Cotypist vs Lex

Cotypist and Lex are both grammar & style checkers tracked by AIDiveForge. Below is a side-by-side comparison of pricing, capabilities, platforms, and ownership — sourced from each tool's live website and verified before publishing.

Cotypist

Cotypist sits in the macOS menu bar and surfaces word-completion suggestions as you type, accepted with a Tab keystroke, across whichever apps you have open. The differentiating mechanic is per-app instruction profiles: you teach it one voice for client emails, a different register for pull-request descriptions, and it holds those rules separately per application. On-device processing keeps your keystrokes off external servers. The free tier caps daily output at 100 words — a ceiling that arrives fast for anyone with real writing volume. No API, no Windows build, no self-hosting path exists.

Lex

Lex is a browser-based collaborative writing editor from Lex, Inc., aimed at writers who want AI feedback woven into the drafting process rather than pasted in from a separate window. The AI Feedback feature lets you ask for critique, rewrites, or brainstorming directly against your draft, while commands surface options like word suggestions and idea lists without leaving the keyboard. Versions let you test a rewrite without nuking what you already have — a small feature that matters more than it sounds the third time you regret an edit. Live collaboration and mobile web access work link-first, no app required. Track Changes is listed as coming soon, which is a gap that teams used to Google Docs comment workflows will feel immediately.

Attribute	Cotypist	Lex
Pricing	Paid	Paid
Price	$6/mo or $9/mo	—
Free trial	30 days	No
Open source	No	No
Has API	No	No
Self-hosted option	No	No
Platforms	macOS	Web, iOS
Pros	Per-app instruction profiles let you maintain a different writing register for each application, so client emails, Slack messages, and code comments each get the voice you set without manual switching. On-device processing means your keystrokes and draft content are not transmitted to external servers, which matters for anyone working with confidential documents or under data-handling obligations. Tab-to-accept inline completions work inside whichever Mac app has focus, so you never break flow by switching to a separate chat window or sidebar. Multi-Mac profile sync at the paid tier means your per-app voice configuration carries across machines, avoiding the tedious work of reconfiguring from scratch on a second device.	AI feedback runs against your actual draft in context, so you get critique and rewrites without copying text into a separate chat window and losing the thread of the edit. Versions let you test a rewrite without overwriting your original, which means you stop treating undo history as a safety net and start making bolder edits. Link-based collaboration requires no app install from collaborators, so sharing a draft for real-time review does not become an onboarding task. Mobile web access means the document is reachable from any device without a native app, so you are not locked to a desktop to review feedback on the go. Keyboard-driven commands for word suggestions and idea generation keep your hands off the mouse during drafting flow, which matters when momentum is the thing you are protecting.
Cons	The free tier's 100-words-per-day cap cuts off mid-session for anyone with real writing volume — a journalist drafting a single article, a developer writing commit messages all morning, or a support agent handling a ticket queue will exhaust it before noon and face a choice between upgrading or stopping. There is no Windows version, no Linux path, and no browser extension, so any team that runs a mixed OS environment cannot standardize on this tool — the realistic next step is a browser-based assistant like a Chrome extension that works across platforms. No API means completions cannot be scripted into a build pipeline, a CMS workflow, or any automated process — teams that want completion suggestions integrated into custom tooling have no integration surface and will need a provider that exposes one. The passive suggestion model offers no ability to run multi-step tasks, draft from a prompt, or trigger actions — writers who need to generate a full first draft rather than complete sentences in progress will find the interaction model too narrow and reach for a dedicated generation tool.	Track Changes is not yet available — listed as coming soon on the vendor page. Teams that rely on marked-up revision trails (academic editors, legal reviewers, anyone who needs a documented record of what changed and who changed it) cannot use Lex as their primary review tool and will route documents back to Google Docs or Word for that stage. There is no API and no self-hosted option. Any team building a writing-adjacent product, automating document processing, or operating under data-residency requirements hits a hard wall here — at which point they move to an editor they can control or integrate, not a closed SaaS surface. The AI feedback and commands are chat- and shortcut-driven rather than structured. For writers who need rubric-based feedback (grade this against APA style, check for passive voice across the document) rather than conversational suggestions, the tool does not provide that systematically — and those writers end up maintaining a separate grammar or style checker alongside Lex.

Bottom line

Cotypist and Lex are closely matched on pricing model, openness, and API availability — pick by feature set and platform support in the table above.

Frequently asked questions

What is the difference between Cotypist and Lex?

Cotypist is Paid, while Lex is Paid. Compare pricing, free trial, API, platforms, and pros/cons in the table above on AIDiveForge.

Is Cotypist better than Lex?

It depends on your workflow. Use the side-by-side attributes (pricing, open source, API, self-hosted, platforms) to decide. AIDiveForge does not rank a universal winner — we publish verified facts so you can choose.

Cotypist vs Lex: which should I pick?

Pick Cotypist if its pricing model, openness, or platform fit matches your constraints; pick Lex otherwise. Check free-trial availability on each listing if you want to test before committing.

Comparison data is sourced and verified by the AIDiveForge data pipeline. AIDiveForge is editorially independent.