Quill

Quill is a free and open-source writing application for macOS 26 or later, combining a Markdown editor with built-in AI editing from multiple model co-writers. It lets users edit drafts by voice or text, with revisions made directly in place. - Edits drafts in place using selected AI co-writers, such as Claude Code or Codex - Supports voice or typed editing requests using keyboard shortcuts - Offers multi-model editing by stacking responses from multiple AI agents for comparison - Stores notes as plain .md files compatible with Obsidian - Reads and applies user style rules from a Voice.md file before every edit - Connect supported agent sign-ins or your own compatible API endpoint; provider charges and subscriptions are separate Quill is available at no cost, distributed under the Apache 2.0 license, and requires macOS 26 or later. Users must have or set up supported AI agent accounts to enable co-writer editing capabilities.