Intent to Prototype: Origin Private File System extension: AccessHandle

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Emanuel Krivoy

Aug 4, 2021, 11:49:59 AM8/4/21
to blink-dev, Domenic Denicola,, Thomas Steiner, Emanuel Ziegler

Contact emails




The Origin Private File System (OPFS, part of the File System Access API) is augmented with a new surface that brings very performant access to data. This new surface differs from existing ones by offering in-place and exclusive write access to a file’s content. This change, along with the ability to consistently read unflushed modifications and the availability of a synchronous variant on dedicated workers, significantly improves performance and unblocks new use cases.

Blink component



Our goal is to give developers flexibility by providing generic, simple, and performant primitives upon which they can build higher-level storage components. The new surface is particularly well suited for Wasm-based libraries and applications that want to use custom storage algorithms to fine-tune execution speed and memory usage.

Initial public proposal

TAG review

TAG review status



Interoperability and Compatibility

Gecko: No signal

WebKit: No signal

Web developers: No signals


Is this feature fully tested by web-platform-tests?


Flag name

Requires code in //chrome?


Tracking bug

Launch bug

Estimated milestones

Link to entry on the Chrome Platform Status

This intent message was generated by Chrome Platform Status.

Mathias Bynens

Aug 5, 2021, 4:58:23 AM8/5/21
to Emanuel Krivoy, blink-dev, Domenic Denicola,, Thomas Steiner, Emanuel Ziegler
The Intentemail template includes a “Debuggability” section, which was left empty in this case. How would web developers debug this new functionality through DevTools? See for context.

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Emanuel Krivoy

Aug 6, 2021, 1:53:56 PM8/6/21
to Mathias Bynens, blink-dev, Domenic Denicola,, Thomas Steiner, Emanuel Ziegler
Ah, that section is not exposed in the new chrome status UI, sorry it was missing.

Looking at the checklist, we are covered on basic tooling; Autocomplete works as described in "New WebIDL/DOM interfaces and attributes".

As for extended tooling, we'll eventually want to be able to explore files stored in OPFS. There are two tracking bugs related to this: and This API doesn't really add new storage backends, just new ways to interact with files, so we'd be covered by those as well. 
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