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.
IdeasAI - OpenAI-powered startup idea generator
Idea Validator - A customer development tool to help you validate your ideas before building them.
The 25 Days of Ideas - Free resources for coming up with startup ideas