Ethan Gardner
@ethangardner.com
I'm a full stack engineer with a bias toward the front-end. Web performance optimization, accessibility, and all that jazz.
Reposted by Ethan Gardner
*quietly*
Out today: USWDS 3.14.0. github.com/uswds/uswds/...
The USWDS open source community and scarce part-time staff are _incredible_, just sayin’.
Out today: USWDS 3.14.0. github.com/uswds/uswds/...
The USWDS open source community and scarce part-time staff are _incredible_, just sayin’.
Releases · uswds/uswds
The U.S. Web Design System helps the federal government build fast, accessible, mobile-friendly websites. - uswds/uswds
github.com
August 19, 2026 at 3:22 AM
*quietly*
Out today: USWDS 3.14.0. github.com/uswds/uswds/...
The USWDS open source community and scarce part-time staff are _incredible_, just sayin’.
Out today: USWDS 3.14.0. github.com/uswds/uswds/...
The USWDS open source community and scarce part-time staff are _incredible_, just sayin’.
If you're optimizing your site for AI, the AI wants:
- A fast Time to First Byte (200-500ms).
- Server-rendered HTML
- Lightweight markup
- A valid accessibility tree
- Layout stability
- Captions and alt text
- No stupid CAPTCHAs
Sound familiar? That's the same stuff that human users want too.
- A fast Time to First Byte (200-500ms).
- Server-rendered HTML
- Lightweight markup
- A valid accessibility tree
- Layout stability
- Captions and alt text
- No stupid CAPTCHAs
Sound familiar? That's the same stuff that human users want too.
August 12, 2026 at 3:40 AM
If you're optimizing your site for AI, the AI wants:
- A fast Time to First Byte (200-500ms).
- Server-rendered HTML
- Lightweight markup
- A valid accessibility tree
- Layout stability
- Captions and alt text
- No stupid CAPTCHAs
Sound familiar? That's the same stuff that human users want too.
- A fast Time to First Byte (200-500ms).
- Server-rendered HTML
- Lightweight markup
- A valid accessibility tree
- Layout stability
- Captions and alt text
- No stupid CAPTCHAs
Sound familiar? That's the same stuff that human users want too.
Reposted by Ethan Gardner
Presenting a Web Performance MasterClass at the WeAreDevelopers World Congress
I will be presenting an all-day Web Performance MasterClass at the WeAreDevelopers World Congress in San Jose, CA from September 23-25, 2026. I have a discount registration codes available if you're interested in…
I will be presenting an all-day Web Performance MasterClass at the WeAreDevelopers World Congress in San Jose, CA from September 23-25, 2026. I have a discount registration codes available if you're interested in…
Presenting a Web Performance MasterClass at the WeAreDevelopers World Congress
I will be presenting an all-day Web Performance MasterClass at the WeAreDevelopers World Congress in San Jose, CA from September 23-25, 2026. I have a discount registration codes available if you're interested in attending.
aarontgrogg.com
August 11, 2026 at 3:37 AM
Presenting a Web Performance MasterClass at the WeAreDevelopers World Congress
I will be presenting an all-day Web Performance MasterClass at the WeAreDevelopers World Congress in San Jose, CA from September 23-25, 2026. I have a discount registration codes available if you're interested in…
I will be presenting an all-day Web Performance MasterClass at the WeAreDevelopers World Congress in San Jose, CA from September 23-25, 2026. I have a discount registration codes available if you're interested in…
Reposted by Ethan Gardner
I've just release v6.0.0 of the web-vitals library.
It includes support for measuring Web Vitals per soft navigation (like those used in SPAs) for supporting browsers (Chrome 151+) to give more accurate performance metrics for those sites.
github.com/GoogleChrome...
It includes support for measuring Web Vitals per soft navigation (like those used in SPAs) for supporting browsers (Chrome 151+) to give more accurate performance metrics for those sites.
github.com/GoogleChrome...
github.com
July 21, 2026 at 7:51 PM
I've just release v6.0.0 of the web-vitals library.
It includes support for measuring Web Vitals per soft navigation (like those used in SPAs) for supporting browsers (Chrome 151+) to give more accurate performance metrics for those sites.
github.com/GoogleChrome...
It includes support for measuring Web Vitals per soft navigation (like those used in SPAs) for supporting browsers (Chrome 151+) to give more accurate performance metrics for those sites.
github.com/GoogleChrome...
I don't know if this article will resonate or not, but I felt it necessary to write. I explore the risks of AI software development, defects, and the challenges of building a mental model when the agent does more and more www.ethangardner.com/posts/ai-age...
