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Grammarly is the best everyday pick because it follows you everywhere, LanguageTool is the only one you can self-host or call from an API, and PerfectIt is the one professional editors actually buy. All five were compared on real pricing, language coverage, deployment options and API access, plus the one named benchmark that measures LLM error-fix accuracy.
Grammarly is the right default for most people. LanguageTool is the better answer if you write in more than one language or need the checker inside your own network, and PerfectIt is the only tool here that catches the document-wide inconsistencies an editor gets paid to find.
A typo in an email is annoying. A typo in a contract, a book, or a client report can cost money and trust. Proofreading software exists to catch those slips before a human reader does. In 2026 the field splits into two groups: always-on checkers that live in your browser, and large language models that can review a whole document like a junior editor.
This guide covers the best tools, then folds in two phrases people actually search for: AI proofreading software for editors and proofreading examples. The goal is simple language and a setup you can use today.
Proofreading is not the same as rewriting. A good tool flags spelling, grammar, punctuation, consistency, and clumsy sentences. It should not flatten your voice or invent facts. That line matters more now that AI can rewrite a page in seconds.
Why You Need Proofreading Software
- The expensive errors are the boring ones. A wrong number in a contract or a misspelled client name costs more than an awkward sentence ever will.
- Consistency is invisible to you and obvious to readers. Nobody notices "email" in chapter one until they hit "e-mail" in chapter four.
- Machine passes are effectively free. Clearing mechanical errors before a human reads means the human spends their time on meaning.
- Multilingual teams need one standard. One tool covering 30-plus languages beats four tools covering one each.
- Privacy is now a real constraint. Unpublished manuscripts and client contracts should not be pasted into a cloud service your legal team has not approved.
How We Evaluated
Each tool was scored on four things: pricing transparency, including what the free tier genuinely allows; checking depth, separating sentence-level grammar from document-wide consistency; AI, MCP and API maturity; and deployment flexibility, meaning self-hosting, offline operation and language coverage. Prices came from each vendor's own pricing or support pages in September 2026. Full criteria live in our methodology.
The Best Proofreading Software Right Now
1. Grammarly
Still the default for most people. It checks grammar, punctuation, clarity, and tone in the browser, Word, Google Docs, and email. The free plan is useful. Pro adds full-sentence rewrites, tone controls, and plagiarism checks. Grammarly is the strongest everyday product because it sits where you already write. One caveat: it can push prose toward a generic "professional" style. Accept the error fixes. Be picky about style.
Pricing: Free at $0, with unlimited basic grammar, spelling and punctuation checks plus 100 generative-AI prompts a month and no word cap. Pro lists at $30 per member monthly, but drops to $144 a year, which works out near $12 a month, and includes 2,000 prompts. Pro caps at 149 seats. Enterprise is custom-quoted.
Top Features
- Full-sentence rewrites
- Tone adjustment and detection
- AI prompts for generation
- Plagiarism and AI-text detection
- Style guide plus brand tones
- Inclusive-language and citation checks
Pros
- The widest surface coverage here, following you across apps and operating systems
- Real plagiarism and AI-text detection, which most rivals lack
- A genuinely useful free tier with no word limit
Cons
- Monthly billing costs 2.5 times the annual rate, which is the widest gap in this guide
- No self-hosting, and no grammar-suggestion API since the Text Editor SDK was retired in January 2024
AI/MCP Integration: Community only. Several third-party servers exist, but they wrap Grammarly's web interface rather than a sanctioned API, and Grammarly publishes none itself.
API Integration: Yes, but enterprise-scoped and narrow. The developer API covers analytics, license management, writing score, and AI and plagiarism detection. There is no endpoint that returns grammar suggestions.
Languages: 20-plus, with 23 named officially, five English dialects, and in-line translation into 19 languages.
Plagiarism Checker: Yes, on paid tiers.
Best for: daily email and web copy, and anyone who wants one checker everywhere.
Editor score: 4.6/5. The most useful tool here for the most people. The monthly-versus-annual gap and the missing suggestion API are what keep it from a higher mark.
2. ProWritingAid
Best for long documents. It runs dozens of reports: repetition, sticky sentences, pacing, dialogue tags, overused words. Novelists, journalists, and anyone editing a manuscript get more depth here than from a green underline. There is a free word-limit plan and a lifetime license if you hate subscriptions.
Pricing: Free at $0, capped at 500 words per check, with 10 rephrases and three sparks a day and two free plagiarism checks at signup. Premium runs $30 a month, $120 a year, or $399 for a lifetime licence, and Premium Pro $36, $144 or $699. Those paid figures come from secondary sources rather than ProWritingAid's own page, which geo-serves currency by country, so treat them as indicative and check your own checkout.
