I work for a very small business and planning to quit soon. The reason being other employees are leaving as well and it's a mess to work there with minimal resources and extra workload on the left over employees. There is no potential for career growth either.
How do I explain this situation on a job interview? Or should I just state 'looking for better opportunities'?
"No potential for growth" is probably your best bet. It's a realistic concern that any employee should have. It shows you consider your professional development a priority where some are happy to just middle out with a livable salary. It is a very palatable reason for a recruiter or hiring manager. It addresses the stagnation at your current employer without doing so directly. And best of all, its true.