These websites are provided free of charge. If you're interested then why not start your own site.

Sites might cover a specific period in history -

Pre-history, Roman, Victorian, etc.

They might cover historical events -

WW1, WW2, etc.

They might look at historical subjects -

Industrial revolution, Railways, Archaeology, etc.

If you are interested in starting your own then read on.
Alternatively suggest this site to a friend who you think has a historical project that they'd like to share.