You are free to build your own index and crawler.
The source code is mainly divided into three parts:
Linking structure : https://ahmia.fi/stats/link_graph/
All banned onion services: https://ahmia.fi/banned/.
All known non-banned onion domains: https://ahmia.fi/onions/
For filter requests of onions: https://ahmia.fi/address/
Right onion address starts with msydq and ends with zerdg.onion.
Find real address from ahmia.fi