LGTM1 On Tue, Nov 25, 2025 at 11:29 AM Thomas Steiner <[email protected]> wrote:
> I have recently suggested sites use this API to download large AI models > in the background <https://web.dev/articles/background-fetch-ai> as a > progressive enhancement (so no breakage). > > > For more advanced use cases, such as providing offline access to large > files, developers can use the Fetch API within a Service Worker to download > and cache the necessary resources. > > It sounds like this is only possible until the UA kills the service > worker, as it's not meant to be kept alive indefinitely, which would be a > requirement for the use case described above. > > > On Tue, Nov 25, 2025 at 9:47 AM Yoav Weiss (@Shopify) < > [email protected]> wrote: > >> What would breakage look like? I agree that usage is very low, but would >> you expect users of those rare sites to be aware of breakage? Or would it >> just prevent those sites from optimizing some flows? >> >> On Tue, Nov 25, 2025 at 5:41 AM Chromestatus < >> [email protected]> wrote: >> >>> *Contact emails* >>> [email protected] >>> >>> *Explainer* >>> *No information provided* >>> >>> *Specification* >>> https://wicg.github.io/background-fetch >>> >>> *Summary* >>> Deprecates the Background Fetch API, which allows web applications to >>> download large files in the background, even if the user navigates away >>> from the page or closes the browser. Despite being available in Chrome >>> since version 74, the Background Fetch API has not seen wide adoption by >>> the developer community, with usage remaining consistently low, at less >>> than 0.00002% of page loads as of November 2025. Given the low adoption >>> rate and the significant engineering effort required to maintain the API >>> and address ongoing security issues, it is being deprecated. Developers are >>> encouraged to explore alternative solutions for managing large file >>> downloads. >>> >>> *Blink component* >>> Blink>ServiceWorker >>> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EServiceWorker%22> >>> >>> *Web Feature ID* >>> background-fetch <https://webstatus.dev/features/background-fetch> >>> >>> *Motivation* >>> The Background Fetch API has been available in Chrome since version 74. >>> However, it has not seen wide adoption. Usage metrics show that the feature >>> is used in less than 0.00002% of page loads as of November 2025. Given the >>> low usage, the ongoing engineering effort to maintain the Background Fetch >>> API and address security issues is no longer justifiable. For developers >>> who need to provide users with the ability to download large files, there >>> are several alternatives: - For simple file downloads, developers can >>> provide a standard download link. - For more advanced use cases, such as >>> providing offline access to large files, developers can use the Fetch API >>> within a Service Worker to download and cache the necessary resources. This >>> approach provides developers with greater control over the user experience. >>> >>> *Initial public proposal* >>> *No information provided* >>> >>> *TAG review* >>> *No information provided* >>> >>> *TAG review status* >>> Not applicable >>> >>> *Risks* >>> >>> >>> *Interoperability and Compatibility* >>> The interoperability risk of removing the Background Fetch API is low. >>> The API has not been implemented by Firefox or Safari, and there have been >>> no signals from either to indicate that they intend to do so. As a result, >>> removing this API from Chrome will not cause interoperability issues, as it >>> is not a feature that is part of the interoperable web platform. The >>> compatibility risk is also minimal. Usage of the Background Fetch API has >>> remained consistently low, at less than 0.00002% of page loads as of >>> November 2025. Because of this extremely low usage, the number of websites >>> that will be affected by this removal is very small. >>> >>> *Gecko*: No signal ( >>> https://github.com/mozilla/standards-positions/issues/30) >>> >>> *WebKit*: No signal ( >>> https://github.com/WebKit/standards-positions/issues/149) >>> >>> *Web developers*: No signals >>> >>> *Other signals*: TAG: >>> https://github.com/w3ctag/design-reviews/issues/279 >>> >>> *Ergonomics* >>> The Background Fetch API is tightly coupled with the Service Worker API. >>> It is accessed through the backgroundFetch property of a >>> ServiceWorkerRegistration object. Developers using this API would also >>> likely use the Fetch API to create the Request objects for the download and >>> the Cache API to store the downloaded responses. The API is designed to be >>> asynchronous and to operate in the background. The main fetch() method >>> returns a Promise, and the download process is managed by the browser, off >>> the main thread. This design avoids blocking the main thread and is >>> intended to improve performance and battery life for large downloads >>> compared to keeping a service worker alive for a long-running fetch. >>> Therefore, the API's usage does not inherently pose a performance risk that >>> would make it difficult for Chrome to maintain good performance. The >>> deprecation is due to low adoption and high maintenance cost, not because >>> of ergonomic or performance issues in its design. >>> >>> *Activation* >>> This change is a deprecation and removal of an existing API. The primary >>> risk is the impact on developers who are currently using the Background >>> Fetch API. However, the "activation" risk for this removal is minimal. The >>> API has seen extremely low adoption since its introduction in Chrome 74, >>> with usage below 0.00002% of page loads. This indicates that very few >>> developers will be required to take action. >>> >>> *Security* >>> The removal of the Background Fetch API reduces the overall attack >>> surface of the browser and mitigates existing security issues associated >>> with maintaining the feature. >>> >>> *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 >>> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?* >>> No >>> >>> >>> *Flag name on about://flags* >>> *No information provided* >>> >>> *Finch feature name* >>> BackgroundFetch >>> >>> *Rollout plan* >>> Will ship enabled for all users >>> >>> *Requires code in //chrome?* >>> False >>> >>> *Tracking bug* >>> https://crbug.com/460293588 >>> >>> *Estimated milestones* >>> Shipping on desktop 146 >>> Shipping on Android 146 >>> Shipping on WebView 146 >>> >>> *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). >>> *No information provided* >>> >>> *Link to entry on the Chrome Platform Status* >>> https://chromestatus.com/feature/5074579353632768?gate=6606728540061696 >>> >>> This intent message was generated by Chrome Platform Status >>> <https://chromestatus.com>. >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "blink-dev" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion visit >>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6925253c.050a0220.107b62.0899.GAE%40google.com >>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6925253c.050a0220.107b62.0899.GAE%40google.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "blink-dev" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion visit >> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohS%2Bcs0k2mxNHSZse%2BGdB8Z9Ei8%2BADkaLh-fxRe%3DoJqWLMw%40mail.gmail.com >> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohS%2Bcs0k2mxNHSZse%2BGdB8Z9Ei8%2BADkaLh-fxRe%3DoJqWLMw%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > > > -- > Thomas Steiner, PhD—Developer Relations Engineer (blog.tomayac.com, > toot.cafe/@tomayac) > > Google Spain, S.L.U. > Torre Picasso, Pl. Pablo Ruiz Picasso, 1, Tetuán, 28020 Madrid, Spain > > CIF: B63272603 > Inscrita en el Registro Mercantil de Madrid, sección 8, Hoja M-435397 > Tomo 24227 Folio 25 > > ----- BEGIN PGP SIGNATURE ----- > Version: GnuPG v2.4.8 (GNU/Linux) > > iFy0uwAntT0bE3xtRa5AfeCheCkthAtTh3reSabiGbl0ck > 0fjumBl3DCharaCTersAttH3b0ttom.xKcd.cOm/1181. > ----- END PGP SIGNATURE ----- > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohSL-irikrJT1hgoW73H5FmGj3eNu3MvcqcEOMnwO7Zfk6g%40mail.gmail.com.
