Expat here, moved to Paris with my SO a few years ago, both working in software development. It's true that everyone here must know some English, but the avera

Expat here, moved to Paris with my SO a few years ago, both working in software development. It's true that everyone here must know some English, but the average level is bad to atrocious (even among people in their early 20s), and like others in this thread have said, many people hate being forced to switch to English for a colleague who can't be bothered to learn French. You may get by professionally (assuming a company is even willing to hire you if they know all your colleagues will hate you; think "culture fit" for a Silicon Valley way of putting this), but you will not be treated in a welcoming way and will de facto be excluded from conversations at lunch, in breaks, and at social events. I've seen this happen to expat colleagues. All this gets much better if you show that you are putting in the effort and learning, even if your current level is poor. Really, if you settle anywhere, learn the language. Especially in France. French is neither super easy nor particularly beautiful IMHO, but it's not rocket science either. Not putting in the effort will harm you both professionally and socially.