Senior Frontend Engineer at Stack AI | Spain

About Stack AIStack AI is on a mission to make Large Language Models accessible to everyone through an intuitive no-code platform that seamlessly integrates leading AI models (OpenAI, Anthropic, Google), various data sources (OneDrive, Google Drive, Notion), and essential SaaS tools. With the backing of Y Combinator and Gradient Ventures, we have amassed thousands of users and secured hundreds of paying clients, including prominent public companies and unicorns.The RoleWe are seeking a talented Senior Frontend Engineer who excels in execution. This role focuses on optimizing and enhancing existing features rather than creating flashy new ones. You will collaborate closely with our Product Design team to transform detailed visual specifications into clean, production-ready code.Main Mission: Alleviate bottlenecks within our Product Design team by taking charge of incremental UX/UI enhancements to our current features and codebase.What You'll DoOptimize and enhance existing frontend code and features.Implement gradual UX/UI enhancements based on detailed design specifications (no design skills required).Work independently with minimal code review—your code should be clean and dependable enough for others to trust without hesitation.Collaborate with Product Designers and Engineers to ensure effective execution.Focus on impactful improvements that enhance product quality and user experience.Refactor and improve legacy code.What We're Looking ForMust-haves:Exceptional code quality: Produce clean, maintainable, and trustworthy code that requires minimal review.Strong execution: Ability to ship quickly and effectively.Senior-level experience: Over 5 years of experience with React, TypeScript, Next.js, and modern frontend technologies.Accountability: You take ownership of your decisions and act responsively.Autonomy: You can manage features from start to finish without needing guidance.Pragmatism: You are ready to engage in detail-oriented, iterative work critical to product success.Technical excellence: A mentor who can share knowledge rather than someone who needs to be taught.Nice-to-haves:Experience with additional frameworks or tools.Familiarity with agile methodologies.Passion for user experience and design.

About Us:At Wizeline, we are a premier global technology solutions provider specializing in AI-native digital products and platforms. Our mission is to empower organizations by harnessing data and AI to expedite their market presence and transform their operations. We pride ourselves on fostering an innovative culture that emphasizes growth, collaboration, and impact.With the right talent and innovative ideas, the possibilities are endless.Are You the Right Fit?If this sounds exciting, let’s see if you align with the following:

About UsAt Visium, we empower enterprise leaders to craft their AI and data strategies, drive transformative initiatives, and effectively integrate AI into their operations—ensuring that their organizations are resilient and future-ready. As a spin-off from Visium, we are channeling our extensive enterprise knowledge into a groundbreaking product: a category-defining Agentic AI solution tailored specifically for pharmaceutical companies.Our product is anchored in AI designed for highly regulated sectors, operating where complexity, compliance, and trust are paramount. Our mission is clear: to expedite the delivery of life-saving medications to the market, making the process faster, more cost-effective, and safer, thereby unlocking significant benefits at scale.With deep roots in enterprise AI and an ambitious vision for the future, we are building a team of innovators, engineers, researchers, and product thinkers to shape a product that is not only technically superior but also transformative.Join us on a mission to redefine the future of work, creativity, and knowledge. Are you ready to help us construct the future of Agentic AI?Role OverviewWe are in search of a Full-Stack Software Engineer eager to help us create the foundation of our Agentic AI Platform from the ground up. You will translate cutting-edge AI concepts into real, production-ready software utilized by scientists and researchers daily.Your responsibilities will encompass the entire stack: from developing intuitive frontends that simplify complex AI systems to designing robust APIs and backend services that facilitate autonomous agents. You will work collaboratively with ML engineers, product designers, and domain experts to forge a platform that merges human expertise with intelligent automation.This role is hands-on and impactful, granting you significant ownership. You will play a critical role in making architectural decisions, experimenting with innovative agentic frameworks, and helping to establish what “state-of-the-art” signifies in the realm of trustworthy AI for life sciences.If you thrive in dynamic environments, are passionate about creating groundbreaking solutions, and aspire to influence the next generation of intelligent software, we would be excited to connect with you.Your daily activities might include:Designing and implementing full-stack features that bring agentic workflows to life for scientists and researchers.Creating orchestration layers, retrieval pipelines, and APIs for intelligent agents using Python and FastAPI.Developing user-friendly and high-performance frontends in React and TypeScript for configuring and monitoring AI agents.Collaborating with ML engineers to integrate LLMs, embeddings, and RAG systems into production settings.Building and maintaining cloud-native infrastructure using containers, Kubernetes, and CI/CD automation.Contributing to architectural decisions, SDK design, and enhancing the developer experience.

