Provides a new approach to load a large number of resources efficiently using a format that allows multiple resources to be bundled, e.g. Web Bundles.


Loading many unbundled resources is still slower in 2020. We concluded that bundling was necessary in 2018, and our latest local measurement still suggests that. The output of JS bundlers (e.g. webpack) doesn't interact well with the HTTP cache. They are pretty good tools but configuring them to work in an optimal way is tough, and sometimes they'are also incompatible with new requirements like dynamic bundling (e.g. small edit with tree shaking could invalidate everything). With JS bundlers, execution needs to wait for the full bytes to come. Ideally loading multiple subresources should be able to utilize full streaming and parallelization, but that's not possible if all resources are bundled as one javascript. (For JS modules execution still needs to be waited for the entire tree due to the current deterministic execution model)


Status in Chromium


Origin trial (tracking bug)

Consensus & Standardization

After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.

  • No signal
  • No signal
  • No signals


Intent to Prototype url

Intent to Prototype thread

Last updated on 2022-04-13