Do you trust Indian Developers? They can offer a lower price to dev your app. For ex in France it’s around 40-50k€ for a social network app, and in India it’s around 10-15k€. What’s your experience?

Trust but verify. You need to be on top of them to get a good outcome. Delays are common, revisions are plentiful. You can get good work out of them if you’re willing to put in the time and effort.

I think it’s a mistake to group all Indian developers in the same pot. Yes they’re cheaper but you’re still going to get a mix of good and bad programmers. If you’re not sure how to tell hire a consultant and talk to a bunch of Indian programmers about your needs and their skills. Just like everywhere else, don’t take people on face value… ask for code samples, previous work, etc.