onsystem
onsystem is an MCP server that keeps coding agents on your design system for React and shadcn/ui code, for design-system and platform teams.
What it is good for
- Stopping coding agents from writing hardcoded colors and spacing
- Catching made-up component names and props in generated UI code
- Checking UI code changes in pull requests against a design system
- Keeping every app in a monorepo on the same design system
At a glance
- Who it is for
- Setup
- Guided command-line setup
Level 4 of 5. You copy and paste commands into a terminal by following the instructions. Comfortable territory for vibe coders.
- Cost
- Free and open source
- Type
- MCP server or connector
- Tasks
- Works with
- Claude Code, Cursor, Codex CLI, Gemini CLI, Claude Desktop, GitHub Actions
Momentum
- Rank this week
- Not ranked yet
- Best rank
- None yet
- GitHub stars
- 165
GitHub numbers as of Nov 2, 2026. Updated weekly.
Official links
Setup steps are on the official pages. We do not repeat them here, since they change.
Questions
- Is onsystem free?
- Yes. It is free and open source (MIT license).
- Do I need to know how to code to use onsystem?
- You do not need to write code, but setup means copying and pasting commands into a terminal by following its instructions.
- What does onsystem work with?
- According to its own documentation, it works with Claude Code, Cursor, Codex CLI, Gemini CLI, Claude Desktop, and GitHub Actions.
- What is onsystem good for?
- Stopping coding agents from writing hardcoded colors and spacing, catching made-up component names and props in generated UI code, checking UI code changes in pull requests against a design system, and keeping every app in a monorepo on the same design system.
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