How to display results from multiple indices?

It's actually pretty simple, and can be done both for the Autocomplete and the Instant Search results page.

1/ Multi-Category AutocompleteYou can follow our multi-categories autocomplete tutorial that explains how to perform the same query on multiple indices and display results in the same auto-completion search box.2/ Multi-Category Instant Search results pageThe easiest way is to duplicate your search code: doing a search on two indices is the equivalent of doing two separate search operations.If you're not using the Javascript helper, but an API client directly, you can also batch your queries.As a side note, searching on N indices will generate N search operations, which has an impact on the pricing.