Free, and they work right here on the page.
Affirmation checker
Paste an affirmation and the checker scores it on what the research suggests matters: whether you can believe it, whether it says what you want rather than what you don't, whether it's short enough to remember, and whether it's about now. Then it shows you how to fix it.
Everything happens in your browser: nothing you type is sent anywhere or saved.
Your affirmation
Questions
What makes a good affirmation?
One you can believe today, in plain words, about what you want rather than what you don't, short enough to remember. “I’m learning to speak up in meetings” beats “I am a fearless leader”.
Is a low score bad?
No, it's a starting point. Grand lines can feel good to some people; the checker flags them because they backfire for others (the research).