The Hidden Quality Risks in AI-Agentic Development
Agentic workflows can hide the cost/quality trade-off rather than remove it, making defects harder to trace back to their source.
www.ethangardner.com
July 8, 2026 at 7:21 PM
I don't know if this article will resonate or not, but I felt it necessary to write. I explore the risks of AI software development, defects, and the challenges of building a mental model when the agent does more and more www.ethangardner.com/posts/ai-age...
Reposted by Ethan Gardner
The first part of Declarative Partial Updates (`` out-of-order HTML) is now available, unflagged, in Chrome 150!!
developer.chrome.com/release-note...
The second part (the new JS setting APIs, include the streaming ones) we're still working on the spec side, but maybe for Chrome 152?
developer.chrome.com/release-note...
The second part (the new JS setting APIs, include the streaming ones) we're still working on the spec side, but maybe for Chrome 152?
Chrome 150 | Release notes | Chrome for Developers
CSS text-fit property, background-clip border-area, Focusgroup, and more.
developer.chrome.com
July 2, 2026 at 11:55 AM
The first part of Declarative Partial Updates (`` out-of-order HTML) is now available, unflagged, in Chrome 150!!
developer.chrome.com/release-note...
The second part (the new JS setting APIs, include the streaming ones) we're still working on the spec side, but maybe for Chrome 152?
developer.chrome.com/release-note...
The second part (the new JS setting APIs, include the streaming ones) we're still working on the spec side, but maybe for Chrome 152?
Reposted by Ethan Gardner
The Chrome DevTools team are doing a "papercuts" sprint where they try to address lots of small, irritating bugs and annoyances.
Reply with crbug.com links (no bug, no fix—that's the deal!) and will see what we can do.
No promises though as some may be features/too big/unclear how to solve.
Reply with crbug.com links (no bug, no fix—that's the deal!) and will see what we can do.
No promises though as some may be features/too big/unclear how to solve.
Chromium
crbug.com
June 19, 2026 at 2:40 PM
The Chrome DevTools team are doing a "papercuts" sprint where they try to address lots of small, irritating bugs and annoyances.
Reply with crbug.com links (no bug, no fix—that's the deal!) and will see what we can do.
No promises though as some may be features/too big/unclear how to solve.
Reply with crbug.com links (no bug, no fix—that's the deal!) and will see what we can do.
No promises though as some may be features/too big/unclear how to solve.
My presentation, Making Performance Allies from @perfnow.nl just got posted to YouTube - www.youtube.com/watch?v=ygdx....
The tips I share in the presentation were designed to make #webperf stick beyond the occasional task that finds its way out of the backlog. Enjoy!
The tips I share in the presentation were designed to make #webperf stick beyond the occasional task that finds its way out of the backlog. Enjoy!
Making Performance Allies - Ethan Gardner - performance.now() 2025
YouTube video by Web Conferences Amsterdam
www.youtube.com
June 17, 2026 at 11:51 PM
My presentation, Making Performance Allies from @perfnow.nl just got posted to YouTube - www.youtube.com/watch?v=ygdx....
The tips I share in the presentation were designed to make #webperf stick beyond the occasional task that finds its way out of the backlog. Enjoy!
The tips I share in the presentation were designed to make #webperf stick beyond the occasional task that finds its way out of the backlog. Enjoy!
Reposted by Ethan Gardner
Our favourite conference of the year is back: CSS Day ✨
CSS legends, browser engineers, and web platform experts sharing talks on modern CSS, accessibility, design systems, browser internals, and much more.
cssday.nl
See you next week in Amsterdam? ☕️
CSS legends, browser engineers, and web platform experts sharing talks on modern CSS, accessibility, design systems, browser internals, and much more.
cssday.nl
See you next week in Amsterdam? ☕️
CSS Day 2026, 11th & 12th of June, Amsterdam
CSS Day is the conference for CSS designers, developers, spec writers, and browser vendors.
cssday.nl
June 2, 2026 at 4:22 PM
Our favourite conference of the year is back: CSS Day ✨
CSS legends, browser engineers, and web platform experts sharing talks on modern CSS, accessibility, design systems, browser internals, and much more.
cssday.nl
See you next week in Amsterdam? ☕️
CSS legends, browser engineers, and web platform experts sharing talks on modern CSS, accessibility, design systems, browser internals, and much more.
cssday.nl
See you next week in Amsterdam? ☕️
I did a 10-minute DevTools audit of a top 10k site with real RUM tooling installed. Every Core Web Vitals metric: poor.