Top Features
- 25-plus in-depth writing reports
- Line-editing and rephrase suggestions
- Chapter critique and manuscript analysis
- Plagiarism checks sold in bundles
- Scrivener and Vellum integration
- Fiction pacing and dialogue checks
Pros
- The deepest report suite in the category for book-length work
- A lifetime licence, which almost nobody else offers
- Native Scrivener and Vellum support for novelists
Cons
- English only, across five dialects
- The API was officially retired, so it cannot serve an automated pipeline
AI/MCP Integration: None. There is no first-party server and no credible community one, largely because there is no API left to build on.
API Integration: No. ProWritingAid's own help centre states it no longer offers an API.
Languages: English only, covering General, British, US, Australian and Canadian variants.
Plagiarism Checker: Yes, sold in bundles of 10 to 1,000 checks, each covering up to 2,000 words.
Best for: books, blogs, long reports.
Editor score: 4.2/5. Unmatched for manuscripts. Being English-only with no API rules it out for multilingual teams and anything programmatic.
3. LanguageTool
Best free and multilingual option. It supports 30-plus languages, has a generous free check, and can be self-hosted if you do not want text leaving your network. Teams that write in English plus German, Spanish, or French often start here.
The self-hosting claim holds up, and it is properly documented: download the snapshot, run the embedded HTTP server, or install it via Homebrew on macOS. One caveat worth knowing before you plan around it, in LanguageTool's own words: the self-hosted build gives you a basic server without the AI-based rules, which are cloud-only. On-premises users get a materially weaker checker than cloud users.
Pricing: Free at no cost, capped at 2,000 characters per text field. Premium is €19.90 a month or €59.89 a year, which works out near €4.90 a month, and lifts the cap to 150,000 characters. Teams is €56.90 per user per year for up to 20 users. LanguageTool publishes its prices in euros only, with no USD equivalent on its own help pages, so those are stated as the vendor states them. The proofreading API is tiered separately by calls per day.
Top Features
- 30-plus languages for grammar and style
- 20,000-plus extra premium checks per language
- AI paraphrasing and rephrasing
- Custom style guide rules
- Team dictionary and shared terms
- Personal dictionary synced across devices
Pros
- The only tool here that genuinely runs on your own hardware, with an open-source core
- 30-plus languages against Grammarly's 20-plus and everyone else's one
- A real, documented public API tiered by usage
Cons
- The self-hosted build ships without the AI-based rules
- No plagiarism checker at all, and pricing is published in euros only
AI/MCP Integration: Community only. At least two community MCP servers exist and both require a paid Premium API key.
API Integration: Yes, and the only genuinely open one in this guide, accepting up to 60,000 characters per request without storing text.
Languages: 30-plus, stated on both its Premium and API pages.
Plagiarism Checker: No.
Best for: more than one language, and any team that cannot send text to a cloud service.
Editor score: 4.5/5. On deployment freedom and language coverage nothing here comes close. The AI rules being cloud-only undercuts the main reason to self-host in the first place.
4. Hemingway Editor
Not a full grammar engine. It is a readability scalpel. Long sentences turn yellow or red. Adverbs and passive voice get highlighted. Use it as a last pass when the grammar is already clean and you want punch.
That description needs one update, though. Hemingway is no longer purely a readability tool: the paid tier now adds AI sentence rewrites, advanced grammar fixes, eight tone and style presets, document review with feedback, and AI synonyms.
Pricing: The free web editor has no word limit and no AI sentences. Editor Plus is $8.33 a month billed annually at $100, for 5,000 AI sentences a month, or $12.50 a month at $150 a year for 10,000. Team is $12.50 per user a month. The older Editor Classic desktop app is a one-time $19.99. There is a two-week Plus trial with no card.
Top Features
- Readability grade-level scoring
- Highlights for wordiness and passive voice
- AI sentence rewrites
- Eight tone and style presets
- Document review and feedback
- AI synonym suggestions
Pros
- The clearest single-purpose readability signal anywhere, free and uncapped
- A one-time $19.99 desktop licence that works fully offline
- Prices display in USD globally, unlike most of this category
Cons
- It lives in its own window, with no Word, Docs, email or browser integration
- English only, since its readability metrics are English-specific
AI/MCP Integration: None. No first-party server, and the generic no-code connectors that exist are not real integrations.
API Integration: No developer API or documentation is published.
Languages: English only. This is not stated explicitly on Hemingway's site; it is inferred from the absence of any language documentation as of September 2026.
Plagiarism Checker: No.
Best for: a final punch-up pass once the grammar is clean.
Editor score: 4.0/5. Does one job better than anything else and refuses to do any other. Being a destination rather than an always-on layer is the real cost.
