CoWriter AI vs Grammarly

Two fact sheets from our own research, side by side — pricing, platforms, API access and status re-checked by us rather than quoted from the vendors.

The short answer

Cheaper paid plan: CoWriter AI — $11.99/mo vs $12/mo for Grammarly
Free plan: Only Grammarly (CoWriter AI has paid plans only)
Higher Trust score: Grammarly — 94 vs 87 for CoWriter AI
Best fit: CoWriter AI: Students juggling citation formats across assignments · Grammarly: Anyone writing in a browser, Word or email who wants corrections in place
Platforms: CoWriter AI: Web · Grammarly: Web, Chrome extension, Windows, macOS, iOS, Android

From our own records as of each tool's last check. Anything we have not confirmed is left out rather than guessed. How we verify

CoWriter AIStudent writing workspace with drafting, citation generators, plagiarism checks and AI-detection evasion.

GrammarlyGrammar, tone and rewriting help inside every app

Side by side

Fact	CoWriter AI	Grammarly
Category	Essay & Assignment Help	Grammar & Proofreading
Pricing model	Paid	Freemium
Starts at	$11.99/mo	$12/mo
Trust score	87 / 100	94 / 100
Platforms	Web	Web, Chrome extension, Windows, macOS, iOS, Android
Company	Protonlabs Technology Inc	Superhuman
Launched	—	2009
Last verified	Oct 16, 2026	Oct 16, 2026

What our research says

CoWriter AI

Bundles the things a student actually opens five tabs for — drafting, citations, plagiarism check — into one $11.99 workspace, and the free citation generators are useful on their own. The terms are where this turns sour: no refunds under any circumstances and an explicit request that you waive chargeback rights. That, plus the AI-detection-evasion pitch, makes it a tool to enter with eyes open.

Pros

Citation generators for APA, MLA, Chicago, IEEE, Harvard, Vancouver, CSE and more
Plagiarism detection and grammar checking alongside drafting
Free standalone tools usable without a subscription
Named legal entity, ProtonLabs Technology Inc, in the footer

Cons

Terms state all sales are final with no refunds, credits or pro-rata reimbursement
Terms ask users to waive the right to dispute or charge back any transaction
Markets AI-detection evasion, which conflicts with most academic integrity policies
No country, address or API published

Grammarly

Still the default for catching mistakes inside other people's software, but the free tier has quietly become an AI-prompt meter and the honest price is $30 unless you commit to a full year.

Pros

Runs inside the apps people already write in rather than as a separate editor
Free tier still covers spelling, grammar and tone detection with no time limit
Pro folds in plagiarism and AI-text detection that rivals charge for separately

Cons

The $12 headline is the annual rate; paying monthly costs $30
Free AI allowance is 100 prompts a month and depletes quickly
No public API, so it cannot be embedded in another product
Enterprise pricing is not published anywhere on the site

Which one fits

Choose CoWriter AI if you need

Students juggling citation formats across assignments
Anyone who wants drafting and plagiarism checking in one place
Users who want free standalone citation generators

Choose Grammarly if you need

Anyone writing in a browser, Word or email who wants corrections in place
Teams enforcing a house style guide across people who are not writers
Non-native English speakers who want fluency rewrites, not just error flags