Thanks for the pointers to those projects, they look great. I checked out one, and it is does indeed seem to use a proxy to communicate with S3 data (rather than going directly to S3 API).
On top of Kui, this client adds some S3 support, and that's it. The rest (the REPL, the monaco editor previewer, etc.) are all Kui, and thus already open sourced. Any kind of branding is possible, e.g. it could fly official CommonCrawl banners, iconography, etc., if so desired. We will be open sourcing the S3 bits soon, and could also open source a CommonCrawl branding alongside... if so desired!
Anyway, again, this has been mostly brainstorming, based on some local activities we've had against CommonCrawl (happy to talk about those, too, soon). The ability to browse went a long way in our ability to tell stories about the data, and our analyses thereof.
The client currently previews the compressed data files (e.g. wat.gz), but to limit load, only shows the first couple hundred lines -- i.e. no arbitrary pagination was an intentional choice to avoid undue load against the data sets. But we could also offer arbitrary pagination, if deemed valuable.