Open-Source Alternatives to Grammarly

Harper is a local English linter and grammar checker designed as an IDE writing assistant. It operates as a language server that provides real-time spelling and grammar analysis for markdown and code comments, processing all linguistic data on the local device to ensure privacy and eliminate cloud dependencies. The tool is specialized for technical documentation, featuring the ability to identify and ignore text within code fences and inline blocks to prevent false positives. It allows for personalized configuration through custom dictionaries and the use of suppression comments to exclude sp

LanguageTool is a multilingual grammar and style checking engine designed to detect spelling, grammar, and writing errors across multiple languages. It provides automated proofreading capabilities that can be deployed as a self-hosted server or executed as a standalone local desktop application. The project distinguishes itself through a flexible rule development framework, allowing linguistic patterns to be defined via XML or implemented as custom Java classes. It utilizes n-gram frequency modeling for confused word detection and supports neural word embeddings to improve disambiguation betw

Proselint is a prose linter and rule-based text analyzer designed to identify stylistic errors, clichés, and jargon in written text. It scans documents against a curated registry of linguistic and typographic rules to maintain professional editorial standards and improve writing quality. The project functions as a command line text processor, a programmable analysis library, and a git pre-commit hook. Its modular architecture allows the core engine to be embedded into other applications, exposed via a REST API, or integrated into text editors. The tool supports recursive directory traversal

textlint is the pluggable linter for natural language text.

Scramble is an artificial intelligence-powered browser extension designed to assist with text processing, editing, and writing directly within web pages. It functions as a text editor that allows users to highlight content on any webpage and transform it through summarization, correction, or rewriting. The tool distinguishes itself by providing a provider-agnostic abstraction layer, enabling users to connect to various local or cloud-based language models by configuring their own authentication keys and endpoints. It supports custom prompt engineering, allowing users to define and save person