If you're applying for local jobs, Bulk Apply is one tool that you can use.
LazyApply is well known, although a lot of people say it's spotty.
If you're looking primarily for remote jobs, you should try Jobsolv.
There's also LoopCV, which tends to specialize in academic-related jobs.
But there are a lot of tools out there, and it's all about just entering your resume once and the tools would automatically spawn different versions that would be then passed on to different platforms where people post jobs.
Now with all that said, keep in mind that you need to use platforms that filter the available jobs.
Otherwise, you might just be throwing spaghetti against the wall, and ending up with nothing.