5. PerfectIt
Built for professional editors working in Microsoft Word. It checks house style: hyphenation, capitalization, numbers, abbreviations, and whether you wrote "email" in chapter one and "e-mail" in chapter four. If you edit books, reports, or legal text for a living, this is the consistency tool Grammarly is not.
One correction to the common description, including an earlier version of this guide: it is Microsoft Office only rather than Word only. The Elite tier adds PowerPoint, and PerfectIt Cloud runs in Word on Mac, iPad and Microsoft 365. It is officially unavailable for Google Docs and OpenOffice.
Pricing: No free tier, only a 14-day trial with no card. Professional is $10 a month, billed $115 annually, for one to three users. Elite is $12 a month at $145 a year and adds PowerPoint. Team is $13 a month at $155 a year for three to 100 users. Enterprise is $583 a month at $7,000 a year. Members of editing associations including ACES, CIEP and AMWA get at least 30% off.
Top Features
- Consistency checks across a whole document
- Acronym and abbreviation definition checking
- House-style and client style-sheet enforcement
- Regional spelling consistency
- Hyphenation and capitalization variants
- Table, bullet and list numbering checks
Pros
- The only tool here that finds document-wide inconsistency rather than sentence-level errors
- The Windows edition never connects to the internet or any network, so documents never leave the machine
- Built-in style sheets for UN, EU, WHO, GPO and Chicago among others
Cons
- Microsoft Office only, and explicitly not available for Google Docs
- English only, and no API or CLI of any kind
AI/MCP Integration: None, first-party or community.
API Integration: No API, CLI or developer documentation.
Languages: English only, with UK, US, Canadian and Australian style sheets plus institutional and legal styles.
Plagiarism Checker: No.
Best for: house style in Word, and anyone editing for a living.
Editor score: 4.4/5. The most genuinely specialist tool in this guide, and the offline Windows build is a real answer to the confidentiality problem. Office-only and English-only keep the score where it is.
Also Worth a Look
Paperpal for academic papers, at $144 a year for Prime, with a free tier giving 200 language suggestions a month and a 7,000-word plagiarism check. Microsoft Editor if you already live in Word and Outlook, free in the browser and bundled into Microsoft 365 Personal at $9.99 a month. QuillBot if you need paraphrase plus a grammar pass, free up to 125 words in the paraphraser. DeepL Write for smoothing bilingual drafts, free up to 1,500 characters without an account and the strongest non-English fluency rewriting of the group.
Comparison Table
| Tool | Best For | Starting Price | Standout Feature | AI-MCP Support | API Integration |
|---|---|---|---|---|---|
| Grammarly | Daily email and web copy | Free; $144/yr Pro | Works in nearly every app | Community only | Enterprise, no suggestions |
| ProWritingAid | Books and long reports | Free 500 words; $120/yr | 25-plus writing reports | None | No, officially retired |
| LanguageTool | More than one language | Free 2,000 chars; EUR 59.89/yr | Genuine self-hosting | Community only | Yes, tiered by calls |
| Hemingway Editor | Readability punch-up | Free, no word limit | Grade-level scoring | None | No |
| PerfectIt | House style in Word | $115/yr, no free tier | Document-wide consistency | None | No |
Checking work that an AI wrote rather than a human? Our AI content detectors guide covers the other side of this problem, and AI content creation software covers the drafting stage.
AI Proofreading Software for Editors
Editors need more than a squiggly line. They need a second reader that can follow a brief, keep the author's voice, and return a change list instead of a rewritten file.
That is where general models earn a place next to Grammarly. Independent 2026 tests of proofreading accuracy put OpenAI's GPT-5.6 Sol and Anthropic's Claude Opus 5 at the top of dedicated error-fix benchmarks, with Claude often faster and cheaper per pass.
Those results are worth naming rather than gesturing at, because you can check them. The benchmark is ErrataBench, which tests 41 models on roughly 99,000 words of real literature, legal and technical text seeded with realistic errors, giving every model identical prompts, tools and turn limits. On its results, GPT-5.6 Sol leads at a 96.5% fix rate, with Claude Opus 5 second at 95.7% while running cheaper per pass and roughly 2.7 times faster.
One disclosure matters here, and most write-ups citing these numbers skip it: ErrataBench is published by Revise, a commercial vendor that sells a multi-model editor and appears in the tool list below. Its methodology and raw results are public and reproducible, which is more than most vendor benchmarks offer, but it is not an independent test. Treat the ranking as credible and interested, not neutral.
Practical tools for editors:
- Claude — Strong on long documents and conservative edits. Ask it to list errors, not rewrite the chapter.
- ChatGPT — Flexible if you give it a checklist (spelling, agreement, consistency, citations).
