Sure. But the level of description that you're giving in an interview can be pretty generic/non-proprietary. If that wasn't the case, then you really can't reuse any knowledge from job to job and that's just not so.

Sure, every company is going to have their 'special sauce' components, that ARE proprietary, but nobody's going to expect you to unpack those.

I doubt it's common, but my friend had an experience where they kept trying to direct him towards specific technical topics of particular interest to the business.

He worked for their competitor, but not in the capacity the interviewer was trying to delve into, so in addition to scummy, it was pointless and annoying.

At some point my friend cut the interview off.

Which is the proper thing to do.

Most people barely consider this. In the old days, before leet code interviews, I had people give me code samples. One guy gave me a code sample from some telecom carrier's billing system. It wasn't good. It was also bad that he gave us a proprietary code sample, so he got no points for that either.

How could you ever interview anywhere if you couldn't provide details of the projects that you worked on?

I have a relative who works on very secretive stuff for big companies as a chemist.

His interviews are humorous. Those leading the interviews can't tell him what he'll be working on, and he can't tell them what he's done in the past.

The questions tend to be very theoretical, instead.

Leetcode questions?

(Don't kill me, you all. I'm joking).

So no one else can never build todo app or blogging system?

There is term called prior art an for me if you write bunch of props to database like text/numbers it is basically done in every other system.

Unless you build novel db system of course.

> I'm not a lawyer, but wouldn't anything you or anyone else developed on company time at another company be owned by that company and thus proprietary?

In theory yes, in practice ... if that's true, why would anyone ever hire you for your experience? You wouldn't be allowed to use it.

(coming from the standpoint of a historically non-technical individual contributor who is leaning towards technical now, and asking because I want to learn):

But isn't that exactly why you as an interviewer would pose a problem, set up the context that is potentially similar to the work your project would require, and see how the interviewee navigates that?

Yes, it is. I would want to know how a person solves my problems.

And I sure would hope they bring all their experience to bear! Just because they learned about CDNs at their previous job and “everything is proprietary”, I don’t want them to suddenly forget how CDNs work.

Very little is actually unique between software businesses. We’re mostly just doing data bureaucracy.

So, nobody can never do again anything that he/her do to become a expert?