HumanFlow vs Grammarly

An earlier version of this comparison said Grammarly did not offer AI humanizing. That was incorrect. Grammarly publishes a free AI humanizer, and a Humanizer agent with four voices and a custom voice profile built from a 200-word writing sample. The same earlier version said Grammarly's AI detection sat behind Pro; its standalone AI detector is free.

Both errors made us look better than we are. We are correcting them here rather than quietly editing, because a page whose entire argument is "check the figures yourself" does not get to skip that when the figures went against it.

Their humanizer page states that the tool "is not intended to bypass AI detectors. Instead, it enhances clarity and coherence, helping AI-assisted writing feel more polished and readable."

It goes further: "In academic settings or any context where AI use is restricted or must be disclosed, using an AI humanizer to disguise the use of AI may be considered unethical and could constitute cheating or plagiarism."

That is a stronger statement than most vendors in this market will make, and it is on the product page rather than buried in terms. We hold the same position — HumanFlow does not promise to beat any detector, because nobody honestly can — but we did not put the cheating warning on the tool page, and they did.

If you came to this comparison expecting us to argue that Grammarly is soft on the ethics, the opposite is true.

Grammarly's humanizer is aimed at readability. It smooths stiff phrasing so AI-assisted writing reads more naturally, in whatever application you are typing in, across six languages, for free.

HumanFlow is aimed at a narrower job: take a draft, tell you sentence by sentence which lines read as machine-written, and rewrite them in a chosen tone. The detection half is the part that has no Grammarly equivalent — theirs returns a document-level assessment, ours marks each sentence and lands on human, AI, or mixed.

That distinction matters less than it sounds for most people. If you want to know roughly whether a piece reads as AI-assisted, a document score answers it. The sentence view earns its keep when you intend to rewrite, because it tells you which four lines to start with instead of asking you to reread 1,500 words hunting for them.

Grammarly Pro is $30 a month, or $144 a year at $12 a month. HumanFlow Writer is $18 a month, or $10.80 on annual billing. We are cheaper at the subscription level.

That comparison is close to irrelevant, because the Grammarly features that compete with us — the humanizer and the AI detector — are the free ones. The honest framing is not "$12 against $10.80". It is: you can do the core job on Grammarly for nothing, and HumanFlow's free plan gives you 2,000 humanizer words and 10,000 detection words a month.

Where Pro earns its price is everything else: grammar, plagiarism, brand voice, team controls. None of that is a HumanFlow feature, so none of it belongs in a column next to ours.

One geography note, recorded because we hit it: fetched from India, grammarly.com/plans serves rupee pricing for a plan described as exclusive to India, with no dollar figures. The USD figures above come from Grammarly's own support documentation. Check what your own browser is shown.

Use Grammarly. That is the honest recommendation for most people who land here, and it costs nothing to test.

Come to HumanFlow if you specifically want the sentence-level read — which sentences, not what percentage — or if you work on long documents and want a published per-scan ceiling you can plan around. Those are real differences and they are also narrow ones.

We compete in this market and this page is written by one of the two products. Our editorial policy sets out how we handle that, including the part where correcting a mistake makes our own product look worse.

Pick Grammarly if you want a free humanizer, you write in more than one language, you want it inside the apps you already use, or you want grammar and clarity correction as well. For most people reading this page, that is the right answer.

Pick HumanFlow if you need to see which specific sentences read as machine-written, or you work on long documents and want a published per-scan limit rather than an unstated one.

One caveat that applies whichever you choose: HumanFlow is the newer product here. It runs in the browser and on Android, with an iPhone version in development, and the competitors on this page have had longer to accumulate integrations and export options. If you need a specific one of those today, that is a real reason to choose them.