3v3.dev Connect page

Connect docs · Claude

Connect 3V3 to Claude (claude.ai and Claude Desktop)

One address, https://mcp.3v3.dev, then sign in to 3V3 and press Allow. No key to copy.

Claude's page: Free (one custom connector), Pro, Max, Team and Enterprise.

Steps

  1. In claude.ai or Claude Desktop, open Customize → Connectors, click + Add, then Add custom connector.
  2. Name it 3V3 and paste the address https://mcp.3v3.dev. Click Continue: Claude reads how 3V3 signs people in by itself.
  3. Choose as below, then click Add.
    Claude's dialog: what to choose
    Authentication
    Sign in now
    OAuth client
    Use Claude's published identity (Recommended) — or Register automatically; 3V3 takes both
    Request headers
    none
  4. A 3V3 window opens: sign in, then press Allow.
    3V3's page: Claude wants to design boards in your 3V3 account, with Deny and Allow
    3V3's own page, in a window your app opens: it names the app and where it goes back to.
  5. Back in Claude, 3V3 shows as connected and its tools are listed.

On a Team or Enterprise plan an Owner adds it once under Organization settings → Connectors (Add → Custom → Web, then the same steps); members then click Connect on it under Customize → Connectors.

When it works

Your app lists 3V3's 74 tools — create_project, import_kicad_board, list_projects, list_groups, create_group, rename_group, move_board_to_group, get_routing_log and the rest — and your boards are on app.3v3.dev, where you can watch them change and take over at any time. The Connect page lists the app under Connected apps, where Disconnect stops it at once.

The Connect page's Connected apps table, with one app and a Disconnect button
app.3v3.dev/connect: the app you allowed, and Disconnect.

A first ask

Make a 50 × 50 mm board with an ESP32-C3, USB-C power and a status LED. Route it and stop when the check is clean.

With a key instead

For a setup that can't sign in. Make a key on app.3v3.dev/connect (shown once).

In step 3 choose No sign in, and under Request headers add Authorization with the value Bearer 3v3_dev_….

If it stops

What 3V3 says, word for word, and what to do.

When3V3 saysDo this
Your app says it needs to sign in, or 401This endpoint needs your API key: send it as “Authorization: Bearer 3v3_dev_…”. Make one on the Connect an agent page (/connect).An app that signs in does this for you: let it open 3V3's page. A script sends a key.
You disconnected the appThat app was disconnected from your 3V3 account. Connect it again to carry on.Connect it again (the same steps); Disconnect on the Connect page did exactly this.
The sign-in ran outThat sign-in has expired; your app gets a new one on its own.Normally the app refreshes it by itself. If it keeps saying so, sign in again from the app.
A revoked keyThat key was revoked. Make a new one at POST /api/keys.Make a new key on app.3v3.dev/connect and put it where the old one was.
Too fastSlow down: this key has sent 120 messages in the last minute, and the limit is 120 a minute. Wait a minute and carry on.Each key or app may send 120 messages a minute; wait a minute.
Too many boards todayThis key has made 50 boards in the last 24 hours, and the limit is 50 a day. Carry on with one of them, or wait.Each key or app may make 50 boards a day through MCP; your plan has its own monthly count too.
A wrong addressThis address is 3V3's MCP endpoint: https://mcp.3v3.devUse the address exactly, with nothing after it. Opened in a browser it answers 405: it only speaks MCP.

Tried with 3V3. The founder connected claude.ai this way on 7 October 2026 with “Register automatically”; the box logged the sign-in and the first board. “Use Claude's published identity” went live on 3V3 the same night and is tested on our side, not yet from claude.ai by us.

Checked 8 October 2026.