[relaunched]

There are two plays you can make by listing a side project. For example, if the project is in some way commensurate to the role. For example, if you are applying for a VP of engineering job at a large technology company and your side project is co-author and commit rights to a major open source project, say Python or a well known and use library and you're actively involved.

Or, if it's on the resume to demonstrate you're still actively hands on and you believe that is valuable to the role.

However, if you wouldn't talk about it in an interview, don't put it on your resume. If it wouldn't help you get the job, I wouldn't talk about it in the interview.

[quickthrower2]

It’s about strategy: you don’t know what the interviewers are looking for. Being human they may be dazzled by side projects and it may help get the job at company A because person 13 was interviewing that day but make no difference at B and C. But you get more offers and negotiate a better compensation at B.

In other words interviews are human and messy, not strictly logical.