When I investigated using livegrep for code search at work, it really struggled to scale to a large number of repositories. At least at the time (a few years ago) indexing in livegrep was a monolithic operation: you index all repos at once, which produces one giant index. This does not work well once you're past a certain threshold.

I also recall that the indexes it produces are pretty heavyweight in terms of memory requirements, but I don't have any numbers on hand to justify that claim.

Zoekt (also mentioned in TFA) has the correct properties in this regard. Except in niche configurations that are probably only employed at sourcegraph, each repo is (re)indexed independently and produces a separate set of index files.

But its builtin web UI left much to be desired (especially compared to livegrep), so I built one: https://github.com/isker/neogrok.