Ready for Developer Testing: Incremental font transfer

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Will Medrano

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Apr 15, 2026, 8:00:24 PM (2 days ago) Apr 15
to spec-mentors
Contact emails
wmed...@google.com, wmed...@chromium.org, gri...@google.com

Explainer
https://garretrieger.github.io/ift-demo

Specification
https://www.w3.org/TR/IFT

Summary
Incremental font transfer enables the browser to download only the specific portions of a web font needed to render the text currently visible on a page. This reduces bandwidth usage and improves page load times for sites using large fonts. This allows developers to optimize web performance without needing to manually generate and manage font subsets.

Blink component
Blink>WebFonts

Web Feature ID
Missing feature

Goals for experimentation
None

Risks


Interoperability and Compatibility
No information provided

Gecko: No signal

WebKit: No signal

Web developers: No signals

Other signals:

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?

No information provided


Debuggability
No information provided

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?
No

Is this feature fully tested by web-platform-tests?
No


Flag name on about://flags
No information provided

Finch feature name
No information provided

Non-finch justification
No information provided

Requires code in //chrome?
False

Tracking bug
https://g-issues.chromium.org/issues/498722796

Estimated milestones

No milestones specified



Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5135917565214720

This intent message was generated by Chrome Platform Status.

Will Medrano

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Apr 15, 2026, 8:04:08 PM (2 days ago) Apr 15
to spec-mentors, Will Medrano
Hey y'all. I was following the instructions on the Chromium feature and it suggested sending this out to spec mentors. Not sure if it was ok to just send it out to blink-dev since this feature already has a W3C entry https://www.w3.org/TR/IFT/

Other alias: wmed...@google.com

On Wednesday, April 15, 2026 at 5:00:24 PM UTC-7 Will Medrano wrote:

David Baron

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Apr 16, 2026, 3:53:04 PM (11 hours ago) Apr 16
to Will Medrano, spec-mentors
Responding as a random member of spec-mentors who noticed that nobody else responded (I suspect others may not have noticed what mailing list this was on.)

Is "Ready for developer testing" the right stage for this?  If I look at the bug, it doesn't link to landed code.  Is the code linked from somewhere else, or did you intend to send an Intent to Prototype rather than a Ready for Developer Testing message?

Also, a few things you should or might change first:
  1. change the issue URL from "g-issues" to "issues" so folks outside Google can access it.
  2. I hope the answer to the "all six blink platforms" question is yes rather than no!  (Maybe update it?)
  3. I hope the answer to the "webview application risks" is that there aren't any because the new feature needs to be explicitly invoked in some way.
  4. This seems like the sort of thing that probably should have web platform tests.  It might be good to expand on or correct the current "No".  (But see question above about the right stage.)
  5. Maybe try to add a little more to the section on signals, either from other implementors or from web developers.
-David

On Wed, Apr 15, 2026 at 8:04 PM Will Medrano <wmed...@chromium.org> wrote:
Hey y'all. I was following the instructions on the Chromium feature and it suggested sending this out to spec mentors. Not sure if it was ok to just send it out to blink-dev since this feature already has a W3C entry https://www.w3.org/TR/IFT/

Other alias: wmed...@google.com

On Wednesday, April 15, 2026 at 5:00:24 PM UTC-7 Will Medrano wrote:

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Will Medrano

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Apr 16, 2026, 3:59:39 PM (11 hours ago) Apr 16
to spec-mentors, David Baron, spec-mentors, Will Medrano
Ooof thanks!

I have to mess around with the UI a bit. "Intent to Prototype" is the correct one! I intend to prototype for all six blink platforms. I'll add more signals and think about "web platform test" stuff

On Thursday, April 16, 2026 at 12:53:04 PM UTC-7 David Baron wrote:
Responding as a random member of spec-mentors who noticed that nobody else responded (I suspect others may not have noticed what mailing list this was on.)

Is "Ready for developer testing" the right stage for this?  If I look at the bug, it doesn't link to landed code.  Is the code linked from somewhere else, or did you intend to send an Intent to Prototype rather than a Ready for Developer Testing message?

Also, a few things you should or might change first:
  1. change the issue URL from "g-issues" to "issues" so folks outside Google can access it.
  2. I hope the answer to the "all six blink platforms" question is yes rather than no!  (Maybe update it?)
  3. I hope the answer to the "webview application risks" is that there aren't any because the new feature needs to be explicitly invoked in some way.
  4. This seems like the sort of thing that probably should have web platform tests.  It might be good to expand on or correct the current "No".  (But see question above about the right stage.)
  5. Maybe try to add a little more to the section on signals, either from other implementors or from web developers.
-David

On Wed, Apr 15, 2026 at 8:04 PM Will Medrano <wmed...@chromium.org> wrote:
Hey y'all. I was following the instructions on the Chromium feature and it suggested sending this out to spec mentors. Not sure if it was ok to just send it out to blink-dev since this feature already has a W3C entry https://www.w3.org/TR/IFT/

Other alias: wmed...@google.com

On Wednesday, April 15, 2026 at 5:00:24 PM UTC-7 Will Medrano wrote:
To unsubscribe from this group and stop receiving emails from it, send an email to spec-mentors+unsubscribe@chromium.org.

David Baron

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Apr 16, 2026, 4:46:16 PM (10 hours ago) Apr 16
to Will Medrano, spec-mentors
Some of these things can be tricky to find in the UI, since they're spread across more than one stage.  If you can't find it by going through the stages, the "Edit all fields" UI also works.

-David

On Thu, Apr 16, 2026 at 3:59 PM Will Medrano <wmed...@chromium.org> wrote:
Ooof thanks!

I have to mess around with the UI a bit. "Intent to Prototype" is the correct one! I intend to prototype for all six blink platforms. I'll add more signals and think about "web platform test" stuff

On Thursday, April 16, 2026 at 12:53:04 PM UTC-7 David Baron wrote:
Responding as a random member of spec-mentors who noticed that nobody else responded (I suspect others may not have noticed what mailing list this was on.)

Is "Ready for developer testing" the right stage for this?  If I look at the bug, it doesn't link to landed code.  Is the code linked from somewhere else, or did you intend to send an Intent to Prototype rather than a Ready for Developer Testing message?

Also, a few things you should or might change first:
  1. change the issue URL from "g-issues" to "issues" so folks outside Google can access it.
  2. I hope the answer to the "all six blink platforms" question is yes rather than no!  (Maybe update it?)
  3. I hope the answer to the "webview application risks" is that there aren't any because the new feature needs to be explicitly invoked in some way.
  4. This seems like the sort of thing that probably should have web platform tests.  It might be good to expand on or correct the current "No".  (But see question above about the right stage.)
  5. Maybe try to add a little more to the section on signals, either from other implementors or from web developers.
-David

On Wed, Apr 15, 2026 at 8:04 PM Will Medrano <wmed...@chromium.org> wrote:
Hey y'all. I was following the instructions on the Chromium feature and it suggested sending this out to spec mentors. Not sure if it was ok to just send it out to blink-dev since this feature already has a W3C entry https://www.w3.org/TR/IFT/

Other alias: wmed...@google.com

On Wednesday, April 15, 2026 at 5:00:24 PM UTC-7 Will Medrano wrote:
To unsubscribe from this group and stop receiving emails from it, send an email to spec-mentors...@chromium.org.
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