arctic-shift-mcp

A zero-auth, drop-in Reddit MCP server backed by the Arctic Shift archive.

Most Reddit MCP servers break because they hit Reddit's live API/pages, which now blocks data-center IPs and/or requires an authenticated app. This server reads from Arctic Shift instead — a continuously-updated public archive of Reddit — so search and read work with no Reddit login at all. Posting, replying, and voting are available too, but only switch on when you supply your own Reddit API credentials.

• ✅ Search & read with no auth — posts, comments, users, subreddits
• ✅ Near-live data — the archive trails real Reddit by minutes, not days
• ✅ Write opt-in — submit_post, reply, vote, edit_content, delete_content register only when credentials are set
• ✅ Familiar tool names — drop it in where a broken Reddit MCP used to be

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Quick start

Claude Code

claude mcp add reddit -- npx -y github:Kevsosmooth/arctic-shift-mcp

Any MCP client (Claude Desktop, Cursor, Windsurf, …)

Add to your MCP config (.mcp.json, claude_desktop_config.json, Cursor settings, etc.):

{
  "mcpServers": {
    "reddit": {
      "command": "npx",
      "args": ["-y", "github:Kevsosmooth/arctic-shift-mcp"]
    }
  }
}

That's the full read-only setup. No keys, no account.

Once published to npm you can swap github:Kevsosmooth/arctic-shift-mcp for just arctic-shift-mcp.

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Enabling write mode (optional)

Writing to Reddit requires your own Reddit account + API app — there's no way around that, and it's intentional: the read side stays auth-free for everyone, and only you can post as you.

1. Go to https://www.reddit.com/prefs/apps → create another app…
2. Choose script, set the redirect URI to http://localhost:8080 (unused for password grant).
3. Note the client id (under the app name) and secret.
4. Add the credentials to the server's env:

{
  "mcpServers": {
    "reddit": {
      "command": "npx",
      "args": ["-y", "github:Kevsosmooth/arctic-shift-mcp"],
      "env": {
        "REDDIT_CLIENT_ID": "your_client_id",
        "REDDIT_CLIENT_SECRET": "your_client_secret",
        "REDDIT_USERNAME": "your_username",
        "REDDIT_PASSWORD": "your_password"
      }
    }
  }
}

Prefer not to store a password? Use a refresh token instead:

"env": {
  "REDDIT_CLIENT_ID": "your_client_id",
  "REDDIT_CLIENT_SECRET": "your_client_secret",
  "REDDIT_REFRESH_TOKEN": "your_refresh_token"
}

When valid credentials are present the server logs write mode ENABLED on startup and exposes the five write tools. Otherwise it runs read-only.

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Configuration

Env var	Required	Default	Purpose
REDDIT_CLIENT_ID	for writes	—	Reddit "script" app client id
REDDIT_CLIENT_SECRET	for writes	—	Reddit app secret
REDDIT_USERNAME	for writes*	—	Reddit account username (password grant)
REDDIT_PASSWORD	for writes*	—	Reddit account password (password grant)
REDDIT_REFRESH_TOKEN	for writes*	—	Alternative to username/password
ARCTIC_SHIFT_USER_AGENT	no	arctic-shift-mcp/0.1 (+repo url)	User-Agent sent to Arctic Shift & Reddit
ARCTIC_SHIFT_BASE	no	https://arctic-shift.photon-reddit.com/api	Override the archive endpoint

* Writes need an app and a login: either USERNAME+PASSWORD, or REFRESH_TOKEN.

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Tools

Read (always available)

Tool	Description
search_reddit	Search posts by query (keyword), subreddit, and/or author. A keyword needs a subreddit or author.
get_subreddit_posts	Recent posts in a subreddit, chronologically.
get_reddit_post	One post with full body, by id / t3_… / URL.
get_post_comments	A post's comments (flat + chronological; parent_id/link_id rebuild threads).
get_subreddit_info	Subreddit metadata + rules.
get_user_posts	Posts by a user.
get_user_comments	Comments by a user.

Write (only when credentials are set)

Tool	Description
submit_post	Create a self/text or link post.
reply	Comment on a post (t3_…) or reply to a comment (t1_…).
vote	up / down / clear on a post or comment.
edit_content	Edit your own self-post or comment.
delete_content	Delete your own post or comment.

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Limitations

• Read is an archive. It's continuously updated and usually only minutes behind live, but the very newest items (last few minutes on busy subs) may not be indexed yet, and live vote counts drift.
• Listing is by time, not score. Arctic Shift sorts by creation date, so get_subreddit_posts is chronological — there's no "top of all time" sort.
• Writes always need your own Reddit app + login. Read mode can never post; that's by design.

How it works

Read tools call the Arctic Shift REST API (/posts/search, /comments/search, /posts/ids, /subreddits/search, …). Write tools call Reddit's OAuth API (oauth.reddit.com) using a token minted from your credentials and cached in memory until just before expiry. Nothing is written to disk.

Responsible use

This project leans on Arctic Shift, a free service run by one developer. Please be a good citizen:

• Don't hammer it on every page-load of a busy app — cache results in your own store and refresh on a schedule.
• Keep a descriptive ARCTIC_SHIFT_USER_AGENT.
• Respect its rate limit (the server surfaces HTTP 429 clearly so you can back off).
• To remove your own Reddit data from the archive, use Arctic Shift's removal form.

Huge thanks to Arthur Heitmann for keeping Reddit data accessible.

Development

npm install        # installs deps and builds (via prepare)
npm run build      # tsc -> dist/
npm test           # unit tests (node --test)
npm run dev        # watch mode

License

MIT © Kevsosmooth