{
    "products": [
        {
            "slug": "harper",
            "name": "Harper",
            "kind": "app",
            "website": "https://writewithharper.com/",
            "page": "https://listme.name/software/harper",
            "tagline": "Open-source grammar checker that runs on your own device",
            "summary": "Harper is a free, open-source grammar and spell checker that runs locally on your device. It has browser extensions for Chrome, Edge and Firefox, and plugins for VS Code, Obsidian and Neovim. The code is licensed under Apache-2.0 and published on GitHub.",
            "platforms": [
                "macos",
                "browser-extension"
            ],
            "pricing": "open-source",
            "price_note": "Free and open source under Apache-2.0; no paid tier listed",
            "free_to_use": true,
            "open_source": true,
            "license": "Apache-2.0",
            "source": "https://github.com/Automattic/harper",
            "strengths": [
                "Free and open source under Apache-2.0",
                "Checks run on your device, with no telemetry",
                "Fast enough for live checks as you type"
            ],
            "limits": [
                "Desktop app is listed for macOS only",
                "No AI rewriting or tone suggestions"
            ],
            "checked": "2026-10-10",
            "connected_to_publisher": false,
            "overview": "Harper checks spelling, capitalization, awkward phrasing and broken grammar, and it covers US, UK, Canadian, Australian and Indian English. The project says every check runs on the device, with no cloud round-trip and no telemetry. It is written in Rust, which keeps checks fast enough to run as you type.\n\nHarper is distributed as a macOS desktop app, as Chrome, Edge and Firefox extensions, and as plugins for VS Code, Obsidian, Neovim and Zed. Its source is on GitHub under Apache-2.0. The project says no language model runs in the loop, so Harper does not offer AI rewrites or tone suggestions. The desktop app is listed for macOS only."
        },
        {
            "slug": "languagetool",
            "name": "LanguageTool",
            "kind": "app",
            "website": "https://languagetool.org/",
            "page": "https://listme.name/software/languagetool",
            "tagline": "Open-source grammar, spelling and style checker for many languages",
            "summary": "LanguageTool is a grammar, spelling and style checker for dozens of languages, with browser add-ons, Office plugins and a Premium tier. Its core is open-source software under the LGPL 2.1 license.",
            "platforms": [
                "web",
                "windows",
                "macos",
                "browser-extension"
            ],
            "pricing": "freemium",
            "price_note": "Free grammar checking; Premium adds unlimited paraphrasing and more features",
            "free_to_use": true,
            "open_source": true,
            "license": "LGPL-2.1",
            "source": "https://github.com/languagetool-org/languagetool",
            "strengths": [
                "Core source code on GitHub under LGPL 2.1",
                "Browser add-ons and Office plugins",
                "Covers dozens of languages"
            ],
            "limits": [
                "Paraphrasing is limited in the free version",
                "Less focused on generating new text than AI-first tools"
            ],
            "checked": "2026-10-10",
            "connected_to_publisher": false,
            "overview": "LanguageTool checks grammar, spelling, punctuation and style in its web editor and through browser add-ons for Chrome, Edge, Firefox and Opera. It also has Windows and macOS apps, add-ons for Gmail and Outlook, plugins for Google Docs, Word and LibreOffice, and a proofreading API for businesses.\n\nThe core checker is free to use, and Premium adds features such as unlimited paraphrasing. The core source is on GitHub under LGPL 2.1 or later, which places it among the open-source options in this category. Its focus is correctness and style checking across many languages rather than generating new text, so it complements an AI writing tool more than it replaces one."
        }
    ],
    "differences": [
        "Only LanguageTool runs on Windows.",
        "Only LanguageTool runs on Web.",
        "Harper: free and open source. LanguageTool: free plan, paid upgrades."
    ],
    "shared_rankings": [
        {
            "list": "grammar-and-proofreading-tools",
            "name": "Grammar and proofreading tools",
            "page": "https://listme.name/best/grammar-and-proofreading-tools",
            "of": 10,
            "results": [
                {
                    "product": "harper",
                    "rank": 3,
                    "score": 89.5,
                    "verdict": "Free, Apache-2.0 open source, with checks that run on your device. It covers grammar and spelling only, and its desktop app is listed for macOS.",
                    "best_for": "Private, free grammar checks on your own device",
                    "spec": {
                        "where": "On your device, in browsers and editors",
                        "rewrites": "None; no AI model in the loop",
                        "style": "Grammar and spelling only"
                    }
                },
                {
                    "product": "languagetool",
                    "rank": 2,
                    "score": 91,
                    "verdict": "Open-source core under LGPL-2.1, with browser add-ons, Office plugins and many languages. Free checking is solid, but paraphrasing is limited on the free tier.",
                    "best_for": "Open-source checking in many languages",
                    "spec": {
                        "where": "Browser add-ons, desktop apps and Office plugins",
                        "rewrites": "Paraphrasing, limited on the free plan",
                        "style": "Style checking in many languages"
                    }
                }
            ]
        }
    ],
    "ranks_higher_in_closest_shared_list": "languagetool",
    "page": "https://listme.name/compare/harper-vs-languagetool",
    "json": "https://listme.name/api/v1/compare/harper-vs-languagetool.json",
    "notes": [
        "Scores are editorial and only comparable inside one list. Products with connected_to_publisher true receive a disclosed ranking lift: https://listme.name/methodology"
    ],
    "source": "https://listme.name",
    "license": "Free to read and cite with attribution to listme.name.",
    "docs": "https://listme.name/developers"
}