@humanwhocodes/crosspost

The Crosspost API is built around two main components:

1. Strategies: Individual implementations for specific services (e.g., TwitterStrategy, MastodonStrategy). Each strategy requires service-specific configuration parameters (like API keys or access tokens).
2. Client: A central Client class that orchestrates posting. You instantiate a Client by passing an array of configured strategy instances to its strategies option. Once configured, the client can broadcast a single message to all registered services or target specific ones.

Supported strategies include:

• BlueskyStrategy
• MastodonStrategy
• TwitterStrategy
• LinkedInStrategy
• DiscordStrategy
• DiscordWebhookStrategy
• TelegramStrategy
• DevtoStrategy
• NostrStrategy (requires Node.js v22+)

import {
	Client,
	TwitterStrategy,
	MastodonStrategy,
	// ... other strategies
} from "@humanwhocodes/crosspost";

const mastodon = new MastodonStrategy({
	accessToken: "your-access-token",
	host: "mastodon.host",
});

const client = new Client({
	strategies: [mastodon],
});

await client.post("Hello world!");

To post to Discord using a bot, follow these steps in the Discord Developer Portal:

1. Create Application: Create a new application and name it.
2. Installation: Under Installation, set Install Link to None and save.
3. Bot Setup:
   • Under Bot, uncheck Public Bot.
   • Under Text Permissions, check Send Messages.
   • Click Reset Token and copy the bot token.
4. Add Bot to Server:
   • Go to OAuth2 > OAuth2 URL Generator.
   • Check bot and under Bot Permissions, check Send Messages.
   • Copy the URL, open it in a browser, and authorize it for your server.
5. Get Channel ID: Enable Developer Mode in Discord (User Settings > Advanced), then right-click the target channel and select Copy Channel ID.

Note: By default, bots can only post to public channels unless granted specific permissions for private channels.

Crosspost can run as a Model Context Protocol (MCP) server, enabling AI agents (like Claude Desktop) to post to social networks.

Start the server:

npx @humanwhocodes/crosspost --mcp -t -m -b

(The flags -t -m -b determine which services are available to the agent).

Claude Desktop Configuration: Add the server to your claude_desktop_config.json file. You can pass environment variables directly in the env block or use CROSSPOST_DOTENV to point to a .env file.

Example Configuration (Direct Env):

{
	"mcpServers": {
		"crosspost": {
			"command": "npx",
			"args": ["@humanwhocodes/crosspost", "-m", "-l", "--mcp"],
			"env": {
				"LINKEDIN_ACCESS_TOKEN": "abcdefghijklmnop",
				"MASTODON_ACCESS_TOKEN": "abcdefghijklmnop",
				"MASTODON_HOST": "mastodon.social"
			}
		}
	}
}

{
	"mcpServers": {
		"crosspost": {
			"command": "npx",
			"args": ["@humanwhocodes/crosspost", "-m", "-l", "--mcp"],
			"env": {
				"CROSSPOST_DOTENV": "/path/to/.env"
			}
		}
	}
}

To post to Slack using a bot, follow these steps in the Slack API website:

1. Create App: Select From scratch, name it, and select your workspace.
2. Permissions: Under OAuth & Permissions > Scopes > Bot Token Scopes, add:
   • chat:write (to send messages)
   • files:write (required for image support)
3. Install: Click Install to Workspace and allow permissions.
4. Token: Copy the Bot User OAuth Token (starts with xoxb-) and set it as the SLACK_TOKEN environment variable.
5. Channel: Right-click the channel in Slack and select Copy link. The channel ID is the part after the last slash (e.g., C1234567890). Set this as SLACK_CHANNEL (or use the channel name like #general).

Note: The bot must be added to the channel (e.g., by mentioning it or using /invite @your-bot-name). The bot can only message users who have previously messaged it or added it to a group.