Some systems say a tab is 8 spaces, others say it's 4. Some editors can set a tab to any customizable N spaces. But a space is always a space so your code will look like you intended (or should I say indented) it no matter who's looking at it.
Sure, IDE's are easy (though many people use multiple IDE's and/or editors across multiple machines).
I've also got a couple diff tools, a few VCS's, also the online parts of VCS like web-based pull request review UI's.
Tabs also tend not to play as nice with vertically aligned elements, if you prefer that for things like say the '.' on multi-line chained method calls, or longer function parameter lists.
I'll work without complaint or changing it with any existing code whether spaces or tabs. Mix the two for indentation however and fixing it is the first commit I make before touching anything else.