontend environments (e.g., interactive apps, data visualization, or graphics-heavy web applications)
• Pragmatic, execution-focused mindset

What We Offer:

• Hybrid work model (with preference for our offices in Alcobendas, Valencia, Barcelona, Sevilla, or Logroño)
• Flexible working hours
• Flexible compensation package
• Discounts on Arsys products
• Discounts on technology brands
• Personalized training and development plans
• Biannual team events
• Access to advanced AI tools with no usage restrictions
• Challenging frontend problems in high-performance environments
• Engineering culture focused on quality, performance, and continuous improvement