Performance & Rendering Engineer

About Kaleidos and PenpotKaleidos is the company behind Penpot, the first open source design platform built for design and code teams to work together. We're a horizontal organization, with no traditional hierarchy, and our values are grounded in free software principles, along with honesty, feminism, work-life balance, transparency, generosity, and joy in what we do. At Kaleidos we have a real commitment to diversity in all its forms. Our team is made up of more than 50% women, and we'd love to find new teammates who share our values, who we can keep learning from and keep building Penpot with.What will your work be like?At Penpot we build the design tool that brings together people who design and people who code, within a free, collaborative software environment. We're constantly adding new features that the community and our users ask for, and our challenge is to make all of them as stable and efficient as possible.You'll be part of a small team working in Rust on Penpot's rendering engine (built with WASM, Rust, and Skia), on the text editor, and on ongoing performance improvements. Your work will be focused on fixing bugs, improving performance, and building new features for that engine. Performance is the main focus: help us make Penpot run smoothly in the browser, with response times as fast as possible.You'll also have some points of contact with the frontend, mainly when it comes to passing data between Clojure and the engine. That's why you need to feel comfortable with web programming and with the fundamentals of functional programming.We're looking for someone with senior, solid, consolidated experience, to work within a horizontal team with no manager figure: autonomy and shared decision-making are part of the role.What do we needWe believe that education can be acquired in many ways, not just through a degree. That's why we don't require specific formal education, but we do expect you to have senior experience in the following areas:Rendering engines. Here you'll find WASM, Rust, and Skia (so it's great if you have experience building game engines, graphics libraries, rasterization, GPU pipelines...). You don't need to be an expert in these specific technologies or in graphics APIs, but you should have definetely worked with them before, and feel comfortable getting better at them.Hands-on experience with frontend technologies, with a good command of JavaScript, browser APIs, HTML, and CSS.Regular use of LLMs (Claude, Cursor, ChatGPT, OpenCode...) as part of your way of working, among other things to make it easier for you to interact with and integrate into Penpot's Clojure core. We've brought AI into our development processes and we have open discussions and workstreams focused on finding the best way to use AI, taking into account many different aspects (technological possibilities, digital sovereignty / open source, ethics...).Comfortable working in Linux environments.Languages: high level of spoken and written English and Spanish. We need you to be able to read and write technical documentation and speak functionally in English, since it's the first language for some kaleiders. It's also necessary that you know Spanish (spoken and written), since many team meetings are held in this language.An example of someone who'd fit great with the team: someone with experience in graphics engines or in-browser game development (using graphics APIs); or maybe someone strong in WASM, with C++ or Rust, with an interest in working in graphics environments... does that sound like you? ;) Earn extra pointsFamiliarity with Clojure or other functional languages (Scheme, Lisp...).Knowledge of JavaScript testing (Jest, Cypress...) and end-to-end tests with Playwright.Interest in solving user problems with new languages and frameworks.Interest / knowledge in accessibility and responsible development.Interest / knowledge in design systems and their integration with product development.Previous experience or genuine interest in open-source projects.Use of agile methodologies in a professional environment.Background of collaboration in diverse teams (design, marketing, backend...).Ability to ask the right questions to help product development.Care for testing your own code responsibly (unit, integration, and end-to-end tests), to help reduce production incidents.Who will you be working with?You'll regularly work with Elena, Alex, Belén, Andrey, and Alonso, and you'll be in touch with the other software developers and creators of Penpot within the product team. You'll also have periodic cross-team meetings to keep up with the state of the business and the product with other Kaleidos / Penpot teams.What do we offer?Salary: €60–67k (gross annual salary) Permanent contract. We're looking for someone to stay with us for the long run. Flexible schedule. Even better! We all work from 10am to 2pm CET. You can work the rest of your hours whenever you like.37.5h/week as part of our plan to create a better work-life balance. 100% remote position. We keep an office in Madrid (Spain), though attending in person is optional. You can work remotely from anywhere with a reliable internet connection, as long as you're within CET +/- 1 time zone, or you can choose to come into the office whenever you like. 23 days of paid vacation, plus December 24 and 31, and the option to request 10 extra days of unpaid leave. We're very flexible with your dates, you just need to make sure it works for your team. Choose the holiday calendar of where you live or of our headquarters (Madrid). Continuous learning through internal and external training, conferences, and events (as a rule, we usually cover 100% of the cost). We encourage you to experiment with new best practices! Company-paid language classes (English and Spanish): classes paid for by the company, as part of your working hours. 2 PIWEEKs a year! A PIWEEK is a week-long, open-format hackathon where you pause your daily work and focus, alone or with a team, on a great project. Penpot itself was born in a past PIWEEK! Level up your workspace. We provide a budget every 3 years to renew your equipment, and after 3 years you get to keep the "old" gear! An environment where your opinion matters. We have a consensus-based decision-making culture. You'll quickly find yourself involved in everything happening at Kaleidos. An open source company. Our products are open source and we support the open source ecosystem as much as we can. We're fully committed. Self-organized teams: we believe that providing autonomy and independence is key to personal and collective responsibility. Teams at Kaleidos operate internally with very little hierarchy and enjoy the freedom to organize themselves however works best. Alan health insurance through flexible compensation (coverage only in Spain).What is the process like?First interview (25 min) with the People team: we'll talk about Kaleidos's principles, why this role exists, conditions, benefits, and challenges.You send us your cover letter, which we review together with your CV with the selection committee.Cultural interview, with two colleagues from different departments.Technical interview.Conversation with PabloAt each stage we'll get back to you, whether you're moving forward in the process or not, and your feedback will help us improve our processes. We might take a while to respond, especially in the early stages, since our team is quite small, but we want to treat you with care and attention.¿Quiénes somos?We defend and believe in open-source and proof of this is that our main project, Penpot, reflects that. We’re convinced that technology isn’t neutral. That’s why we like to shake things up and go against the  status quo. Penpot is the open-source design platform for teams that need scalable collaboration between designers and developers. Kaleidos is the company boosting Penpot. If you’re interested in getting a deeper sense of our culture and values, have a look at our website  to gain insight into who we are and what we believe in.