The hero image isn't preloaded. The tag manager, consent tool, and coupon service are. Organizational influence showed up in the preloads. www.ethangardner.com/posts/lightn...
The hero image isn't preloaded. The tag manager, consent tool, and coupon service are. Organizational influence showed up in the preloads. www.ethangardner.com/posts/lightn...
What 10 Minutes Revealed About Web Performance and Organizational Priorities
A 10-minute DevTools audit of a top 10k website reveals heavy pages, poor Core Web Vitals, and a preload list that reads like competing team priorities
www.ethangardner.com
May 17, 2026 at 10:37 PM
I did a 10-minute DevTools audit of a top 10k site with real RUM tooling installed. Every Core Web Vitals metric: poor.
The hero image isn't preloaded. The tag manager, consent tool, and coupon service are. Organizational influence showed up in the preloads. www.ethangardner.com/posts/lightn...
The hero image isn't preloaded. The tag manager, consent tool, and coupon service are. Organizational influence showed up in the preloads. www.ethangardner.com/posts/lightn...
I'm really excited for this one, especially for design systems where it will shed more light on component performance.
There's a new #webperf measurement API in the works!
Check out this post looking at the work @jason-williams.co.uk and @jdapena.bsky.social have been putting into there Container Timing—available as an origin trail from Chrome 148 (rolling out next week).
developer.chrome.com/blog/contain...
Check out this post looking at the work @jason-williams.co.uk and @jdapena.bsky.social have been putting into there Container Timing—available as an origin trail from Chrome 148 (rolling out next week).
developer.chrome.com/blog/contain...
Container Timing origin trial | Blog | Chrome for Developers
Try out the Container Timing performance measurement API in origin trial from Chrome 148
developer.chrome.com
May 1, 2026 at 6:55 PM
I'm really excited for this one, especially for design systems where it will shed more light on component performance.
Reposted by Ethan Gardner
In response to our objection to the Prompt API, some folks replied "well, fix it. Propose something better". This is something we end up doing a lot at Firefox…
May 1, 2026 at 9:32 AM
In response to our objection to the Prompt API, some folks replied "well, fix it. Propose something better". This is something we end up doing a lot at Firefox…
Reposted by Ethan Gardner
It's almost time to implement the Soft Navigations API to accurately measure Core Web Vitals for SPAs (React, Vue, Angular, etc.).
We applied your feedback to build the expected final shape. Conduct a final test during the origin trial in Chrome 147-149 → goo.gle/4ttf9eP
We applied your feedback to build the expected final shape. Conduct a final test during the origin trial in Chrome 147-149 → goo.gle/4ttf9eP
April 30, 2026 at 4:08 PM
It's almost time to implement the Soft Navigations API to accurately measure Core Web Vitals for SPAs (React, Vue, Angular, etc.).
We applied your feedback to build the expected final shape. Conduct a final test during the origin trial in Chrome 147-149 → goo.gle/4ttf9eP
We applied your feedback to build the expected final shape. Conduct a final test during the origin trial in Chrome 147-149 → goo.gle/4ttf9eP
Reposted by Ethan Gardner
Layout shifts often only happen at specific screen sizes or after a user interaction.
That's why I built a new free tool: the CLS checker tests your site at 5 different viewport sizes and scrolls down the page.
Try it out here: www.debugbear.com/test/cls
That's why I built a new free tool: the CLS checker tests your site at 5 different viewport sizes and scrolls down the page.
Try it out here: www.debugbear.com/test/cls
April 21, 2026 at 9:10 AM
Layout shifts often only happen at specific screen sizes or after a user interaction.
That's why I built a new free tool: the CLS checker tests your site at 5 different viewport sizes and scrolls down the page.
Try it out here: www.debugbear.com/test/cls
That's why I built a new free tool: the CLS checker tests your site at 5 different viewport sizes and scrolls down the page.
Try it out here: www.debugbear.com/test/cls
Reposted by Ethan Gardner
I'm very excited about this! Have seen some really significant impact in our tests. With the sizes of websites and JS payloads continuing to increase, this is both important and impactful.
Today, we’re excited to give you a sneak peek of our support for shared compression dictionaries, show you how it improves page load times, and reveal when you’ll be able to try the beta yourself. https://cfl.re/42egXfC
Shared Dictionaries: compression that keeps up with the agentic web
Today, we’re excited to give you a sneak peek of our support for shared compression dictionaries, show you how it improves page load times, and reveal when you’ll be able to try the beta yourself.
blog.cloudflare.com
April 17, 2026 at 4:54 PM
I'm very excited about this! Have seen some really significant impact in our tests. With the sizes of websites and JS payloads continuing to increase, this is both important and impactful.
