Please add support for parallel API. Albeit having different names, I guess they have the same functionality. On another note: I don't know why there are some incoordination between some userscript managers projects and I'm not sure how this situation should be handled. I think that the project owners of each, including Falkon, Otter and Pale Moon, should establish a public review meeting where they publish decisions and .
Makyen has offered a solution: > In Greasemonkey 4, GM.xmlHttpRequest() is the "new" name for making requests from userscripts which use the elevated permissions available to browser extensions. This allows it to be able to do things which in-page requests can't do. > > For all other userscript managers, including Greasemonkey 3, the name for that function is GM_xmlhttpRequest. The two functions are largely identical across userscript managers, as long as you stick to using the on* properties in the object you pass as the argument. Some userscript managers return a Promise, but not all include valid data in the response passed to .then(). > > So, you can do something like: > > // @grant GM_xmlhttpRequest > // @grant GM.xmlHttpRequest > // ==/UserScript== > const gmXmlhttpRequest = typeof GM_xmlhttpRequest === 'function' ? GM_xmlhttpRequest : GM.xmlHttpRequest; > > You can then use gmXmlhttpRequest and be compatible with all userscript managers of which I'm aware in nearly all circumstances. Source: https://github.com/greasemonkey/greasemonkey/issues/3160#issuecomment-1456758080