Black Blocks - Validate first.
Validated ideas - List of 5,000 poorly executed but popular apps
Lean Canvas - Business plans take too long to write, are seldom updated, and almost never read by others but documenting your hypotheses is key. Lean Canvas solves this problem using a 1-page business model.
Idea Validator - A customer development tool to help you validate your ideas before building them.
Makerbook - A directory of the best free resources for creatives
Google Workspace - Google's encompassing suite of cloud-based business apps.