I recently analyzed data from the HTTP Archive to see how the web has changed since the launch and adoption of AI tools. The results show a clear trend. The web is getting heavier at an accelerated rate.
www.ethangardner.com/posts/object...
www.ethangardner.com/posts/object...
An Objective Analysis of AI's Impact on Page Weight
What has happened with page weight with the adoption of AI?
www.ethangardner.com
April 17, 2026 at 1:31 AM
I recently analyzed data from the HTTP Archive to see how the web has changed since the launch and adoption of AI tools. The results show a clear trend. The web is getting heavier at an accelerated rate.
www.ethangardner.com/posts/object...
www.ethangardner.com/posts/object...
Performance isn’t just about the first click; it’s about the entire journey. By making sure your pages are eligible for bfcache, you remove the technical hurdles of the network and CPU, creating a browsing experience that feels as fast as a native app.
www.ethangardner.com/posts/bfcach...
www.ethangardner.com/posts/bfcach...
Back/Forward Cache Demo and Debugging
Using bfcache to plug holes in your site's conversion funnel.
www.ethangardner.com
April 7, 2026 at 3:01 AM
Performance isn’t just about the first click; it’s about the entire journey. By making sure your pages are eligible for bfcache, you remove the technical hurdles of the network and CPU, creating a browsing experience that feels as fast as a native app.
www.ethangardner.com/posts/bfcach...
www.ethangardner.com/posts/bfcach...
I'm listening to an audio book and the author said that he encountered software with more bugs than the Amazon, and I am totally stealing that expression.
April 4, 2026 at 1:24 AM
I'm listening to an audio book and the author said that he encountered software with more bugs than the Amazon, and I am totally stealing that expression.
Reposted by Ethan Gardner
🎨 I gotta say, my latest is a little treasure trove: what even is `contain`?! csswizardry.com/2026/04/what...
What Is CSS Containment and How Can I Use It? – CSS Wizardry
CSS containment lets you isolate layout and paint work to self-contained ‘islands’. Here’s what each contain value does and how to use it safely.
csswizardry.com
April 2, 2026 at 1:41 PM
🎨 I gotta say, my latest is a little treasure trove: what even is `contain`?! csswizardry.com/2026/04/what...
Reposted by Ethan Gardner
⚡WebPerformance Report is more than a report in your inbox.
Users also get access to their Board to manage reports, review deliveries, and follow Performance, Accessibility, and Security trends over time.
Get your report here: 👉https://webperformancereport.com/
#webperf
Users also get access to their Board to manage reports, review deliveries, and follow Performance, Accessibility, and Security trends over time.
Get your report here: 👉https://webperformancereport.com/
#webperf
March 26, 2026 at 7:49 PM
⚡WebPerformance Report is more than a report in your inbox.
Users also get access to their Board to manage reports, review deliveries, and follow Performance, Accessibility, and Security trends over time.
Get your report here: 👉https://webperformancereport.com/
#webperf
Users also get access to their Board to manage reports, review deliveries, and follow Performance, Accessibility, and Security trends over time.
Get your report here: 👉https://webperformancereport.com/
#webperf
Reposted by Ethan Gardner
p75 and p90 JavaScript bytes on the web have exploded since May, 2025—easily the largest 10 month period based on HTTP Archive data since 2023.
The long-tail is getting worse, very quickly.
Gemini, what happened in May 2025?
The long-tail is getting worse, very quickly.
Gemini, what happened in May 2025?
March 26, 2026 at 3:43 PM
p75 and p90 JavaScript bytes on the web have exploded since May, 2025—easily the largest 10 month period based on HTTP Archive data since 2023.
The long-tail is getting worse, very quickly.
Gemini, what happened in May 2025?
The long-tail is getting worse, very quickly.
Gemini, what happened in May 2025?
Reposted by Ethan Gardner
⚡Featured posts this week:
✨ Telescope Test Agent: Mike Kozicki @nywebperf.com
✨ Agentic SEO for e-commerce: Emilie Wilhelm
✨ The Hidden Costs Behind Modern Frontend: Juntao Qiu
✨ Web Performance Archetypes: @ethangardner.com rdner
🙏 Special thanks to the authors!
