# Scott Jehl

> Scott Jehl is a Senior Software Engineer on the Web Performance team at Squarespace, a 20-year veteran of the front-end web who helped define modern responsive and performant design. He authored 'Responsible Responsive Design' (A Book Apart, 2014) and co-authored 'Designing with Progressive Enhancement' (2010), created foundational open-source tools like Respond.js, loadCSS, and Picturefill, and recently led the effort that brought lazy loading to HTML video and audio elements - an official web standard as of March 2026. He speaks globally, teaches online, and believes the web should work fast for everyone, everywhere.

- **Role:** Senior Software Engineer at Squarespace
- **Organizations:** Squarespace, Filament Group, Catchpoint / WebPageTest, Begin
- **Nationality:** American
- **Known for:** Co-created Picturefill, the polyfill that helped bring responsive images to the web before browsers supported <picture> natively, Created Respond.js, enabling CSS3 media queries in IE 6-8+ and accelerating responsive design adoption, Created loadCSS, enabling async stylesheet loading and dramatically improving page load performance

## Career timeline

- **2010** — Co-authored 'Designing with Progressive Enhancement' (Peachpit/New Riders)
- **2014** — Published 'Responsible Responsive Design' with A Book Apart
- **2012** — Released Respond.js, a CSS3 media queries polyfill for IE 6-8+
- **2013** — Created Picturefill, the responsive images polyfill for the <picture> element
- **2014** — Released loadCSS for asynchronous CSS loading
- **~2007-2022** — Senior Interactive Designer / developer at Filament Group (~15 years)
- **2022-2023** — Senior Experience Engineer at Catchpoint / WebPageTest, led design of WebPageTest Pro Experiments and Carbon Control
- **2023** — Web standards consulting with Begin, focusing on HTML Web Components and the Enhance framework
- **2024** — Joined Squarespace as Senior Software Engineer on the Web Performance Team (June 2024)
- **2024** — Launched 'Web Components Demystified' premium online course
- **2024** — Mystery speaker at SmashingConf New York: 'Web Components Can't Save Us. But You Can!'
- **2026** — Led standardization of loading=lazy for HTML <video> and <audio> elements, officially adopted into the HTML standard on March 23, 2026

## Achievements

- Co-created Picturefill, the polyfill that helped bring responsive images to the web before browsers supported <picture> natively
- Created Respond.js, enabling CSS3 media queries in IE 6-8+ and accelerating responsive design adoption
- Created loadCSS, enabling async stylesheet loading and dramatically improving page load performance
- Authored 'Responsible Responsive Design' (A Book Apart, 2014)
- Co-authored 'Designing with Progressive Enhancement' (2010)
- Led effort to standardize loading=lazy for HTML video/audio elements - adopted as official web standard March 23, 2026
- Delivered 50+ talks and workshops at major international conferences including An Event Apart, SmashingConf, Performance.Now(), Fronteers
- 10 appearances at An Event Apart conferences
- Contributed Web Platform Tests for browser validation of lazy video/audio loading
- Gained formal endorsement from code owners at Mozilla, Apple, and Chromium for HTML standard change

## Latest updates

- **2026-03** — loading=lazy for HTML video and audio became an official web standard, a proposal Scott Jehl led with Squarespace teammates
- **2024-06** — Joined Squarespace as Senior Software Engineer on the Web Performance Team
- **2024** — Launched 'Web Components Demystified' premium online course
- **2024** — Mystery speaker at SmashingConf New York with talk: 'Web Components Can't Save Us. But You Can!'

## Links

- Website: https://scottjehl.com/
- LinkedIn: https://www.linkedin.com/in/scott-jehl/
- Twitter/X: https://x.com/scottjehl
- GitHub: https://github.com/scottjehl

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Profile page: https://yespress.io/scott-jehl
Published by YesPress — https://yespress.io
Last updated: 2026-04-21