Comment by ninly

'indexes' has been a just-fine variant of the plural for a very long time -- actually it's the first one listed in Merriam-Webster, so probably the more common variant, though I haven't dug into other references. That said, you're correct that the more common or preferred variant will depend somewhat on the culture/community/industry. The house style guides in finance probably tend toward 'indexes' -- in part because an index is a branded product they produce, so consistency is important -- while software/tech companies (or at least people in them) may tend prefer 'indices'.