Nobody counts how many actual hours you work. It's all about your impact and whether you meet your expectations. Some people are much more productive than others, manage their time better and so on... it's a double edged sword though.
France is 35h but for a SWE, there's no fixed schedule and you're not paid by the hour. You get 10 additional vacation days though (so that would be 35 days total).
Downside: If you're oncall, you might have to stay up for 18 hours straight of something big goes wrong, and you won't get paid any overtime.