Join Version 1 as a Senior Full Stack Engineer and play a pivotal role in developing innovative software solutions that drive our business forward. You will collaborate with cross-functional teams to design, implement, and maintain robust applications while leveraging your expertise in both front-end and back-end technologies. If you are passionate about coding, love tackling complex challenges, and are eager to work in a dynamic environment, we want to hear from you!

jobgether is looking for a Senior Full Stack Engineer based in Spain. This role centers on building and maintaining both front-end and back-end systems that support the company’s job search platform. Role overview As a Senior Full Stack Engineer, the focus will be on designing, developing, and supporting applications that deliver a smooth and responsive user experience. The position involves working across the technology stack to ensure applications perform reliably and efficiently. What you will do Design and implement features for both front-end and back-end systems Maintain and improve application performance and responsiveness Work with cross-functional teams to deliver software that meets user needs Requirements Strong background in software development Proficiency in multiple programming languages Solid understanding of web technologies This position supports jobgether’s mission to simplify job searching by delivering reliable and user-friendly software solutions.

About the Role anyone-ai is looking for a Full-Stack Developer focused on AI training. This position is based in Spain. The role calls for experience across both front-end and back-end development to build and support software that helps train AI systems. What You Will Do Design, code, test, and maintain software applications that support AI training projects Work with cross-functional teams to improve user experiences Contribute to both front-end and back-end solutions Location This is a Spain-based position.

Join Groupon, a leading marketplace where customers explore new experiences and services daily, and where local businesses thrive. We have partnered with over a million merchants worldwide, connecting more than 16 million customers with deals across diverse categories. In a landscape often dominated by e-commerce giants, Groupon stands out as one of the few platforms genuinely committed to propelling local businesses forward based on performance.We are on an exciting journey to radically transform our business through a relentless focus on results. Despite having thousands of employees across multiple continents, we foster a culture that inspires innovation, rewards risk-taking, and celebrates success. Here, your impact can be immediate due to our scale and the rapid pace of our transformation. We blend the best of both worlds: we have the resources and scale of a large company, yet we empower individuals to have significant autonomy and drive meaningful change.About the RoleHybrid from Madrid or ValenciaAs a Full Stack AI Engineer, you will engineer the foundation of our proprietary internal platform that democratizes AI across the organization. This role goes beyond standard full-stack duties; you will construct the framework that enables various teams to develop autonomous AI agents. Your responsibilities will include designing reasoning flows, integration layers, and agent logic that empower AI to execute complex business tasks at scale. This is applied AI engineering: focusing on sophisticated system design and relentless execution rather than model fine-tuning. You will collaborate daily with a newly formed team of engineers and work closely with the AIGO team and cross-functional partners across Global Operations, Customer Satisfaction, and Engineering.

Join Our Team:At INFINIT, we are seeking a talented Full Stack Software Engineer to be an integral part of our dynamic product development team. You will play a crucial role in transforming business objectives into tangible, high-quality software solutions.About Us:Founded in 2023, INFINIT is a rapidly expanding fintech scale-up with operations across Europe and the Americas. We are committed to revolutionizing the SME sector through cutting-edge AI technology. Our comprehensive operating system centers around banking, equipping small business owners and their teams with the tools they need to efficiently manage and enhance their operations.By focusing on niche industries, INFINIT provides customized, high-impact solutions while innovating AI-driven products that unlock substantial growth for our clients. Our ambitions are global, aiming to redefine the fintech landscape for SMEs worldwide.Embark on the INFINIT journey as we reshape the SME economy and create meaningful change through innovation!

