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Large-Allocation

Non-standard
This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The Large-Allocation response header tells the browser that the page being loaded is going to want to perform a large allocation.

WebAssembly or asm.js applications can use large contiguous blocks of allocated memory. For complex games, for example, these allocations can be quite large, sometimes as large as 1GB. The Large-Allocation tells the browser that the web content in the to-be-loaded page is going to want to perform a large contiguous memory allocation and the browser can react to this header by starting a dedicated process for the to-be-loaded document, for example.

Header type	Response header
Forbidden header name	no

Syntax

Large-Allocation: 0
Large-Allocation: <megabytes>

Directives

0: 0 is a special value which represents uncertainty as to what the size of the allocation is.
<megabytes>: The expected size of the allocation to be performed, in megabytes.

Examples

Large-Allocation: 0
Large-Allocation: 500

Specifications

Not part of any current specifications. An explainer of the ideas behind this header can be found in this document.

Browser compatibility

Feature	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Servo
Large-Allocation	No support	No support	No support¹	No support	No support	No support	No support

Feature	Android	Chrome for Android	Edge Mobile	Firefox for Android	IE Mobile	Opera Mobile	Safari Mobile
Large-Allocation	No support	No support	No support	No support	No support	No support	No support