> Is it okay to bring this up when the interviewer asks why I am looking
> for a new job?


Absolutely.
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In the software development industry, some employers just don't keep up from a pay perspective.  What I would caution you on is to **not make it the only reason**.  If cash is the **only** reason you may come across as only concerned about money. (we all work for money, but employers want to hear that you interested in more than that)

When they ask, you can say something like "*Lack of growth opportunities*" which is typically understood as your current company not having promotion opportunities or providing the ability to get a decent pay raise.