But you will stay less hours at the office as well.
And you'll get way more time off.
Also you get to go to the Fontainebleau forest, eat to the "Pates vivantes" in the 9e, and can just walk to buy stuff most of the time. Or roller skate.
Rule of thumb is that half the salary amount (e.g. 120k USD to 60k EUR) in Paris will get you about the same or better quality of life as you have in NYC or SF, once you account for differences in how real estate, taxes, healthcare, and retirement work.
I don't know any dev doing 120K USD (105k EURS)__as a salary in Paris. I doubt there are many. If you want to make this figures, you need to be a freelancer, which means no job safety, looking for clients, and paying for social security and requirements yourself.
French salaries for dev are in the 30k to 70k depending of your level. 70k is rare. You need to be good. To be able to negotiate or have a rare skill.
However 120K USD is not rare in the US. I had proposals for 220k.
$120k in SF is considered poverty level. And 60k Euros in Paris is nowhere close. 60k means you don't just get by you actually can live. I know because I have.
For the retirement bit, that's assuming that France's 110% of GDP debt or so won't balloon in the future and pensions won't be slashed by the time your retire.
But you will stay less hours at the office as well.
And you'll get way more time off.
Also you get to go to the Fontainebleau forest, eat to the "Pates vivantes" in the 9e, and can just walk to buy stuff most of the time. Or roller skate.