Join Version 1 as a Senior Full Stack Engineer and be part of a dynamic team that is dedicated to delivering innovative digital solutions. You will play a crucial role in the development of full-stack applications, utilizing the latest technologies in the digital, data, and cloud sectors. Your expertise will contribute to crafting scalable solutions that meet client needs.

At Affirm, we are on a mission to transform credit into a more transparent and customer-friendly experience. We empower consumers with the flexibility to buy now and pay later without any hidden fees or compounding interest.Join our Acquisition & Onboarding team as a Staff Full Stack Software Engineer within the Consumer organization. This pivotal leadership role is ideal for an engineer who can establish technical direction, influence architectural decisions, and enhance the quality and speed of full stack development across mobile, web, and backend systems. Your work will lay the foundation for the first interactions our customers have with Affirm, fostering trust, clarity, and value from the outset. As a Staff Engineer, you will design long-term technical strategies, mentor senior engineers, and amplify our team's impact through your technical expertise, operational excellence, and navigational skills in uncertain situations. Collaborate with product, design, and engineering to deliver seamless, high-performance, and accessible user experiences that drive conversion, retention, and business growth.

Ebury empowers ambitious businesses to achieve global growth, and we apply the same philosophy towards our team members. We promote innovation, collaboration, and problem-solving within a culture that values belonging, support, and empowerment for everyone to succeed.If you are a collaborative individual eager to revolutionize business operations globally, we invite you to connect with us. Let's discuss how Ebury can elevate your career and help you shape the future.Senior Full-Stack Developer - FintechMálaga Office - Hybrid: 4 days in the office, 1 day remoteBecome a part of our Technology Team at Ebury’s Málaga Office.Impact-Driven Senior Full-Stack Developer Needed: Shape the Future of Our Client Platform with Your ExpertiseAre you passionate about fostering growth in the digital financial ecosystem? Do you thrive in a culture where you can take full ownership of product development and focus on results? Elevate our client trading and payments platform as a Senior Full-Stack Developer and deliver top-notch solutions to our global clients alongside our vibrant teams in South America and Europe.We seek individuals with the right attitude, a strong work ethic, and an entrepreneurial spirit who are willing to tackle challenging questions. You should be guided by data while being driven to solve customer issues. A natural curiosity and a commitment to continuous learning are essential. You should be proficient in various programming languages, frameworks, and tools, with well-informed opinions on the best solutions to address our most significant challenges.Why Join Ebury?Looking to thrive in a high-growth environment? We are in a constant state of expansion. Do you aspire to create a better world? We advocate for inclusion and stand firm against all forms of discrimination. We have zero tolerance for intolerance and celebrate the diversity that contributes to our success as a modern organization.At Ebury, you will find an internal group dedicated to discussing how to promote a diverse and inclusive workplace for all members of the Technology Team. If you’re excited about this job opportunity but feel your background doesn’t perfectly align with the job description, we encourage you to apply anyway. You might be the ideal candidate for this or other positions we have available.Prepare to Elevate Your Career:In our Tech team, your professional growth is paramount. Thanks to our career development programs, you will have the opportunity to advance your skills and expertise.

Join Veeva Systems, a trailblazer in the industry cloud, on our mission to accelerate the delivery of therapies to patients. As one of the fastest-growing SaaS companies, we achieved over $3 billion in revenue last year, with significant growth opportunities ahead. At Veeva, our core values include Doing the Right Thing, Ensuring Customer Success, Promoting Employee Success, and Emphasizing Speed. In 2021, we became a public benefit corporation, committed to balancing the interests of our customers, employees, society, and investors. As a Work Anywhere company, we empower you to choose whether to work from home or in the office, enabling you to thrive in your preferred environment. Join us in transforming the life sciences sector, and making a positive difference for our customers, employees, and communities.The Role Are you excited about creating impactful products in a greenfield environment? We aim to develop a data stewardship platform to enhance OpenData's data curation workflows, allowing Product Managers and over 1,000 data stewards globally to meet their data coverage and quality objectives. As a Full Stack Software Engineer, you will work alongside a talented team of engineers to design and implement features from concept to deployment. You will thrive in an agile environment, making a direct impact on users in a rapidly expanding, market-leading life sciences organization.

