I think square brackets are available in all (?) keyboard layouts, but they may not have dedicated keys. On the Swedish layout, for example, [] are typed using

I think square brackets are available in all (?) keyboard layouts, but they may not have dedicated keys. On the Swedish layout, for example, [] are typed using Alt Gr (i.e. right alt) + 8/9. I know a few developers who use an English keyboard layout when programming, just to avoid contorting their hands for these awkward key combinations.