Share url in facebook messenger from web

This is what you are looking for:

Link:

<a href=”fb-messenger://share/?link= https%3A%2F%2Fdevelopers.facebook.com%2Fdocs%2Fsharing%2Freference%2Fsend-dialog&app_id=123456789”>Send In Messenger</a>

JavaScript:

window.open('fb-messenger://share?link=' + encodeURIComponent(link) + '&app_id=' + encodeURIComponent(app_id));

Please note that it works only on mobile. For more information see here:

https://developers.facebook.com/docs/sharing/messenger/web

You can use the Send Dialog, which is not supported on mobile: https://developers.facebook.com/docs/sharing/reference/send-dialog#examples

Alternative for mobile: https://developers.facebook.com/docs/sharing/messenger

<a href="fb-messenger://share/?link=http://url-you-want-to-share.com&app_id=your-app-id-here">
... 
</a>

Does not seem to work on desktop, but I could be wrong.

Source: https://developers.facebook.com/docs/sharing/messenger