I was accessing
http://archives.cg70.fr/ during the week with no problems. I'd say they are either upgrading or doing repairs. Hopefully they'll be back up tomorrow.
They have civil records (birth, marriages deaths, etc) and, for most towns and villages, they span 1792 to 1872. Hopefully they will be adding more. They don't have any tables décennales so it makes searching a test of patience.
They have most of the censuses between about 1831 and 1871 on line and a few others - depends on the town. They also have the military records (matricule militaire) but they are just the indexes, not the actual documents.
I didn't see any notice about the site being upgraded but I'm crossing my fingers.
Cheers,
Soosi