LanguageTool alternatives: 7 open-source picks
LanguageTool costs $5.47/mo — $65.64 a year. These 7 alternatives replace it for $0, led by Harper, Writing Tools and WritingTool. All 7 are open source. License, stars and last commit checked by hand on 2026-08-29. No trials, no crippled tiers.
A fast English grammar checker that stays on your device and mostly keeps its opinions to itself.
Select text anywhere, hit a hotkey, and fix, rewrite, summarize, or obey a custom instruction without opening another tab.
licenseGPL-3.0
runson your machine
installUse the portable Windows ZIP or macOS DMG; Linux currently runs from source
enginesGemini, native Ollama and any OpenAI-compatible cloud or local endpoint on Windows/Linux; the macOS port also supports OpenAI, Anthropic, Mistral, OpenRouter, Gemini, MLX and Ollama
dataAPI keys and configuration stay on the device; the app does not retain writing or logs, and selected text goes only to the chosen cloud provider unless a local model is used
the catch vs LanguageToolIt relies on generative models for corrections, so checks are less deterministic and its multilingual grammar rules and explanations are much thinner than LanguageTool's.
setupYou must supply an API key or install a local model; macOS needs Accessibility permissions, while Linux installation and Wayland support remain rough
facts verified 2026-08-14
A LibreOffice extension with long-document checks, style statistics, profiles, and local AI; installing Java is the cover charge.
licenseLGPL-2.1
runson your machine
installInstall LibreOffice 24.2+, Java 17+, then add the downloaded .oxt LibreOffice extension
enginesLanguageTool rules locally; optional AI rewriting through an OpenAI-compatible API, with local endpoints such as LocalAI specifically supported
dataChecks, profiles and cached document-analysis data run on the local computer; document text is sent away only when a remote LanguageTool or configured AI endpoint is used
the catch vs LanguageToolIts LanguageTool-based checks are strong inside LibreOffice, but browser, email, mobile, and cross-application coverage are much weaker than LanguageTool's.
setupJava 17 and a recent LibreOffice are mandatory, and users must manually install and approve the extension
facts verified 2026-08-14
One-command local runner for Llama, Qwen, DeepSeek, Gemma and other open models with an API
licenseMIT
runsyour server
setupnot verified by us yet — check the repo README
facts verified 2026-08-29
Polished multi-model AI chat UI with plugins, knowledge base, and one-click deploy.
licenseApache-2.0
runsyour server
setupnot verified by us yet — check the repo README
facts verified 2026-08-29
One chat UI for every provider — OpenAI, Anthropic, Google, local models — with agents, search, and per-user keys.
licenseMIT
runsyour server
setupnot verified by us yet — check the repo README
facts verified 2026-08-29
Grammar, style and spell checker for 30+ languages; run the server locally and keep your prose private.
licenseLGPL-2.1
runsyour server
setupnot verified by us yet — check the repo README
facts verified 2026-08-29
What each one is, in full: Ollama · Lobe Chat · LibreChat
last updated 2026-08-29 · no votes, no pay-to-list · just what's real
how to choose a LanguageTool alternative
Easiest to get running
Harper — a one-click install, no server to maintain.
Most proven
Ollama, with 178,000 GitHub stars — the largest community of the 7, which usually means more answers when something breaks.
Runs on your own machine, no server
Writing Tools — nothing to host, your data stays on your disk.
Works on your phone
Harper has a mobile app.
what you give up by leaving LanguageTool
- premium rule set
- hosted server convenience
- browser extension premium flows
- team/admin options
- support
None of the picks above covers all of it. The full verdict says which gaps matter.
LanguageTool alternatives at a glance
| tool | license | running it | platforms | stars | active |
|---|---|---|---|---|---|
| Harper | open source | one-click install | macos, android, browser-extension | 14,200 | 2026-08 |
| Writing Tools | GPL-3.0 | one-click install | macos, windows | 2,400 | 2026-05 |
| WritingTool | LGPL-2.1 | one-click install | macos, windows, linux | 65 | 2026-07 |
| Ollama | MIT | one-click install | self-hosted, web | 178,000 | 2026-08 |
| Lobe Chat | Apache-2.0 | one-click install | self-hosted, web | 65,000 | 2026-08 |
| LibreChat | MIT | one-click install | self-hosted, web | 28,000 | 2026-08 |
| LanguageTool | LGPL-2.1 | docker to self-host | self-hosted, web | 13,000 | 2026-08 |
why people still pay for LanguageTool
They pay for hosted convenience, premium rules, and cross-device setup. If none of that applies to you, any pick above saves $65.64 a year.
questions about switching from LanguageTool
Is there an open-source alternative to LanguageTool?
Yes: Harper, Writing Tools, WritingTool and 4 more. Every tool on this page is open source: no trials, no crippled tiers.
Can open source really replace LanguageTool?
Our verdict is YES. Ollama (178k stars), Lobe Chat (65k stars), LibreChat (28k stars) are mature open-source replacements for LanguageTool — self-host in one command and stop paying $5.47/mo. The full verdict, and what you give up by switching, is at caniopensourceit.online/languagetool.
What is the easiest open-source LanguageTool alternative to set up?
Harper — a one-click install, no server to maintain.
What is the most popular open-source LanguageTool alternative?
By GitHub stars, Ollama (178,000). Lobe Chat is next with 65,000.
