Two free tools
They run on a word list and a reading formula, not on my 10 points, so they cost nothing and need no sign-up.
Phrases buyers ignore
Paste a message and see which lines a buyer has read a hundred times before, with what to say instead.
Ten-second read
Paste a message and see how far a buyer gets in 10 seconds, and how long the whole thing takes.
For a buyer's read of the whole message, with a rewrite, there's the check: £5.