
There are 0 good reasons for ever telling an interviewer (whom you likely JUST met) where else you are interviewing.
First, why is that information relevant? Interviewers should be focusing on their own companies and instead of worrying about your other potential opportunities.
Second, many industries are smaller than they appear and you don’t need anyone speaking to other people at other companies; possibly disrupting your search.
Third, it’s simply none of their business!
If you are asked this question in the future, simply state “I’m actively job searching,” and leave it at that.
Often, questions like these are used to gauge how fast a company will need to make you an offer or how aggressive they will have to be with a salary.
The content of these interviews (business meetings) should only be about your skills and experiences as well as the role and what your responsibilities will be so both you and the company can decide if the opportunity is a mutual fit.

I would never answer directly, but sometimes give context of my goals that align with the company I am interviewing with like "I'm actively interviewing at a few other companies that also align with my goal of working for a company that helps customers lead healthier lifestyles", this gives you a way to reinforce why you are a fit for their company!

I totally agree with Jeff. The fact that you interviewed with them should be obvious you are job hunting. If they want you then they should negotiate.

I disagree. If they know you are wanted by others, as you say they want to gauge how fast to make an offer or how aggressive to be with salary. That is a GOOD thing...
Great information , practical advise but hearing this from you is advantageous, let's people know they do not need to feel intimidated and give an "exact", honest answer! Thanks for sharing.