LanguageTool vs Lex

LanguageTool 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.

LanguageTool

LanguageTool operates as a browser add-on, office plugin, and standalone editor, catching grammar, spelling, punctuation, and style errors wherever text is typed. The paraphrasing tool lets you rewrite sentences on the spot without switching to a separate application. The API gives development teams a way to pipe checks directly into internal tools or content pipelines. The ceiling appears when you need deep style enforcement: custom brand-voice rules and advanced style guidance are paid-only features, so free-tier users get error correction but not the consistency layer that brand and comms teams actually need.

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	LanguageTool	Lex
Pricing	Paid	Paid
Price	$24.90/month	—
Free trial	No	No
Open source	No	No
Has API	Yes	No
Self-hosted option	No	No
Platforms	Web, Chrome, Edge, Firefox, Safari, Opera, Gmail, Apple Mail, Thunderbird, Google Docs, Word, Apple Pages, LibreOffice, macOS, Windows	Web, iOS
Pros	Checks text in 30+ languages with automatic language detection, so multilingual teams avoid manual mode-switching when documents mix languages. Add-ons cover every major browser and office suite — Chrome, Word, Google Docs, Gmail, LibreOffice among them — which means writers get corrections inside the tools they already use instead of copying text into a separate checker. A Proofreading API is available for developer integration, so teams can embed grammar checks directly into content pipelines or internal tools without building their own NLP layer. The browser add-on processes text without storing it locally, the vendor states, so teams with basic data-handling requirements can deploy it without a dedicated privacy review of client-side storage. A personal dictionary and writing statistics are available in the editor, so writers can track error patterns over time and build vocabulary the tool does not flag incorrectly.	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	Advanced style suggestions, brand voice consistency rules, and unlimited paraphrasing are paid-only features. A comms or content team that deploys the free tier expecting style enforcement will find the correction layer stops at grammar and basic spelling — they either upgrade or manually enforce style in a separate pass. There is no self-hosted option and no downloadable binary. Organizations under strict data-residency requirements or internal security policies that prohibit sending document text to external servers cannot use LanguageTool at all, and will move to an on-premise alternative or build their own correction layer. The paraphrasing tool has a usage cap on the free tier. Writers who lean on it for rewriting multiple drafts per day hit the ceiling mid-session and either stop or upgrade — there is no graceful degradation that preserves partial functionality. API access at production volume is a paid-only feature. A team that prototypes on the free API and plans to scale will discover the rate limits before launch, requiring a billing decision they did not budget for at the start of the project.	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

Only LanguageTool exposes a public API. Choose based on which difference matters most for your workflow.

Frequently asked questions

What is the difference between LanguageTool and Lex?

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

Is LanguageTool 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.