- Revise — A document editor that can run more than one model on the same file and return comments or tracked-style changes. Free tier, then $8 a month for Plus and $20 for Pro.
- Word + Copilot / Google Docs + Gemini — Fine for in-place review if the file already lives there.
New suggestion for editors: run two passes, never one.
Pass 1: Grammarly, LanguageTool, or PerfectIt for mechanical errors.
Pass 2: Claude or ChatGPT with a frozen brief: "Do not rewrite. Flag only real errors and inconsistencies. Keep the author's wording unless the sentence is ungrammatical. Return a numbered list with quote + fix + reason."
That workflow keeps speed and still leaves a human in charge. AI is a cheap first reader. It is not the last signature on the page. If you want to understand what you are actually buying in pass two, our large language models comparison has the pricing and context limits.
Proofreading Examples You Can Copy
Abstract advice does not train the eye. Here are proofreading examples of the mistakes tools catch well, and the ones they still miss.
1. Agreement
Wrong: "The list of sources are incomplete."
Right: "The list of sources is incomplete."
Most checkers catch this.
2. Homophones
Wrong: "Their going to loose the contract."
Right: "They're going to lose the contract."
Good tools catch this. Weak tools miss "loose/lose" in a long paragraph.
3. Comma splice
Wrong: "The draft is late, the client is waiting."
Right: "The draft is late. The client is waiting."
Or use a semicolon. Hemingway will also flag the rhythm.
4. Consistency (the editor's job)
"Website" in the intro, "web site" in the appendix. "10%" then "ten percent." PerfectIt is built for this. Chatbots catch it only if you ask.
5. False friend from AI
The model "fixes" "which" to "that," or turns a sharp short sentence into a longer "professional" one. That is style, not an error. Reject it.
6. Fact that looks like grammar
"The meeting is on Tuesday, September 12, 2026." If your calendar says Friday, no grammar app will save you. Proofreading software does not replace a fact check. For the record, that date actually fell on a Saturday, which is exactly the kind of error only a human or a calendar catches.
Use a short sample of your own writing, one messy email and one page of formal copy, and run it through two tools. Compare what each flags. That ten-minute test tells you more than a feature table.
What This Actually Costs
Take a five-person editorial team on annual billing. LanguageTool Teams is the cheapest real option at roughly 57 euros per user per year, or about 24 euros a month for the team. Grammarly Pro comes to $720 a year, around $60 a month. Hemingway Team lands at $750, and PerfectIt Team at $775, so roughly $63 and $65 a month.
Add an AI second pass and the maths barely moves. A full ErrataBench-scale run costs under a dollar on Claude Opus 5, so a realistic monthly volume of document passes adds single-digit dollars rather than another subscription. That is the genuinely new thing about this category in 2026: the second reader is now the cheapest line item in the workflow.
How to Choose (and a Stack That Works)
Pick by the job, not the logo.
| You write… | Start with |
|---|---|
| Daily email and web copy | Grammarly |
| Books, blogs, long reports | ProWritingAid |
| More than one language | LanguageTool |
| House style in Word | PerfectIt |
| Journal articles | Paperpal plus a human editor |
| Client-ready files | Checker plus Claude or ChatGPT plus your eyes |
New suggestion: build a one-page "house brief" and paste it above every AI pass.
Example: "Audience: busy managers. Tone: plain, direct. UK or US spelling: US. Do not use 'leverage,' 'utilize,' or 'in order to.' Numbers: numerals for 10 and above. Keep headings. Do not add new claims."
Save that brief. Reuse it. The software gets smarter because your instructions get sharper.
Also keep a human layer for anything public or legal. Paid human desks still exist for a reason, services such as Editor World and Cambridge Proofreading sell a person, not a model. Current rates run from about $0.021 per word at Editor World, and $28.90 per 1,000 words on 24-hour turnaround at Cambridge Proofreading. Use AI to cut the cheap errors so the human spends time on meaning.
One note if you go looking: the trademark holder is Cambridge Proofreading LLC at proofreading.org. A separate site trades under a similar name with no company attribution, which is worth checking before you send a manuscript anywhere.
Final Thoughts
The honest summary of this category in 2026 is that the machine layer has been commoditised and the human layer has not. Every tool here catches agreement errors and comma splices. None of them will notice that the Tuesday in your contract is a Saturday, and the one thing that has actually changed is that a competent second reader now costs cents rather than a salary.
So spend your budget on the specialist, not the generalist. Grammarly or LanguageTool will handle the mechanics for the price of a coffee. What is worth paying for is PerfectIt if you edit for a living, or a human desk if the document is going to be signed.
More comparisons live in our AI and automation section, and AI grading tools covers the education-specific end of this problem.
