Connect Claude to SignWith (MCP)

The SignWith MCP server is at https://app.signwith.co/mcp. How you add it depends on where you use Claude. Steps checked against Claude's documentation on 1 October 2026.

Claude Code

Claude Code connects with an API key in a header, or with OAuth sign-in.

With an API key. Create a key in Settings → Developers, put it in an environment variable, then run:

claude mcp add --transport http signwith https://app.signwith.co/mcp \
  --header "Authorization: Bearer $SIGNWITH_API_KEY"

Add --scope user to use SignWith in all your projects, or --scope project to share it with your team through the project's .mcp.json. In a shared .mcp.json, refer to the key by variable so it isn't committed:

{
  "mcpServers": {
    "signwith": {
      "type": "http",
      "url": "https://app.signwith.co/mcp",
      "headers": { "Authorization": "Bearer ${SIGNWITH_API_KEY}" }
    }
  }
}

With OAuth. Add the server without a header, then run /mcp inside Claude Code and follow the steps in your browser to sign in to SignWith:

claude mcp add --transport http signwith https://app.signwith.co/mcp

Check it works. Run claude mcp list, or /mcp inside a session, and look for signwith. Then ask Claude: "Which SignWith templates do I have?"

Claude on the web, desktop and mobile

In the Claude apps, SignWith is a custom connector. Custom connectors are available on Free (one connector), Pro, Max, Team and Enterprise plans. Set it up on the web or desktop; it then works on mobile too.

The button opens Claude's Add custom connector dialog with SignWith filled in; review it and click Add. Or add it by hand.

Free, Pro and Max:

1. In Claude, open Customize → Connectors.
2. Choose Add custom connector.
3. Enter https://app.signwith.co/mcp as the server URL, and click Add.
4. Click Connect. Claude sends you to SignWith: sign in, and choose Full access or View only.

Team and Enterprise: an owner first adds the connector under Organization settings → Connectors (Add, then Custom). Each member then finds it under Customize → Connectors and clicks Connect.

To use it in a chat, turn SignWith on from the + menu, under Connectors.

Some organizations can also add an API key as a request header on a custom connector, a Claude beta feature that isn't available to everyone. If you have it, choose No sign-in, add the authorization header, and type the value as Bearer followed by your key.

What to try

• "List my SignWith templates."
• "Send the NDA template to [email protected], with Grace Hopper as the name."
• "Has everyone signed the lease for 14 Riverside Ave?"
• "Remind the people who haven't signed yet."

Claude asks for your OK before it sends, reminds or cancels anything, unless you've chosen to always allow that tool. Each document uses credits as described in credits and billing.

Troubleshooting

• 401 or "unauthorized" with an API key: check the header is exactly Authorization: Bearer sw_... and that the key isn't revoked or expired. See authentication.
• Claude can read but not send: the connection is View only, or the key is read-only. Reconnect with Full access, or use a full-access key.
• "insufficient_credits": the account is out of credits. Claude can show credit packs and a checkout link, or you can buy credits in SignWith.

All tools and access rules are on the MCP overview.