Software Engineering Daily: Deep Dive into Polypane with Kilian Balcoff

In the May 6, 2025 episode of Software Engineering Daily, host Josh Goldberg engages in an insightful conversation with Kilian Balcoff, the founder and creator of Polypane—a specialized web development browser designed to streamline the creation and testing of modern websites. This summary captures the essence of their discussion, highlighting key features, development philosophies, and future aspirations of Polypane.

1. Introduction to Kilian Balcoff and Polypane

Josh Goldberg opens the episode by introducing Kilian Balcoff, shedding light on his journey as a web developer who transitioned from creating jQuery plugins and Python applications to developing a sophisticated browser tailored for developers.

[02:21] Kilian Balcoff: "Polypane is actually like one in a longer line of apps to scratch... Why not just show a bunch of sizes side by side and see how that goes. So that's how Polypane was born."

Kilian emphasizes his passion for creating tools that solve real-world problems faced by developers, setting the stage for the introduction of Polypane.

2. Kilian’s Journey from Web Development to Creating Polypane

Kilian recounts his early days in web development, starting at the age of 11 with basic webpage creation, progressing through experimenting with Flash, and eventually focusing on creating tools that enhance the web development experience. His persistent drive to “never be satisfied” fuels his commitment to continuous improvement in his projects.

[04:03] Kilian Balcoff: "There's always something to improve. There's always something where you go like, oh well maybe I can also do this or this. And that's also what keeps me going."

This relentless pursuit of perfection and efficiency led him to develop Polypane, aiming to address the inherent frustrations in website development and testing.

3. The Genesis of Polypane

Polypane emerged from Kilian’s need to “scratch his own itch”. Frustrated by the constant resizing of browsers to test responsive designs, he envisioned a tool that could display multiple viewport sizes simultaneously. Leveraging technologies like Chromium and Electron, Polypane was born to offer developers a seamless way to test and debug websites across various devices and screen sizes.

[06:05] Kilian Balcoff: "Polypane was just one of them, where I was like, you know, it's super annoying to resize my browser all the time. Why not just show a bunch of sizes side by side and see how that goes."

4. Key Features of Polypane

Kilian delves into the comprehensive feature set of Polypane, highlighting its unique capabilities designed to enhance the web development workflow.

a. Multiple Viewports and Synchronized Interactions

Polypane allows developers to view their websites across multiple devices and screen sizes simultaneously, ensuring consistent design and functionality without the tedious task of manual resizing.

[09:39] Kilian Balcoff: "You can see your webpage, adds all these different sizes, and then also all these different emulation modes... you can test your website in all these different variations that it comes in."

b. Advanced Accessibility Tools

Understanding the challenges of implementing accessibility, Polypane doesn't just identify issues but also provides actionable solutions, making it easier for developers to enhance the accessibility of their websites without needing to be experts.

[13:45] Kilian Balcoff: "I'm going to tell you what's wrong, but then I'm also going to hand you the solution or the fix... you can just copy and paste it and again, like drag the ticket to done and move on with your life."

c. Enhanced Meta Information Inspection

Polypane integrates tools to inspect and manage meta information seamlessly, such as titles, descriptions, and security files, which are crucial for SEO and web standards compliance.

[16:25] Kilian Balcoff: "All these things that surround the visual design... Polypane gives you all these tools and warnings and suggestions on how to improve those things."

d. Custom DevTools

Differentiating itself from standard browsers, Polypane features a bespoke Elements Inspector and Console, enabling developers to make changes that apply across all viewports simultaneously, ensuring uniformity and saving valuable time.

[22:28] Kilian Balcoff: "I built my own Elements Inspector... except that it applies your changes to all the viewports that you're looking at right now."

e. Performance and Cross-Platform Optimization

As a desktop application built on Electron and Chromium, Polypane is optimized for performance, ensuring it remains efficient even during prolonged use. Kilian discusses the importance of maintaining performance and memory management to provide a smooth user experience.

[28:38] Kilian Balcoff: "Polypane is over 10 megabytes and that doesn't matter because like I'm also shipping chromium... But what does become important is that it might be running for like a day."

f. Latest Innovations: Polypane Portal

Addressing the limitations of testing across different browsers and devices, Polypane Portal allows developers to proxy their local servers and interact with multiple devices simultaneously. This feature simplifies the testing process, enabling developers to seamlessly test their websites on various platforms without switching contexts.

