In real life, correct pronunciation is much more important than grammatical knowledge.
Drill Cantonese pronunciation: listen, speak, listen, speak... until Mr. Google can understand your Cantonese.
Simple and easy to use: Just one click to start listening / speaking. No annoying tutorials, tips, requiring user registration, log in, linking to SNS accounts.
Also, you can "share" text from any app (email, browser, messenger) to hear Cantonese pronunciation.