We analyzed 100K technical interviews to see where the best performers work. Here are the results.

At interviewing.io, we’ve hosted over 100K technical interviews, split between mock interviews and real ones.

As it happens, we know where many of our users currently work – they tell us that when they sign up to avoid getting matched for mock interviews with people they work with.

Given that we have this data AND given that we know how well people do in their interviews, we thought it would be interesting to see which companies’ engineers are especially good at technical interviews. We looked at which companies have engineers with the best overall performance, as well as those that shine specifically on technical ability, problem solving ability, and communication skills.

The resulting top ten lists are below!

The setup

On interviewing.io, engineers can practice technical interviewing anonymously. If things go well, they skip right to the technical interview at real companies (which is also fully anonymous). We started interviewing.io because resumes suck and because we believe that anyone, regardless of how they look on paper, should have the opportunity to prove their mettle.

When an interviewer and an interviewee match on our platform, they join a collaborative coding environment with voice, text chat, and a whiteboard, and jump right into a technical interview. After each interview, both parties leave feedback, and once they’ve both submitted, each one can see what the other person said and how they were rated.

Here’s what the feedback form that interviewers fill out looks like:

To arrive at the top ten rankings in this post, we took post-interview feedback data from our users and grouped them by the company where they work. 

About 60% of our users work at FAANG and FAANG-adjacent companies (e.g. Dropbox, Lyft, Uber, Square, etc). The rest work at other large tech companies, startups of all stages and sizes, digital agencies. A small portion are students, some are entrepreneurs, some are career changers, and some are unemployed (as you’ll see in a spicy tidbit below). For context, our average (and median) active user has about 7 years of experience. 

For this analysis, we only included companies where we had at least 50 employees on interviewing.io (which meant that several companies were notably missing because they were just shy of that mark, including Quora, Asana, Stripe, and a few others).

A few words about statistical significance

In all the sections below, we’ve listed the top 10 companies in each category. But how different is the 1st from the 10th, really? As it happens:

1. Membership in the top 10 is indeed highly statistically significant. The companies that made it into our top ten lists do indeed have significantly better interviewees than the ones that did not.

2. Most comparisons within the top 10 are largely insignificant. Though it varies a bit from list to list, in general, the top company is significantly different from the 8-10th ranked companies, except with the communication score, which is very noisy. In other words, a lot of the intermediate ranks could have gone either way.

That being said, here are the lists!

Best overall performance

We looked to see which 10 companies had the highest % of people passing interviews on interviewing.io. The average across all of our users is 54%.

Best technical

We also looked to see which 10 companies had the highest average technical scores in interviews on our platform. The average across all of our users is 2.85 out of 4.

Best problem solving

We also looked to see which 10 companies had the highest average problem solving scores in interviews on our platform. The average across all of our users is 2.79 out of 4.

Best communication

Finally, we looked to see which 10 companies had the highest average communication scores in interviews on our platform. The average across all of our users is 3.22 out of 4. It was surprising to see how high “Unemployed” ranked (that is exactly what it sounds like – these are users who indicated they didn’t have a job when they joined interviewing.io).

Limitations and closing thoughts

It bears mentioning that there are some limitations to our data. As you saw at the beginning, where people work is self-reported, and though we’ve done enough spot checking over the years to be confident that, for the most part, our users are honest about where they work, it’s not a perfect system. People also don’t always update their employer when they switch jobs.

There’s also the issue of selection bias. Maybe we’re just getting people who really feel like they need practice and aren’t an indicative slice of engineers at that company. After having talked to our users for years and after seeing how they perform in real interviews later on, I’m not too sure that’s true, but hey, it’s totally possible.

Finally, there’s the obvious quantity issue. As I mentioned earlier, we’re only including companies where at least 50 of their engineers practiced on interviewing.io. When we lowered that limit, the list started to look different… but we weren’t confident enough in those results (yet) to publish them.

Limitations aside, what does this all mean? I’m tempted to speculate about why Dropbox dominated these rankings and what about their engineers is distinct from many of the other companies with great brands that our users hail from. Dropbox does also hire on interviewing.io, and from what we’ve seen, they have an extremely high bar – many users who’ve done well with other companies on our platform have failed their Dropbox interview. However, I will refrain from speculating beyond that, and I will also refrain from speculating about why certain companies do well on one score but not the others – looking from the outside, we simply don’t know enough about these companies’ inner workings or the nuances of the types of engineers they attract to come up with a credible hypothesis. However, I hope to hear from you, dear reader, if you have visibility into these things and can comment on them.

You might be wondering how this list of companies and scores resolves with interviewing.io’s ongoing refrain about how resumes and pedigree don’t tell you very much about whether someone is a good engineer. We’ve seen over and over that where you go to school doesn’t matter (and in fact, interview performance among students from elite schools doesn’t meaningfully differ from that of students in state schools), but we have seen consistently that where you’ve worked in the past does have some bearing on how you do in interviews.

So, yes, where you work matters. The good news, though, is that it’s not the whole story. We’ve seen in the past that people who take a bunch of Coursera and Udacity classes on topics related to algorithms and data structures tend to perform better than people from top companies who have not. And we’ve seen that after 5 mock interviews on interviewing.io, regardless of where you started or where you work, your chances of passing real interviews will (on average) double.

Of course, the really interesting question in all of this is the holy grail of technical recruiting: Does performance in interviews reliably predict on-the-job performance? While we diligently gather data on the subject, I’d love to hear from you. If you’ve hired engineers from some of the companies in this post, have they performed better than others? Are there any patterns or anti-patterns that you have noticed?