I thought it was very questionable, but I was in debt and that was the only job I could get at the time. There's actually a positive use for browser fingerprinting in that it could theoretically detect Mitm attacks or stolen cookies. Basically, if you place a unique cookie on each device, and then a user/device shows up with that cookie but a totally different browser fingerprint, it's possible that the account was hacked. The client I was working for was a bank so I was pushing for it to be used in this way. But realistically, I knew it was probably going to be used for marketing or privacy invasion but felt like I needed to keep the job to pay the bills.