Add information about Chrome DevTools extensibility API

[tunetheweb]

Description

Chrome DevTool's extensibility API extends some standard (and non-standard!) Web APIs with either new additions, or in the use of structured versions of existing fields.

Therefore I think it is helpful for developers who may see these being used in the wild to understand them.

At the same time, as these are non-standard extensions (at least for now!) I don't think it should be documented on MDN other than a small note. I'm also conscious that MDN is not a documentation site for specific browsers, but rather the web platform which is another reason to keep this light. Happy to take feedback on this and iterate if you don't think I've struck the right balance here.

Motivation

A developer approached me confused that the console.timeStamp MDN docs suggested this API did not allow for the extensions Chrome uses.

Additionally, with the likes of popular libraries like React and Angular uses the extensibility API, this is becoming a more popular API.

Firefox have also expressed interest to potentially implementing these extensions (at which point we can document this more on MDN as it's more cross-browser).

Additional details

https://developer.chrome.com/docs/devtools/performance/extension

Related issues and pull requests

[github-actions]

Preview URLs (6 pages)

• /en-US/docs/Web/API/Performance/mark
• /en-US/docs/Web/API/Performance/measure
• /en-US/docs/Web/API/PerformanceMark/PerformanceMark
• /en-US/docs/Web/API/PerformanceMark
• /en-US/docs/Web/API/PerformanceMeasure
• /en-US/docs/Web/API/console/timeStamp_static

External URLs (6)

URL: /en-US/docs/Web/API/console/timeStamp_static
Title: console: timeStamp() static method

• https://developer.chrome.com/docs/devtools/performance/extension (2 times) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/API/Performance/mark
Title: Performance: mark() method

• https://developer.chrome.com/docs/devtools/performance/extension (2 times) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/API/Performance/measure
Title: Performance: measure() method

• https://developer.chrome.com/docs/devtools/performance/extension (2 times) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/API/PerformanceMark
Title: PerformanceMark

• https://developer.chrome.com/docs/devtools/performance/extension (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/API/PerformanceMark/PerformanceMark
Title: PerformanceMark: PerformanceMark() constructor

• https://developer.chrome.com/docs/devtools/performance/extension (2 times) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/API/PerformanceMeasure
Title: PerformanceMeasure

• https://developer.chrome.com/docs/devtools/performance/extension (1 time) (Note! This may be a new URL 👀)

(comment last updated: 2025-10-24 16:33:13)

[tunetheweb]

Thanks @wbamberg . I've now done this the proper way, rather than trying to wedge it in as a note.

[wbamberg]

👍 thank you.

[Penya1313]