Hi Mike,
Thank you for pointing out the OT extension limit. Similar to the
Writer API, I have updated the Chromestatus page to reflect OT
extension by 3 milestones.
Please see comments on the progress below.
* Draft spec (early draft is ok, but must be spec-like and
associated with the appropriate standardization venue, or WICG)
o The shared Writing Assistance APIs draft spec
<https://webmachinelearning.github.io/writing-assistance-apis/> is
relatively comprehensive and has already supported the launch
of the Summarizer API, plus Shared Infrastructure
<https://webmachinelearning.github.io/writing-assistance-apis/#supporting>
already
leveraged
<https://webmachinelearning.github.io/translation-api> for
Translator
<https://chromestatus.com/feature/5172811302961152> and
LanguageDetector
<https://chromestatus.com/feature/6494349985841152> launches.
Reilly Grant has stepped up to take on Editor duties for this
spec through its incubation in the Web Machine Learning
Community Group.
* TAG review (see exceptions)
o The Writing Assistance APIs
<https://github.com/w3ctag/design-reviews/issues/991> TAG
review intentionally timed
<https://github.com/w3ctag/design-reviews/issues/991#issuecomment-3166120120>
out
to focus review efforts on the in-progress Prompt API
<https://github.com/w3ctag/design-reviews/issues/1093> TAG
review request. Since these APIs share much infrastructure, we
look forward to receiving thoughtful and broad TAG design
feedback.
* signals requests
o These APIs are being discussed within the WebML CG which has
participation from other browser vendors and Microsoft intends
to follow our lead on launching these APIs using their own
models.
* Outreach for feedback from the spec community
o Chrome's
https://github.com/webmachinelearning/writing-assistance-apis/issues/33
* WPT tests
o We've explained significant progress on Writer and Rewriter
WPT coverage in the original message. While not fully covered:
"The API surface is reasonably well tested with mocked models,
but production model downloading and non-deterministic outputs
are not fully tested at the web-platform-tests layer. The
explainer discusses this in
https://github.com/WICG/writing-assistance-apis/blob/main/README.md#specifications-and-tests
<https://github.com/WICG/writing-assistance-apis/blob/main/README.md#specifications-and-tests>."
Thanks,
Deepti
On Tue, Oct 28, 2025 at 11:25 AM Mike Taylor <[email protected]>
wrote:
Similar to the Writer API, this can only be extended for 3 months.
See similar questions on progress below, thanks.
On 10/28/25 11:40 a.m., Deepti Bogadi wrote:
Gentle reminder to review the Intent to Extend Experimentation
for the Rewriter API. Let me know if you have any questions.
Thanks,
Deepti
On Wed, Oct 22, 2025 at 11:18 AM Deepti Bogadi
<[email protected]> wrote:
Contact emails
[email protected], [email protected],[email protected]
Explainer
https://github.com/explainers-by-googlers/writing-assistance-apis/blob/main/README.md
<https://github.com/explainers-by-googlers/writing-assistance-apis/blob/main/README.md>
Specification
https://webmachinelearning.github.io/writing-assistance-apis/#rewriter-api
<https://webmachinelearning.github.io/writing-assistance-apis/#rewriter-api>
Summary
The Rewriter API transforms and rephrases input text in
requested ways, backed by an on-device AI language model.
Developers may use this API to remove redundancies within a
text in order to fit into a word limit, rephrase messages to
suit the intended audience or to be more constructive if a
message is found to use toxic language, rephrasing a post or
article to use simpler words and concepts and more. An
enterprise policy (GenAILocalFoundationalModelSettings) is
available to disable the underlying model downloading which
will render the API unavailable.
Blink component
Blink > AI > Writing Assistance
<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%20%3E%20AI%20%3E%20Writing%20Assistance%22>
Web Feature ID
No information provided
TAG review
https://github.com/w3ctag/design-reviews/issues/991
<https://github.com/w3ctag/design-reviews/issues/991>
TAG review status
Pending
Origin Trial Name
Rewriter API
Chromium Trial Name
AIRewriterAPI
Origin Trial documentation link
https://github.com/webmachinelearning/writing-assistance-apis/blob/main/README.md#rewriter-api
WebFeature UseCounter name
Rewriter_Create
Risks
Interoperability and Compatibility
This feature has definite interoperability and compatibility
risks, due to the likelihood that different implementations
will use different language models, prompts, and
fine-tunings, and even within a single implementation such as
Chrome, these pieces will likely change over time.
Additionally, not all browsers and operating systems will
have a built-in language model to expose, and not all devices
will be powerful enough to run one effectively. We are taking
a variety of steps to attempt to mitigate these risks. For
example, the specification is designed to allow the API to be
backed by a cloud-based language model. This approach could
extend the functionality to a wider range of devices and
users. The API is designed to abstract away the specifics of
the underlying language model, including prompts and
fine-tuning. This prevents developers from relying on
specific outputs, ensuring they receive rewritten text rather
than structured data that might vary across implementations.
Finally, the API surface is designed with many clear points
of failure, that encourage the developer to probe for
capabilities ahead of time and fall back to other techniques
if a capability is not available. Nevertheless,
interoperability and compatibility risk remains high for
these sorts of APIs, and we'll be closely monitoring it
during the experiment period.
