That is not really part of firefox help here. But if you did do a search you find there were a couple threads on this already. https://support.mozilla.org/en-US/questions/1126747 https://support.mozilla.org/en-US/questions/1195234

https://support.mozilla.org/en-US/kb/import-bookmarks-data-another-browser Only Internet Explorer, Edge, and Chrome are available for Firefox to "Import bookmarks ''(and maybe other data)'' from another browser" In Opera, look for the option to '''Export bookmarks in html format''' which might be in the '''File''' menu. ''It was located there in the old Presto version of Opera''. Then import that bookmarks.html file into Firefox. https://support.mozilla.org/en-US/kb/import-bookmarks-html-file Importing "other data" just isn't possible. Limits by the "other browsers" not being setup to "export" and with Firefox - as there is no common file storage system for interchange as there is with bookmarks data.