In all honesty, we don't look to see if a possible candidate is active on either of those sites. That's not saying they aren't important. Just as a Designer can show a portfolio of his work, a developer can use Github as a portfolio of her development. The thing is, unless they are doing this work on the side, chances are the code from their previous/current employer won't be in a public repository. Stackoverflow is good to see if the person gives good advice and knows how to troubleshoot but the questions we ask in interviews do the same thing. We also have a quick test for interviewees to take just to see just how good they might be.

Practical close to real world application and code review are always the best choice to asses a candidates skill.

Github repos and tech blog are tie breakers.

medium.com/javascript-scene/10-interview-question…

As someone who has never published code in a public repository or even written a blog despite many years promising myself to publish this or that project on github, and knowing a good number of excellent developers in a similar situation, I know very much not to give undue importance to these. Like @oded says, there is no better way to make an assessment than to engage a prospect in a problem solving exercise. Some people can talk (or write) impressively about things that they know little about in practice - that is their gift. Equally, some really good practitioners can find it difficult to express themselves - that is the way they are.

I would usually ask for code samples which may or may not be in a public repository, but these can only give you part of the picture. For me software development is more about a certain type of mindset - more so than knowing this or that language or writing code in this or that style or applying this or that methodology.

Just in passing, I know two people, one a company director and the other a lecturer who I think are great programmers that are not software developers !

We hardly even look at those, technical interview, technical test and if we're happy, that's it.

Honestly, every one of those things is a major plus. In rising order:

• Asked questions on SO

• Answered questions on SO

• Has repositories on GitHub

• Contributed to other repositories on GitHub

• Has a technical blog

Those things help, but I think the best way to asses a candidate's technical strength is with a practical test. Let them write some code and then talk to them about their design choices.