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.

Returns the build identifier of the browser. In modern browsers this property now returns a fixed timestamp as a privacy measure, e.g. 20181001000000 in Firefox 64 onwards.


A string representing the build identifier of the application. The build ID is in the form YYYYMMDDHHMMSS.




Not part of any public standard.

Browser compatibility

BCD tables only load in the browser