Role overview psicro seeks a Full-stack Developer in Madrid to support the development of AI-driven software products. This position covers both front-end and back-end responsibilities, contributing throughout the software development lifecycle. What you will do Build and maintain features for AI solutions, handling both client-side and server-side tasks Work closely with colleagues from various backgrounds to deliver dependable software Turn client requirements into scalable, maintainable technical solutions Requirements Background with modern web technologies and frameworks Strong teamwork and clear communication skills Interest in artificial intelligence and its real-world uses This role is located in Madrid.

ResilientCo is looking for a Full Stack Engineer in Madrid to help build and improve applications across both front-end and back-end systems. This position involves working closely with colleagues from different areas to deliver projects that support the company's technology goals. Role overview This role focuses on developing features and maintaining systems that serve users and internal teams. Expect to contribute to both user interfaces and server-side logic as part of a collaborative group. Collaboration Full Stack Engineers at ResilientCo participate in team discussions and planning, sharing ideas to improve how applications look and function. Working with designers, product managers, and other engineers is a regular part of the job. Location This position is based in Madrid.

N-iX is seeking a Senior Full-Stack Engineer (Spanish-speaking) to enhance our dynamic team.Our client stands as one of the foremost global fashion retailers, operating across more than 200 markets through a blend of e-commerce platforms and thousands of physical stores worldwide. This company expertly manages the entire fashion value chain—from design and manufacturing to distribution and retail—emphasizing flexibility, digital integration, and sustainability.Technology is pivotal in all facets of the business, including stores, e-commerce, logistics, and supply chain. Our engineering teams operate in small, autonomous product teams, taking full ownership of the solutions they develop. Engineers are encouraged to grasp the broader business context, engage directly with stakeholders and users, and play an active role in technical and product decisions.

About the CompanyJoin a dynamic and innovative SaaS company that is revolutionizing the way leading consulting firms and researchers acquire insights. Our client’s state-of-the-art survey platform empowers users to swiftly craft high-quality surveys, enhance collaboration, and achieve impactful results—all while avoiding the pitfalls of outdated tools and processes. Trusted by top consultancies worldwide, they are on a mission to expand their team to develop high-value features and improve code quality.The RoleOur client is in search of a Senior Full-Stack Engineer to become a pivotal member of a small yet highly skilled engineering team. The ideal candidate is a versatile generalist with extensive expertise in TypeScript, who flourishes in an environment characterized by autonomy and minimal meetings. You will be instrumental in both developing new products and enhancing a solid existing codebase, with a focus on maintaining engineering excellence and clean coding practices.What You’ll Do Innovate and implement new features across the entire stack (frontend + backend). Work collaboratively with senior engineers, product managers, and leadership. Engage in a thorough code review process that emphasizes quality and maintainability. Take ownership of projects from conception to deployment in a remote-first, asynchronous work environment.

Join Affirm in our mission to transform credit into a more transparent and user-friendly experience. Our innovative approach allows consumers to buy now and pay later without hidden fees or compounding interest.We are looking for a Full Stack Software Engineer to become a key member of our Card Acquisition team within the Consumer organization. This position is ideal for an engineer eager to enhance the quality and speed of full stack development across mobile, web, and backend systems. You will play a vital role in shaping our customers' first interactions with Affirm, fostering trust, clarity, and value from the outset. As a Software Engineer, you will implement features, engage in technical discussions, and deepen your technical expertise. Collaborating at the intersection of product, design, and engineering, you will create polished, high-performance, and accessible user experiences that significantly influence conversion, retention, and overall business growth.