[32:13] Kilian Balcoff: "Polypane Portal... you can open that on all your devices and you can have them like laid out on the table and then it's the same thing... you can still interact with all of them through Polypane."

5. Community Engagement and Feature Adoption

Kilian emphasizes the importance of community feedback in shaping Polypane’s development. By publicly acknowledging contributors and integrating highly requested features from industry experts, Polypane stays aligned with the evolving needs of developers.

[39:03] Josh Goldberg: "You have a blog post from November 2024 where someone who's quite well known, Adam Argyle on the Chrome DevRel team asked what it's missing from the Chrome DevTools and you, in this blog post, break down all these different, very common requests and explain exactly how they map to built-in features into Polypane."

Kilian highlights his proactive approach in implementing features that resonate with the developer community, ensuring Polypane remains a vital tool in modern web development.

6. Technical Insights and Challenges

The discussion delves deep into the technical aspects of building and maintaining Polypane. Kilian shares his experiences in developing custom devtools, managing synchronization across multiple viewports, and ensuring compatibility with various web technologies and frameworks like React and Vue.

[21:10] Kilian Balcoff: "I'm sending synthetic events in all the other places and then I'm like tricking React and Vue into still accepting it, even if it's synthetic."

He also touches upon the challenges of keeping up with the rapidly evolving web platform, leveraging Chromium's updates, and ensuring Polypane remains compatible and efficient across different operating systems.

7. Future Directions and Continuous Innovation

Looking ahead, Kilian discusses his commitment to continuous improvement and innovation, inspired by concepts like Kaizen. Polypane Portal and upcoming features aim to further simplify the development and testing processes, making Polypane an indispensable tool for web developers.

[35:37] Kilian Balcoff: "Polypane now also does that for Portal, which means that if you have an app that supports MDNS with HTTP that will show up."

Kilian underscores his dedication to staying ahead of the curve, ensuring that Polypane adapts to the changing landscape of web development technologies and practices.

8. Personal Touch: A Taste for Apple Cider

In a delightful departure from technical discourse, Kilian shares his passion for European apple cider, detailing his experiments with crafting his own liqueurs. This personal anecdote adds a relatable dimension to the conversation, showcasing Kilian's creativity beyond the realm of software development.

[43:42] Kilian Balcoff: "I'm making an ice cider liqueur... it's very tasty. And then I'm going to add some apple molasses... I should have an extremely tasty liqueur."

Kilian's enthusiasm for his hobby reflects his broader approach to problem-solving and experimentation, traits that undoubtedly influence his work on Polypane.

9. Conclusion and Final Thoughts

As the episode wraps up, Kilian invites listeners to try Polypane, emphasizing its accessibility and the value it brings to the development process. His approachable demeanor and openness to feedback reinforce the collaborative spirit behind Polypane's ongoing evolution.

[47:25] Kilian Balcoff: "Anyone listening, please try out Polypane. There's no strings attached... if you have, you know, clever ideas, good suggestions, I'm all yours."

Josh Goldberg thanks Kilian for the engaging conversation, highlighting the insightful exploration of Polypane's features and Kilian's dedication to enhancing the developer experience.

Key Takeaways

• Polypane is a developer-focused browser that simplifies responsive design testing through multiple synchronized viewports.
• It offers advanced accessibility tools that not only identify issues but also provide actionable solutions.
• Custom devtools in Polypane allow for uniform changes across all viewports, enhancing efficiency.
• Performance and cross-platform compatibility are prioritized to ensure a seamless experience for developers.
• Polypane Portal extends functionality by enabling simultaneous testing across multiple devices and browsers.
• Community feedback plays a crucial role in shaping Polypane’s feature set, ensuring it meets the evolving needs of developers.
• Kilian Balcoff’s passion for continuous improvement and innovation drives the ongoing development of Polypane.
• Personal interests, such as crafting apple cider, highlight Kilian's creative and experimental mindset.

Polypane stands out as a powerful tool in the web developer’s arsenal, embodying Kilian Balcoff's vision of making website development and testing more efficient, accessible, and enjoyable.