Crossbar

Give your AI agent your X (Twitter) account. No API key, no developer account, no API bill.

Install · What you can ask · Skills & agents · Tools · CLI · How it works

Crossbar turns your own X account into an MCP server and a CLI. Claude Code, Claude Desktop, Cursor, VS Code, Codex and Gemini CLI get 27 tools to read your timeline, search, read threads, check mentions and DMs, and post, reply, quote, like, repost, bookmark, follow, mute, block and DM, all as you.

It sends the same requests x.com's web app sends, with the session from the browser you're already signed in to, from your own machine. Built on api-anything.

you>    what's new from people I follow? reply to the best one with "great thread"
claude> [x_home_timeline feed=following] ... [x_reply post=1985... text="great thread"]
        ✓ replied  https://x.com/i/status/1985...

Why Crossbar

Related MCP server: byob

⚡ Install

Needs Node 22.13+ and a Chromium browser (Chrome, Edge, Brave, Arc, Vivaldi or Chromium) signed in to x.com.

One line, any OS:

npm install -g github:prantikmedhi/crossbar && crossbar setup && crossbar login

That installs the crossbar command, connects the MCP server to every agent it finds on your machine, and imports your x.com session from your browser. Restart your agent and ask "what's on my X timeline?"

Claude Code plugin (skills + agents included)

/plugin marketplace add prantikmedhi/crossbar
/plugin install crossbar@crossbar

The plugin brings the MCP server (run through npx, nothing else to install), three skills and three subagents. Run npx -y github:prantikmedhi/crossbar login once to sign in.

From a clone, macOS / Linux

git clone https://github.com/prantikmedhi/crossbar && cd crossbar && ./install.sh

From a clone, Windows (PowerShell)

git clone https://github.com/prantikmedhi/crossbar; cd crossbar; powershell -ExecutionPolicy Bypass -File .\install.ps1

Without installing anything globally: point any MCP client at:

{ "mcpServers": { "crossbar": { "command": "npx", "args": ["-y", "github:prantikmedhi/crossbar", "mcp"] } } }

Read-only agent (no write tools at all):

crossbar setup --read-only

Print the config for any client, to add it by hand:

crossbar mcp --print-config

crossbar setup puts the X spec in ~/.api-anything/sites/x.json and connects the MCP server with claude mcp add, codex mcp add, gemini mcp add and code --add-mcp, and edits Claude Desktop's and Cursor's JSON configs. It backs up each config to *.bak-crossbar before the first edit. --dry-run shows what it would change.

💬 What you can ask

Once it's connected, just talk to your agent:

• "Summarize my Following timeline from today. Skip the memes."

• "What are people on X saying about Claude Code plugins this week? Give me the best 5 takes with links."

• "Check my mentions and DMs. What needs a reply?"

• "Read this thread and draft a reply that pushes back on point 3: https://x.com/..."

• "Turn this changelog into a post in my voice. Show me three options first."

• "Who are the most active accounts replying to @anthropicai about MCP?"

• "Bookmark the top post on from:nasa moon and like it."

Writes are marked as writes (⚠ for destructive ones) in MCP, so your client asks before it posts.

🧠 Skills & agents

Crossbar ships ready-made know-how for agents, in skills/ and agents/. The Claude Code plugin installs them for you. For other agents that read Agent Skills, copy the skills/ folders into that agent's skills directory.

🔑 Sign in and out

The session stays in ~/.api-anything/ on your machine (0600) and never leaves it. It's the same session as your browser's: signing out of X in the browser signs Crossbar out too. Then run crossbar login again.

🧰 27 MCP tools

Posts accept an id or a URL. Users accept @handle, a profile URL or a numeric id. Lists are paged: pass next_cursor back as cursor.

⌨️ CLI

The same account, from your terminal:

crossbar home --following
crossbar search "from:nasa moon" --mode latest
crossbar read https://x.com/jack/status/20
crossbar profile @nasa
crossbar posts @nasa --replies
crossbar post "Hello from Crossbar"
crossbar reply 1985000000000000000 "Agreed"
crossbar like <post> --undo
crossbar follow @nasa
crossbar dm @friend "hey"
crossbar dms
crossbar notifications

Run crossbar --help for every command. Add --json for the raw answer, which is handy for scripts and jq.

🔧 How it works

Crossbar's spec/x.json describes 36 X operations in api-anything's format: X's GraphQL and v1.1 endpoints, with cookie:ct0 → x-csrf-token and your cookies filled in per call. The spec holds no credentials. Each call goes through api-anything's tier ladder:

1. Plain HTTPS from Node (fast, about 0.2–1 s).

2. If X blocks that: fetch from inside a real browser page.

3. If X needs its own per-request signature (x-client-transaction-id): Crossbar runs the action in x.com itself in your browser profile. For a post, it opens the composer, types your text and clicks Post. Slower, but it works whatever X requires.

When X changes things

When X rotates a GraphQL queryId (it does every few weeks), the first call gets a 404. api-anything finds the new id in x.com's scripts, replays the call and saves the fix, without a browser. When X changes the features it requires, api-anything re-learns the request from x.com in your browser. crossbar status shows each operation's health. If a heal goes wrong:

npx api-anything revert x <op>

crossbar install --force

The first undoes the last heal of one operation. The second puts Crossbar's spec back.

The queryIds and features in the spec were the last ones known to work. They were written by hand and haven't all been run against live x.com yet, so expect the first calls of some ops to heal themselves. If one keeps failing, re-learn it from your signed-in browser with api-anything's learner, e.g. for posting:

npx api-anything add x createPost --write --trigger https://x.com/compose/post --example text="test one" --example2 text="test two" --steps '[{"action":"fill","selector":"[data-testid=\"tweetTextarea_0\"]","value":"{text}"},{"action":"click","selector":"[data-testid=\"tweetButton\"]"}]'

--write stops the request in the browser, so learning never posts anything.

🗺️ Roadmap

• Images and video in posts (X's chunked media upload)

• Polls, scheduled posts

• Editing and pinning posts, lists, communities, profile editing

• Starting a DM with someone who has no conversation with you yet

• Spaces

PRs welcome. Most of these are one new operation in scripts/build-spec.mjs and one tool in src/mcp.mjs.

🤝 Be a good citizen

This is your own account, driven at human pace. api-anything waits about 1 s between calls to a site and backs off on rate limits. X's terms restrict automation: don't use Crossbar for spam, bulk following, or anything you wouldn't do by hand. Your account is your responsibility.

🛠️ Develop

npm test

npm test runs 50 offline tests against api-anything (no network). After editing the spec generator, run npm run build:spec. Check the plugin with claude plugin validate ..

⭐ Star history

If Crossbar saved you an X API bill, a star helps others find it.

MIT licensed · Made by Prantik Medhi · Built on api-anything