Gecko: Negative
(https://github.com/mozilla/standards-positions/issues/1067
<https://github.com/mozilla/standards-positions/issues/1067>)
WebKit: No signal
(https://github.com/WebKit/standards-positions/issues/393
<https://github.com/WebKit/standards-positions/issues/393>)
Web developers: Mixed signals
(https://github.com/WICG/proposals/issues/163
<https://github.com/WICG/proposals/issues/163>) Prototyping
with partners behind a flag revealed enthusiasm and many
prototypes built, from which we drew the discussion of
potential use cases [1]. Feedback on the WICG thread was more
mixed. Some themes we saw include: asking for more
capabilities (e.g. full prompting of a language model instead
of higher-level APIs (our response at [2]); multi-modal
support); desire to make sure the API actually works robustly
in many real-world use cases; removal of any safety/ethical
safeguards; and confusion about client-side vs. cloud APIs.
[1]:
https://github.com/WICG/writing-assistance-apis/blob/main/README.md#summarizer-api
<https://github.com/WICG/writing-assistance-apis/blob/main/README.md#summarizer-api>[2]:
https://github.com/WICG/writing-assistance-apis/blob/main/README.md#directly-exposing-a-prompt-api
<https://github.com/WICG/writing-assistance-apis/blob/main/README.md#directly-exposing-a-prompt-api>
Other signals:
Activation
This feature would definitely benefit from having polyfills,
backed by any of: cloud services, lazily-loaded client-side
models using WebGPU, or the web developer's own server. We
anticipate seeing an ecosystem of such polyfills grow as more
developers experiment with this API.
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
Goals for experimentation
Although developers have prototyped using the behind-a-flag
implementation and given good feedback, several partners are
interested in testing out the API with real users. We're
looking forward to getting feedback from such testing,
especially with regards to output quality, multilingual
support, and what types of input data are handled well vs.
poorly. We also want to understand whether we've found the
right set of options to offer to control the output, and
whether the resulting output reflects those controls to the
extent that developers expect.
Reason this experiment is being extended
Rewriter API suffers from perceived quality issues and a
critical language support disconnect. These APIs are
currently not production-ready for many use cases,
particularly those outside of English. In addition, we are
also seeing low adoption in the OT phase for this API. Hence,
we are requesting the extension of the trial to give us time
to collect more feedback from our partners and make the API
more robust and resilient.
Can you please comment on progress in these areas, per
https://www.chromium.org/blink/launching-features/#origin-trials?
Draft spec (early draft is ok, but must be spec-like and
associated with the appropriate standardization venue, or WICG)
TAG review (see exceptions)
signals requests
Outreach for feedback from the spec community
WPT tests
Ongoing technical constraints
As discussed above, not all devices are capable of running
the language models required to implement this API. The
availability() function allows developers to feature-detect
whether the current device can support the API.
Debuggability
It is possible that giving DevTools more insight into the
nondeterministic states of the model, e.g. random seeds,
could help with debugging. See related discussion at
https://github.com/explainers-by-googlers/prompt-api/issues/9
<https://github.com/explainers-by-googlers/prompt-api/issues/9>.
Will this feature be supported on all six Blink platforms
(Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?
No
Not all platforms will come with a language model. In
particular, in the initial stages we are focusing on Windows,
Mac, and Linux.
Is this feature fully tested by web-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?
No
The API surface is reasonably well tested with mocked models,
but production model downloading and non-deterministic
outputs are not fully tested at the web-platform-tests layer.
The explainer discusses this in
https://github.com/WICG/writing-assistance-apis/blob/main/README.md#specifications-and-tests
<https://github.com/WICG/writing-assistance-apis/blob/main/README.md#specifications-and-tests>.
DevTrial instructions
https://docs.google.com/document/d/1v6-fOC13zS3S-bOLuqIRbzgmia_aPGJl-wzOx4ItSVE/edit?usp=sharing
<https://docs.google.com/document/d/1v6-fOC13zS3S-bOLuqIRbzgmia_aPGJl-wzOx4ItSVE/edit?usp=sharing>
Flag name on about://flags
rewriter-api-for-gemini-nano
Finch feature name
AIRewriterAPI
Requires code in //chrome?
True
Tracking bug
https://issues.chromium.org/issues/358214322
<https://issues.chromium.org/issues/358214322>
Launch bug
https://launch.corp.google.com/launch/4396842
<https://launch.corp.google.com/launch/4396842>
Non-OSS dependencies
Does the feature depend on any code or APIs outside the
Chromium open source repository and its open-source
dependencies to function?
Yes: this feature depends on a language model, which is
bridged to the open-source parts of the implementation via
the interfaces in //services/on_device_model.
Estimated milestones
Origin trial desktop first
137
Origin trial desktop last
142
Origin trial extension 1 end milestone
148
DevTrial on desktop
129
Anticipated spec changes
Open questions about a feature may be a source of future web
compat or interop issues. Please list open issues (e.g. links
to known github issues in the project for the feature
specification) whose resolution may introduce web
compat/interop risk (e.g., changing to naming or structure of
the API in a non-backward-compatible way).
At this point all known proposed changes have been
incorporated into the specification and implementation.
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5112320150470656?gate=5133588907556864
<https://chromestatus.com/feature/5112320150470656?gate=5133588907556864>
Links to previous Intent discussions
Intent to Prototype:
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra9Jhe7o59mX5tJPD%3DcZQb2oL3mNi-T57wA86fPXn55OPw%40mail.gmail.com
<https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra9Jhe7o59mX5tJPD%3DcZQb2oL3mNi-T57wA86fPXn55OPw%40mail.gmail.com>
Intent to Experiment:
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra8dnNHXKM26MvQxZ6LBE16PUbvH6-GH5B3Z2WDv4uH0WQ%40mail.gmail.com
<https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra8dnNHXKM26MvQxZ6LBE16PUbvH6-GH5B3Z2WDv4uH0WQ%40mail.gmail.com>
This intent message was generated by Chrome Platform Status
<https://chromestatus.com/>.
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