Last year we would have benefited from buying an ACSI card (
https://www.campingcard.co.uk/ c14 - 22 euros) as we were in France in their low-season June / early July and it transpired that we would have been able to camp at a substantial discount on the two campsites we stayed in.
I'm considering getting one for this year, but I've also now found Camping Key Europe too (
https://campingkeyeurope.com/campingcard/index.php £12.50 via SCR) which gives some discounts including in high season.
Countries we are likely to be camping in this year are France and Germany - with a tent, without a car - with no plans set yet.
Does anyone have any comments on these, or any further recommendations (What I'd really like is a European list of very cheap backpacking campsites!)?