Both tools get recommended for "checking your grammar," but they're built around different jobs. Grammarly's core product is grammar and spelling checking, with paraphrasing and other features added on top. QuillBot's core product is paraphrasing — its grammar checker exists, but it's the secondary tool, not the main one. That difference shows up clearly once you compare what each one's free plan actually includes.
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Grammarly's free plan includes unlimited core grammar and spelling mistake detection, running continuously as you type, plus a tone-visibility feature and 100 AI-generation prompts a month. It's a genuinely complete grammar checker before you ever hit a paywall — the Pro tier (from $12/month billed annually, per Grammarly's own pricing page) adds full-sentence rewrites, active tone adjustment, plagiarism checking, and AI-writing detection on top of that free foundation.
QuillBot's free plan draws its line differently: it covers "basic grammar errors" for free, but reserves "advanced grammar recommendations" for Premium subscribers. The free plan's harder cap is actually on QuillBot's main feature, paraphrasing — 125 words per rewrite, limited to two of its nine rewriting modes. Premium ($19.95/month, or $8.33/month billed annually at $99.95/year) removes that cap, unlocks all nine modes plus custom modes, and adds a 25,000-word-per-month plagiarism checker. Grammar checking on QuillBot is real, but it's not what the product — or its pricing tiers — are built around.
If your main use case is catching grammar, spelling, and punctuation mistakes in an essay, Grammarly's free tier is the more complete tool for that specific job out of the box — it's unlimited and runs continuously, rather than being the secondary feature behind a paraphrasing product. If what you actually want is to rewrite or rephrase sentences (not just catch errors in them), QuillBot's paraphraser is the tool built for that — just know the free version caps you at 125 words per rewrite with two modes.
Neither free plan includes a plagiarism checker without upgrading: Grammarly gates it behind Pro ($12/month), QuillBot behind Premium ($19.95/month or $8.33/month annually). If a plagiarism check is part of what you need alongside the grammar pass, factor that into which paid tier (if either) actually makes sense for how often you'd use it.
StudyPilot's grammar checker catches grammar, spelling, punctuation, word choice, sentence structure, passive voice, run-ons, and comma splices, with a one-click fix and a plain-English reason for each flag — free, with no word limit, and no credit card required to start.
It doesn't replace Grammarly's continuous-as-you-type browser extension or QuillBot's nine paraphrasing modes — those are genuinely different product shapes. But for a student who just wants an essay's grammar checked without hitting a word cap or a feature paywall, it's a third free option that sits alongside StudyPilot's plagiarism checker, AI detector, and paraphraser as separate free tools rather than one subscription gating all of them.
StudyPilot's grammar checker catches grammar, spelling, and punctuation mistakes with a one-click fix — free, with no word limit and no credit card required.
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