#webperf
✨ Telescope Test Agent: Mike Kozicki @nywebperf.com
✨ Agentic SEO for e-commerce: Emilie Wilhelm
✨ The Hidden Costs Behind Modern Frontend: Juntao Qiu
✨ Web Performance Archetypes: @ethangardner.com rdner
🙏 Special thanks to the authors!
#webperf
March 22, 2026 at 1:04 PM
⚡Featured posts this week:
✨ Telescope Test Agent: Mike Kozicki @nywebperf.com
✨ Agentic SEO for e-commerce: Emilie Wilhelm
✨ The Hidden Costs Behind Modern Frontend: Juntao Qiu
✨ Web Performance Archetypes: @ethangardner.com rdner
🙏 Special thanks to the authors!
#webperf
✨ Telescope Test Agent: Mike Kozicki @nywebperf.com
✨ Agentic SEO for e-commerce: Emilie Wilhelm
✨ The Hidden Costs Behind Modern Frontend: Juntao Qiu
✨ Web Performance Archetypes: @ethangardner.com rdner
🙏 Special thanks to the authors!
#webperf
Reposted by Ethan Gardner
✨ Core Web Vitals Summit: The Videos ✨
I'll be sharing the recorded sessions from the Summit stream, and some brief commentary on some takeaways and significance. All are welcome to join the conversation!
📆 Monday March 23rd
⏰ 1pm EST, 10am PST
🔗 www.youtube.com/live/LXYcknO...
I'll be sharing the recorded sessions from the Summit stream, and some brief commentary on some takeaways and significance. All are welcome to join the conversation!
📆 Monday March 23rd
⏰ 1pm EST, 10am PST
🔗 www.youtube.com/live/LXYcknO...
March 20, 2026 at 7:46 PM
✨ Core Web Vitals Summit: The Videos ✨
I'll be sharing the recorded sessions from the Summit stream, and some brief commentary on some takeaways and significance. All are welcome to join the conversation!
📆 Monday March 23rd
⏰ 1pm EST, 10am PST
🔗 www.youtube.com/live/LXYcknO...
I'll be sharing the recorded sessions from the Summit stream, and some brief commentary on some takeaways and significance. All are welcome to join the conversation!
📆 Monday March 23rd
⏰ 1pm EST, 10am PST
🔗 www.youtube.com/live/LXYcknO...
Reposted by Ethan Gardner
Is it really possible to anticipate shifts in RUM data from immediate LAB results, using machine learning (ML)? We're going to find out with @ethangardner.com. Joins us for that conversation
✨ SPDY STREAM 027 ✨
📆 Tomorrow, Wednesday March 18th
⏰ 1pm EST, 10am PST
🔗 www.youtube.com/live/ZEy0lRq...
✨ SPDY STREAM 027 ✨
📆 Tomorrow, Wednesday March 18th
⏰ 1pm EST, 10am PST
🔗 www.youtube.com/live/ZEy0lRq...
March 17, 2026 at 11:56 AM
Is it really possible to anticipate shifts in RUM data from immediate LAB results, using machine learning (ML)? We're going to find out with @ethangardner.com. Joins us for that conversation
✨ SPDY STREAM 027 ✨
📆 Tomorrow, Wednesday March 18th
⏰ 1pm EST, 10am PST
🔗 www.youtube.com/live/ZEy0lRq...
✨ SPDY STREAM 027 ✨
📆 Tomorrow, Wednesday March 18th
⏰ 1pm EST, 10am PST
🔗 www.youtube.com/live/ZEy0lRq...
Reposted by Ethan Gardner
Your website has a UX Score and you've probably never seen it.
It's based on real Chrome user data from real visits. Not a lab test. Not a guess.
Enter any URL, get your score in 10 seconds: www.iron-out.io/benchmark
Free. No login 🚀
It's based on real Chrome user data from real visits. Not a lab test. Not a guess.
Enter any URL, get your score in 10 seconds: www.iron-out.io/benchmark
Free. No login 🚀
Free UX Score Check — Website Performance Benchmark
Check your UX Score for free. Real CrUX data across LCP, INP, CLS, TTFB and FCP. Benchmark against the top 300 Dutch websites. No login required.
www.iron-out.io
March 16, 2026 at 11:58 AM
Your website has a UX Score and you've probably never seen it.
It's based on real Chrome user data from real visits. Not a lab test. Not a guess.
Enter any URL, get your score in 10 seconds: www.iron-out.io/benchmark
Free. No login 🚀
It's based on real Chrome user data from real visits. Not a lab test. Not a guess.
Enter any URL, get your score in 10 seconds: www.iron-out.io/benchmark
Free. No login 🚀