Side-by-side comparison · Writing & Translation

Grammarly 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.

Best overall

Grammarly

4.3

From $12/member/mo

Details Visit

Undetectable AI

3.6

From $0

Details Visit

Comparing 2 tools. Add one more if you like.

At a glance

Grammarly4.3

Best overallEasiest to use

Pick it if: Anyone who writes emails, documents and messages at work and wants mistakes caught and tone checked before they hit send.

Undetectable AI3.6

Pick it if: Marketers and writers who use AI for first drafts and want them to sound less robotic.

Overview

Attribute	Grammarly	Undetectable AI
In one line	Fixes grammar, clarity and tone in your writing, wherever you type.	Rewrites AI-written text so it reads more human and is less likely to get flagged.
Pricing model	Freemium	Freemium
Starting price	$12/member/mo	$0
Free plan	Yes	Yes
Works with Claude Code	No	Yes

Rating breakdown

Our scores out of 5. The higher bar in each row is highlighted.

Attribute	Grammarly	Undetectable AI
Overall rating	4.3Winner	3.6
Ease of useHow quickly someone non-technical gets value from it.	5.0	4.0
FeaturesHow completely it covers its own job, and how well the pieces fit together.	4.5	3.5
Output qualityHow good the results are before you fix them.	4.0	3.0
Value for moneyWhat you get for the price, including the free plan.	3.5	3.5
Speed & reliabilityHow fast it is and how often it falls over.	4.5	4.0

Feature comparison

A tick means it does this today. A dash means we haven't checked.

Attribute	Grammarly	Undetectable AI
Access & platform
Free plan	Yes	Yes
Mobile app	Yes	No
Desktop app	Yes	–
Browser extension	Yes	Yes
API access	–	Yes
Teams & business
Team workspace	Yes	No
Enterprise plan or SSO	Yes	–
Connects to other apps	Yes	No
Open source or self-hosted	No	No
AI abilities
Works with your files	–	Yes
Understands images	–	Yes
Makes images	No	No
Makes video	No	No
Writes code	No	No
Runs agents or automations	–	No
Learns your brand or style	Yes	–
Works in many languages	–	Yes
Capabilities score	8/ 17	6/ 17

Pricing

Plans as listed on each vendor's site when we last checked. Confirm before you buy.

Attribute	Grammarly	Undetectable AI
Plans	Free Free Basic spelling and grammar checks.	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.	10K words $9.99/mo, or $5/mo billed yearly ($60) Occasional use.
	Enterprise Custom Large organisations with security needs.	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.	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	Undetectable AI
Standout features	Live checking everywhere Clarity and rewrites Tone detection AI writing assistant Plagiarism and AI detection Team style guides	AI humaniser AI detector Human typer Image and video detectors API

Pros and cons

Attribute	Grammarly	Undetectable AI
Pros	Works live in almost every app you type in Free plan is useful for everyday spelling and grammar Tone feedback helps with tricky messages Team style guides keep company writing consistent Yearly Pro price is reasonable for daily use	Simple: paste, pick a level, rewrite Built-in detector shows how text might score Cheap on yearly plans API for bulk rewriting Refund on humanised text that gets flagged
Cons	Free plan no longer includes sentence rewrites and caps AI prompts at 100 a month Monthly billing costs more than double the yearly rate Accepting every suggestion can strip your own voice Strongest in English only Withdrew its "Expert Review" feature in 2026 after a lawsuit over using authors' identities	No guarantee text will pass detectors Rewrites can read awkwardly or change your meaning Using it to hide AI use can break school or client rules Free trial is only 250 words Its marketing promises more than any humaniser can deliver

Who each one is for

Attribute	Grammarly	Undetectable AI
Best for	Proofreading emails and documents as you type Checking tone before a tricky message goes out Writing at work in English as a second language Keeping a team's writing style consistent Plagiarism checks on content	Making AI drafts sound less robotic Seeing how detectors might score your text Rewriting at a set reading level Bulk rewriting through the API
You'll find it used by	Office staff Sales and support teams Non-native English writers Students Marketers	Content marketers Bloggers Freelance writers SEO agencies Students

Questions people ask

Which is better, Grammarly or Undetectable AI?

Grammarly scores highest overall in our ratings (Grammarly 4.3/5 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. Undetectable AI is best for Making AI drafts sound less robotic and seeing how detectors might score your text.

Which is cheaper, Grammarly or Undetectable AI?

Grammarly: There's a free plan, and paid plans start at $12/member/mo. Undetectable AI: There's a free plan, and paid plans start at $0.

Which is easier to use, Grammarly 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.

Ratings are our own, from using each tool, across ease of use, features, output quality, value for money, speed & reliability.

Swap in another tool

More tools from Writing & Translation in the library.