DNS Coffee

https://dns.coffee/

DNS Coffee collects and archives stats from DNS Zone files in order to provide insights into the growth and changes in DNS over time.

The website includes information such as the size of different zones. It tracks over 1200 zone files.

It provides searching through the zones files based on domain names, name servers, or IP addresses. It can also visualize the relationship between a domain, the parent zones and the name server in what they call a "Trust Tree".

Debian Code Search

https://codesearch.debian.net/

The code search searches through all the open-source projects included in the Debian project. It supports exact searches and regex matches. Results can be filtered by file type, package, or path.

grep.app: Code search for public GitHub repositories

https://grep.app/

grep.app provides a regex search over a large part of public GitHub repositories. It provides exact string search and RE2 regex expressions, both features not supported by GitHub. Results can be filtered by repository, path, or language (file type).