Side-by-side comparison · Writing & Translation
Grammarly vs Originality.ai vs Undetectable AI
Everything that matters when choosing between them, in one place: our rating, what each can do, what they cost, and the trade-offs.
Comparing 3 tools, the maximum.
At a glance
Pick it if: Anyone who writes emails, documents and messages at work and wants mistakes caught and tone checked before they hit send.
Pick it if: Publishers, content agencies, SEO teams and businesses that commission written content and want to check it before publishing.
Pick it if: Marketers and writers who use AI for first drafts and want them to sound less robotic.
Grammarly scores highest overall, but Originality.ai gives you more for your money. Which one is right comes down to what you value most.
Overview
| Attribute | Grammarly | Originality.ai | Undetectable AI |
|---|---|---|---|
| In one line | Fixes grammar, clarity and tone in your writing, wherever you type. | Checks content for AI writing, plagiarism and factual errors before you publish it. | Rewrites AI-written text so it reads more human and is less likely to get flagged. |
| Pricing model | Freemium | Freemium | Freemium |
| Starting price | $12/member/mo | $14.95/mo | $0 |
| Free plan | Yes | Yes | Yes |
| Works with Claude Code | No | Yes | Yes |
Rating breakdown
Our scores out of 5. The higher bar in each row is highlighted.
| Attribute | Grammarly | Originality.ai | Undetectable AI |
|---|---|---|---|
| Overall rating | 4.3Winner | 4.1 | 3.6 |
| Ease of useHow quickly someone non-technical gets value from it. | 5.0 | 4.0 | 4.0 |
| FeaturesHow completely it covers its own job, and how well the pieces fit together. | 4.5 | 4.5 | 3.5 |
| Output qualityHow good the results are before you fix them. | 4.0 | 3.5 | 3.0 |
| Value for moneyWhat you get for the price, including the free plan. | 3.5 | 4.0 | 3.5 |
| Speed & reliabilityHow fast it is and how often it falls over. | 4.5 | 4.5 | 4.0 |
Feature comparison
A tick means it does this today. A dash means we haven't checked.
| Attribute | Grammarly | Originality.ai | Undetectable AI |
|---|---|---|---|
| Access & platform | |||
| Free plan | Yes | Yes | Yes |
| Mobile app | Yes | – | No |
| Desktop app | Yes | – | – |
| Browser extension | Yes | Yes | Yes |
| API access | – | Yes | Yes |
| Teams & business | |||
| Team workspace | Yes | Yes | No |
| Enterprise plan or SSO | Yes | Yes | – |
| Connects to other apps | Yes | Yes | No |
| Open source or self-hosted | No | No | No |
| AI abilities | |||
| Works with your files | – | Yes | Yes |
| Understands images | – | – | Yes |
| Makes images | No | No | No |
| Makes video | No | No | No |
| Writes code | No | No | No |
| Runs agents or automations | – | No | No |
| Learns your brand or style | Yes | – | – |
| Works in many languages | – | – | Yes |
| Capabilities score | 8/ 17 | 7/ 17 | 6/ 17 |
Pricing
Plans as listed on each vendor's site when we last checked. Confirm before you buy.
| Attribute | Grammarly | Originality.ai | Undetectable AI |
|---|---|---|---|
| Plans | Free Free Basic spelling and grammar checks. | Free Free Checking the odd article. | Free $0 Testing one short piece. |
ProOur pick $12/member/mo billed yearly, or about $30 monthly Anyone who writes a lot at work, alone or in a team. | ProOur pick $14.95/mo, or $12.95/mo billed yearly Agencies and site owners checking content every week. | 10K words $9.99/mo, or $5/mo billed yearly ($60) Occasional use. | |
Enterprise Custom Large organisations with security needs. | Enterprise $179/mo, or $136.58/mo billed yearly Publishers and large content teams. | 20K wordsOur pick $19/mo, or $9.50/mo billed yearly ($114) Regular blog content. | |
Larger plans From $31/mo, or $15.75/mo billed yearly Agencies and high volume. | |||
| Which plan to pick | Free is enough for typo-catching. If you write for clients or customers every day, Pro on yearly billing is good value; paying monthly costs more than double. | Pro is enough for most agencies and site owners. An AI and plagiarism check together uses two credits per 100 words, so budget about 100,000 words of checked content a month. Go Enterprise only if you need the API or very high volume. | Test the free 250 words on your own writing first. If the output works for you, a small yearly plan is cheap. Word credits reset monthly, so don't buy more than you use. |
Key features
| Attribute | Grammarly | Originality.ai | Undetectable AI |
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Pros and cons
| Attribute | Grammarly | Originality.ai | Undetectable AI |
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Who each one is for
| Attribute | Grammarly | Originality.ai | Undetectable AI |
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Questions people ask
Which is better, Grammarly, Originality.ai or Undetectable AI?
Grammarly scores highest overall in our ratings (Grammarly 4.3/5, Originality.ai 4.1/5 and Undetectable AI 3.6/5). Grammarly is best for proofreading emails and documents as you type and checking tone before a tricky message goes out. Originality.ai is best for checking freelance and agency content and AI and plagiarism checks in one scan. Undetectable AI is best for Making AI drafts sound less robotic and seeing how detectors might score your text.
Which is cheaper, Grammarly, Originality.ai or Undetectable AI?
Grammarly: There's a free plan, and paid plans start at $12/member/mo. Originality.ai: There's a free plan, and paid plans start at $14.95/mo. Undetectable AI: There's a free plan, and paid plans start at $0.
Which is easier to use, Grammarly, Originality.ai or Undetectable AI?
Grammarly rates highest for ease of use in our scores. Anyone who writes emails, documents and messages at work and wants mistakes caught and tone checked before they hit send.
How we compare
Ratings are our own, from using each tool, across ease of use, features, output quality, value for money, speed & reliability.
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