Web Custom formats let websites read and write arbitrary unsanitized payloads using a standardized web custom format, as well as read and write a limited subset of OS-specific formats (for supporting legacy apps). The name of the clipboard format is mangled by the browser in a standardized way to indicate that the content is from the web, which allows native applications to opt-in to accepting the unsanitized content.


Powerful web applications would like to exchange data payloads with web and native applications via the OS clipboard (copy-paste). The existing Web Platform has an API that supports the most popular standardized data types (text, image, rich text) across all platforms. However, this API does not scale to the long tail of specialized formats. In particular, custom formats, non-web-standard formats like TIFF (a large image format), and proprietary formats like .docx (a document format), are not supported by the current Web Platform.



Status in Chromium


In development (tracking bug)

Consensus & Standardization

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


Intent to Prototype url

Intent to Prototype thread

Search tags

pickle, pickling api, pickling, clipboard custom format, Web Custom formats,

Last updated on 2022-03-02