For job interviews to fill a technical role it's obvious that the questions needs to be, well, technicals, with focus on the hard skills questions aiming to know the candidate's knowledge in a specific framework, code language, software, etcetera.

But the attitude is very very very... very much... important. I said it before:

Everybody has access to the same documentation, to the same in-house training programs, to the same software, to everybody's code, to basically the same people to ask questions and to learn from... and what's set the difference between someone progressing in his or her line of work and someone stuck is the personality each developer has.

Soft skills related questions allow you to get to know the human you are interviewing, having in mind that you'll share with that person more than some lines of code if you ended up offering the job.

It also humanise the interview. If you pay attention people are usually tense answering the technical questions but when you throw in a soft skills one candidates relax and enjoy the conversation created around that question.

Developer’s work success being too much about personality rather than hard skills
Everybody has access to the same documentation, the same in-house training programs, to everybody’s code, to the same people to ask questions and to learn from... and what’s set the difference between someone progressing in his line of work and someone stuck is the personality each developer has.

At my current job we have a few very good soft skills questions I would like to share now in case you find them useful (our interviews are for web developers so the questions, while soft skills related questions, orbit around that role).

What do you think makes a good developer?

I personally expect whatever answer that's not about code, software, or any other hard skill stuff.

People usually talks about the ability of being flexible, passionate about it, the importance on working as part of a team, etcetera. Still some candidates mention hard skill stuff not covered before in the interview such as testing, and that's fine.

What do you think makes a good manager?

I like this one because it's a chance for the candidate to talk about others, and it's expected that they think of their current boss (obviously).

The answer will give you an idea of how the candidate works on a team structure where somebody is on a position above them. And at the same time it will hint you if the candidate will do well with the current managers at your company.

I like the answers about leadership and motivation.

What do you think you would add to the team if you were to get the job?

This is the polite version of "Why do you want this job besides money?".

I like this one because it forces the candidate to summarise what's their contribution to the team. And it's important to emphasise the team in the question, like you are not just adding something to the company but adding something to a team made of real humans.

What would you expect from the team if you were to get the job?

In opposition to the previous one, this is the time for the candidate to tell us how they see themselves after any period of time as part of a new team.

Again, we are asking about the team, not the company, so we try to keep it human while guiding the candidate into giving us something not technical.

If you were to organise a work social night out, what would you plan?

This always takes the candidates by surprise. They are thinking about PHP, VueJS, code reviews, pull requests and out the sudden they need to think about beers (because beers is the right answer to a social night out plan).

What do you like to do when you aren't coding?

There's no better question than this one to force the candidate to stop talking about hard skills and say something about their personal life (as much as they want, don't force people into talking about their personal life on a job interview).

It is also fun to learn about others people hobbies.