Readability checker with two established scores
Estimate how demanding an English passage may be using Flesch Reading Ease and Flesch-Kincaid grade level, calculated locally with the supporting averages shown beside them.
This is the free version
Works where you write
PromptDC rewrites selected text in any app, every browser, your IDE and your terminal on Mac and Windows.
One keyboard shortcut
Select text, press Cmd+Shift+E or Ctrl+Shift+E, review the result, then Replace or Copy. It never presses Enter for you.
Your profiles, your models
Pick a default profile per app, or bring your own API key on the Lifetime plan.
Free here: unlimited, this utility runs entirely in your browser. In the app: from $9/mo, or Lifetime from $69 with your own API key.
Readability formulas are useful comparison tools, not judgments about accuracy or writing quality. This checker counts words, sentences, and estimated syllables, then exposes average sentence length and syllables per word so you can see what drives each result. Names, abbreviations, specialist vocabulary, and non-English text can affect syllable detection, so every score is clearly labeled as an estimate. Processing stays in your browser and unlimited checks require no account.
Common questions
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