AI Prompt Toolkit is a free collection of 10 professional prompt engineering tools that run entirely in your browser → Token Estimator — Project token usage and costs → JSON Schema Generator — Create schemas from sample data → JSON Validator — Validate AI output against schemas → Prompt Formatter — Structure messy prompts → Prompt Cleaner — Remove noise and fix formatting → Prompt Variable Extractor — Extract {placeholders} → Advanced Prompt Optimizer — Polish prompts for clarity