3 Developer Interview Tips

At HubSpot, I do a lot of interviewing for the Dev Team. For more than two years now, I've been talking to candidates that ranged from very disappointing to utterly amazing (of course we've since hired the amazing folks). After interviewing in the neighborhood of one hundred developers I've come up with a bunch of interviewing guidelines, here are my three most valuable tips:

1. Never take basic skills for granted. When interviewing someone with loads of experience I tend to want to skip the basics. More than once this has bitten me when I figured out the candidate has poor logic, design or coding skills. Never assume that experience means skill. Hopefully the candidate will breeze right through your easy questions, if they don't: Fail fast.

2. Ask for the outcome. All candidates should be willing tell you about projects they either spearheaded or contributed to significantly, but not all will be eager to share the outcome. I always ask for the outcome of important projects and what measure they used for success. Great developers either succeeded in a measurable way or failed while learning very important lessons (that they should be able to explain).

3. Have a red flag policy. Ideally, you'll ask a candidate about many different areas of development and be impressed with all of their answers. However, sometimes you'll get good answers in two areas and a complete bomb in the third. I consider the bomb to be a red flag, and seriously reconsider the other areas that didn't seem to be a problem. If your interview questions are chosen to test separate core areas, a single red flag should be enough to disqualify the candidate.

What are your developer interviewing tips?