About UsPerk (formerly TravelPerk) is the leading intelligent platform dedicated to travel and spend management. Designed to alleviate the burdensome, manual tasks that hinder productivity, our innovative tools automate everything from travel bookings to expense management, invoice processing, and beyond. By eradicating the shadow work that squanders valuable hours, diminishes morale, and stifles creativity, we aim to empower genuine work that makes a tangible difference.With the trust of over 10,000 companies globally, including industry leaders such as Wise, On Running, Breitling, and Fabletics, we are committed to addressing the 7 hours of lost productivity per employee each week, which amounts to a staggering $1.7 trillion challenge.Founded in 2015, Perk has expanded into a vibrant global entity with over 1,800 employees across 12 offices, including our headquarters in London and Boston. We blend innovation, control, and simplicity to revolutionize how businesses operate and enhance workplace satisfaction.At Perk, our core values drive us—embracing ownership, delivering a 7-star experience, and collaborating as one unified team. We prioritize curiosity, purpose, and mindset over mere knowledge to unleash your full potential. Our talent team is a mosaic of prominent professionals from the travel and SaaS sectors, representing over 70 countries. If you're passionate about creating a real impact and redefining how millions experience work, we would be thrilled to welcome you to our team.Learn more about us at www.perk.com.The Platform team at Perk lays the groundwork that the rest of the company relies on. We oversee shared infrastructure, core services, and developer tools that enable product teams to innovate swiftly without compromising quality. Although our work often occurs behind the scenes, its effects are ubiquitous—enhancing reliability, scalability, security, and the overall developer experience.We tackle complex, systemic challenges, make informed trade-offs, and hold ourselves accountable for the platform's long-term health. If you value leverage, clean abstractions, and building robust systems, we want to hear from you!

About ExoticcaExoticca is a trailblazing online travel agency that has transformed the way we conceive, produce, and sell long-distance dream vacations. Central to Exoticca's brand is our unwavering commitment to crafting unforgettable life experiences. We excel in offering exceptional value trips, uncovering unique destinations, and curating extraordinary travel adventures, all while demonstrating genuine care for our customers and the planet.As a dynamic, multicultural team experiencing rapid international growth, we are actively seeking talented partners to help us shape the best and most innovative travel company of our generation.What We OfferAs a Full Stack Engineer, you will have the opportunity to design and develop modern, scalable services utilizing NextJS, Node.js, TypeScript, and MongoDB.You will create robust, maintainable services that fuel our platform, ensuring optimal performance, reliability, and seamless integration across various systems.Your technical expertise and innovative thinking will contribute to the development of a modular, event-driven architecture (EDA) that facilitates efficient communication between services while supporting the ongoing growth and evolution of our e-commerce platform.Key ResponsibilitiesArchitect and develop scalable services, contributing to the advancement of a modern, event-driven architecture.Collaborate with cross-functional teams to translate business requirements into reliable, efficient, and extendable technical solutions.Implement and maintain clean service interfaces and data flows according to EDA principles, ensuring smooth inter-component communication.Produce high-quality, testable code supported by automated testing and continuous integration pipelines.Engage in code reviews, architectural discussions, and technical design sessions to uphold engineering standards and encourage knowledge sharing.Continuously enhance system design and development methodologies to support the scalability and future growth of the platform.

Jobgether is looking for a Senior Full-Stack Engineer with strong experience in Python and React. This position is based in Spain and centers on building and maintaining web applications that improve how users interact with our platform. What you will do Design, develop, and maintain web applications using Python and React Work closely with team members to deliver features that enhance the user experience Contribute to technical decisions and help set the direction for ongoing projects Mentor junior developers and support their growth Requirements Strong knowledge of both front-end and back-end development Proficiency in Python and React Experience working in an agile team setting Ability to collaborate effectively and communicate technical concepts clearly