Editing tools all look like a squiggly line and a suggestion. Underneath, they do three different things: fix errors, explain patterns, or produce a different sentence. Choosing the wrong one is why people say the tool is useless when it was simply answering a question they did not ask.
Grammarly, ProWritingAid, and QuillBot represent the three jobs. They are complementary more often than they are alternatives.
The short answer
Use Grammarly as the proofreader that runs everywhere. Use ProWritingAid when you want to see why a paragraph feels weak — it reports patterns, not just errors. Use QuillBot when you already have a sentence you like and need another shape. None of them will structure a piece or find a source.
Grammarly: the universal layer
The product is where it runs: browser, editor, email, everywhere you type. That ubiquity is why it became the default, and it imposes a ceiling: suggestions are short, local, and safe, because they have to fit any context.
For a team, the useful part is style settings and the consistency they impose across people. For a writer, the risk is accepting a suggestion that flattens a deliberately unusual sentence.
ProWritingAid: the analysis
ProWritingAid reports on the whole document: readability, sentence-length variety, repeated words, pacing, and dialogue tags. Each suggestion shows the reasoning, which is the feature that separates it from a proofreader.
That makes it slower and more educational. It is the tool to run on a draft you are proud of and want to improve, not on an email you are about to send.
QuillBot: the rephraser
QuillBot does one thing: given text, produce another version of it. The modes are about shape — shorten, formalise, expand — and the quality is good enough that the tool is genuinely useful for that narrow job.
The failure mode is using it to generate content, which produces a second version of a sentence that was already weak. Garbage, rephrased, is still garbage.
The comparison
| Job | Grammarly | ProWritingAid | QuillBot |
|---|---|---|---|
| Fix errors | Strong | Strong | No |
| Explain patterns | Light | Strong | No |
| Rewrite a sentence | No | Light | Strong |
| Whole-document analysis | Basic | Strong | No |
| Works everywhere | Yes | Mostly | As a website |
The second and third rows are the divide. A proofreader and a style analyst are different products that happen to share a UI pattern.
The editing workflow that uses both
Run analysis before proofreading. ProWritingAid's report tells you whether the piece has an issue with structure or pacing; Grammarly's suggestions cannot fix a paragraph that should not exist.
Then proofread last, with the tool that runs everywhere. Editing in the other order polishes sentences you are about to delete.
What these tools cannot see
Whether the claim is true, whether the source says what the sentence says, and whether the piece answers its own title. Those are the three checks that matter most in published work, and all three are human or retrieval jobs.
That is also why an editing tool makes a published piece feel finished without making it correct — the prose is clean, and the assertion is unchecked.
Frequently asked questions
Can I use both Grammarly and ProWritingAid? Yes, and many writers do: analysis first, proofreading last. Two tools, two passes, no overlap if you order them.
Is QuillBot a plagiarism tool? It has a checker, but it is a rephrasing tool first. Rephrasing existing text to avoid detection is a different and much worse use of it.
Which is best for non-native speakers? Grammarly for everyday text; ProWritingAid when the issue is sentence variety rather than grammar. See writing tools.
Last checked: 10 November 2026.
Related: writing platforms, writing tools after generic voice, and writing tools.
