Senior Full‑Stack Developer: AI‑Powered, Scalable Web Apps

Pack; Barcelona; On-site; EUR 60,000 - 90,000; Full time

Job summary

Pack is seeking a Senior Full Stack Developer to design scalable web applications, optimize performance, and deliver a seamless user experience. The role sits at the crossroads of technical architecture, backend efficiency, and product-minded feature work.

You'll build with SvelteKit, TypeScript, Node.js, PostgreSQL, AWS, SST, Vitest, and Playwright, lead technical discussions, and mentor junior developers while maintaining high standards for code quality and security.

Responsibilities

• Design and implement scalable, efficient features with a focus on maintainable architecture
• Lead technical discussions and make strategic architectural decisions for new and existing features
• Build full-stack solutions with SvelteKit, TypeScript and Node.js, keeping code clean, modular and optimized
• Balance user experience and technical performance to deliver high-quality solutions
• Diagnose and resolve technical issues to keep the system stable and minimize downtime
• Implement robust logging, error handling and monitoring to catch issues proactively
• Refactor and optimize code for performance and scalability, especially on PostgreSQL and AWS
• Manage and optimize AWS infrastructure with SST, keeping it scalable and reliable as usage grows
• Build and maintain CI/CD pipelines for automated testing and deployment
• Streamline deployment processes for smooth rollouts with minimal user disruption
• Design and build AI-powered tools and features that automate workflows and improve the user experience
• Experiment with new technologies to integrate AI solutions that scale manual processes and expand product capabilities
• Lead code reviews focused on edge cases, security and performance
• Set and enforce coding standards, including error handling, input validation and security best practices
• Ensure high test coverage with Vitest and Playwright, including edge cases and exceptional scenarios
• Mentor junior developers and foster continuous learning
• Apply secure coding practices in line with OWASP guidelines
• Regularly assess and fix security vulnerabilities
• Respond quickly and effectively to security incidents
• Monitor system and database performance, identifying and resolving bottlenecks
• Stay current with new tools and technologies and propose improvements to the platform
• Work closely with product managers and designers to align development with business goals
• Provide technical insights and answers on client queries and requirements
• Collaborate with clients and stakeholders to resolve technical issues
• Contribute to a collaborative team culture built on knowledge sharing

Skills

Full-stack development

System design

Mentoring

Tools

SvelteKit

TypeScript

Node.js

PostgreSQL

AWS

SST

Vitest

Playwright

Job description

Pack is seeking a Senior Full Stack Developer to design scalable web applications, optimize performance, and deliver a seamless user experience. The role sits at the crossroads of technical architecture, backend efficiency, and product-minded feature work.

You'll build with SvelteKit, TypeScript, Node.js, PostgreSQL, AWS, SST, Vitest, and Playwright, lead technical discussions, and mentor junior developers while maintaining high standards for code quality and security.