When I interviewed at Google they told me to come back when I had more open source contributions. I already had hundreds of thousands of lines in a prominent open source systems project at the time, so they must really want a lot.

The hiring bar at these places is pretty astronomical. Realistically it’s going to be well out of reach for a majority of even the very best programmers in the world.

I'm guessing most candidates don't have a lot of open source contributions, and "more open source" is one of the standard lines when they don't want to really explain why they passed on hiring.

Don't read too much into it. As an entry level applicant you're only getting a small fraction of anyone's attention and will need to apply Hanlon's razor to interpret most of your interactions.

In my experience the resume screen is a lot tougher if you want to work for them outside the US due to very low supply per demand.

It also depends on the level you're interviewing for. If you're shooting for a mid-level or even semi-senior role, that's very different than if you're shooting for a "has industry-wide impact" kind of role. In the latter case claims of prior impact will be carefully scrutinized to weed out poseurs and liars.

Yeah, it was only a new-grad, entry-level position, and they still wanted a huge volume of open source contributions. I don't know how most people would achieve it - mine were from internships and they still weren't enough.

Sounds insane. Based on our two experiences it seems like the requirements can change a lot. Hopefully if you apply again in a few years they won't require that anymore, but it's hard to say without knowing what are the factors that pushed them to require that in the first place.

What is your advice to do well in the interview - especially about how to conduct yourself during?

Realize that the interviewer wants you to succeed! For an interviewer, a candidate that does great and gets hired is a much better outcome than another hour wasted on a rejection.

(I'm sure they are some toxic interviewers and dysfunctional companies where that's not the case, but you don't want to work there anyway so it doesn't matter.)

A lot of good things flow from there.

First, you should feel a little more relaxed. This generally helps think more clearly, talk more naturally, avoid panicking, etc.

Second, you should shift your mindset to view your relationship with the interviewer as based on cooperation, not antagonism. This generally helps act more friendly and less defensive.

Third, if you were at home cooperating with a friend to solve a difficult problem, would you stay silent, or would you run your ideas off each other? Probably the latter. The same applies here. Unlike your friend, the interviewer is limited in how much information they can give. But again unlike your friend, the interviewer already knows exactly how to solve the problem! So leverage that. Ask them whether your proposed solution makes sense. Ask them whether the time and space complexities of your proposed solution are good enough or if you should keep digging. By the time you start implementing the solution in code, you should be fairly confident that you're going in the right direction. (Sometimes the interviewer won't give much away. Don't panic, it happens—in that case just go for it and hope for the best.)

is there an agreed upon level ladder ?

where can one (I) test to find his position on it ?

I think the initial level is mostly a function of experience. Then depending on your interview results it can go up or down. In my case I interviewed at level 5, and did well enough to be invited to come back for another round at 6.

I was super lucky to work with a gem of a recruiter at one of the FANGs who spontaneously pushed for 6 after my feedback from 5 came back positive. The other FANG was more reactive and didn't invite me back until I told them of the competing offer. So perhaps try pushing for it yourself if your recruiter is not as proactive and you feel you have a shot. Worst case they'll say no. (Or they'll say yes and you'll bomb the next round. That's not supposed to reflect negatively on your first round, although it would likely have affected me psychologically and made me less confident during the comp negotiation.)

I ended up joining a company without levels, so I'm afraid I don't have any more useful information for you than what I gleaned as a candidate.

you got an L6 without CS degree?

How many years have you been working in SW industry ?

~11. Had 4 more before that but not in the SW industry, although loosely related.