Value Proposition Canvas
Map who the software serves, the jobs they need to get done, and how the product creates value.
Use this before any significant design or development work. Fill the Customer Profile side with real users in mind (jobs, pains, gains), then complete the Value Map with what the software will actually do.
Review the Fit Check section with stakeholders to surface gaps early. Best done in a short workshop with two or three people who know the work, not alone.