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

Dayflow is a privacy-focused productivity tool that records screen activity locally and analyzes it with on-device AI. It captures screen frames at one frame per second, stores everything in a local database, and processes all analysis entirely on the machine to keep data private. The system builds a searchable timeline of work activity and enables natural-language queries about past screen time. The tool distinguishes itself by offering runtime switching between local AI models and cloud providers, allowing users to balance accuracy, privacy, and performance. It automatically runs AI inferen

HeliBoard is a customizable Android keyboard that provides offline predictive text and a privacy-focused virtual interface. It operates entirely without internet permissions to ensure that all keystrokes and user data remain on the device. The keyboard features gesture-based glide typing and allows for the integration of external dictionaries to improve autocorrect and symbol search. It supports simultaneous multilingual input, enabling users to enter text in several different languages within a single session. Users can personalize the experience through editable text-file layout configurat

AionUi is an AI agent orchestration platform designed to manage and coordinate multiple autonomous assistants within a local environment. It functions as a framework for executing background processes and scheduled tasks that operate independently of the user interface, ensuring that automated workflows continue to run without manual oversight. The platform distinguishes itself through a local-first approach to document generation and file manipulation, allowing users to create and modify office files directly on their hardware to maintain data privacy. It supports parallel agent execution, e

h2oGPT is a self-hosted platform designed for running large language models and executing retrieval-augmented generation workflows locally. It provides a comprehensive web interface that allows users to index private document collections into searchable databases, enabling context-aware question answering and summarization without exposing sensitive data to external services. The platform distinguishes itself by offering a modular architecture that supports both local model execution and connections to external inference servers. It facilitates the development of autonomous agents capable of

Hermes-webui is a self-hosted AI orchestrator and web interface for managing autonomous agents. It serves as a multi-provider gateway that connects cloud and local large language models, providing a central hub to execute scheduled background jobs, run shell commands, and manage agent memory on private hardware. The system distinguishes itself through a persistent memory manager that utilizes knowledge graphs and markdown files for long-term context across sessions. It features a model context protocol host for extending agent capabilities with standardized tools and supports the orchestratio