Black Blocks - Validate first.
Lunabot - ChatGPT assistant on any webpages
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.
Algo by ChatBotKit - Your Personal AI Assistent
Idea Validator - A customer development tool to help you validate your ideas before building them.
Monica - Monica is an open-source personal CRM to keep track of your friends and family.