# How to add Runtime to Claude.ai as a custom connector

In Claude, open Customize > Connectors, choose Add custom connector, enter `https://api.withruntime.com/mcp`, and approve in your browser.

**With Runtime connected, Claude in the browser can create a Linux sandbox,
run code in it and hand back files, with no API key pasted anywhere.** The
connector signs in through your browser and receives a key of its own, listed
by name on your keys page and revocable in one click. New accounts get 50 free
sandbox hours with no card, as of 25 September 2026 ([trial](/docs/trial)).

## Add the connector

On a Pro or Max plan:

1. In Claude, go to **Customize > Connectors**.
2. Choose **+**, then **Add custom connector**.
3. Enter the remote MCP server URL: `https://api.withruntime.com/mcp`.
4. Leave **Advanced settings** empty. Runtime's sign-in supports dynamic
   client registration, so it needs no client ID or secret.
5. Choose **Add**.

Claude then opens a Runtime page in your browser:

1. Sign in to Runtime, or create an account.
2. The page shows which app is asking and where the key goes. Check it names
   Claude, then approve **Connect**.
3. Back in Claude, every Runtime tool appears.

## On a Team or Enterprise plan

Only an owner of the Claude organization adds a custom connector:

1. **Organization settings > Connectors**, then **Add**.
2. Hover over **Custom** and choose **Web**.
3. Enter `https://api.withruntime.com/mcp` and choose **Add**.

Each member then opens **Customize > Connectors**, finds Runtime in the list
and chooses **Connect**. Every member approves on Runtime with their own
sign-in, so each gets a separate key that can be revoked alone. Invite them to
your Runtime account first, so the connection lands in the shared account:
see [how to invite your team](/how-to/invite-your-team).

## Use it in a chat

Turn the connector on from the **+** button at the lower left of the chat
box, under **Connectors**. Then ask in plain words:

> Create a Runtime sandbox, install pandas, load this CSV and plot revenue by
> month. Stop the sandbox when you are done.

Claude calls the tools itself. The ones it uses most:

| Tool                              | What Claude does with it                                    |
| --------------------------------- | ----------------------------------------------------------- |
| `runtime_sandbox_create`          | Starts a sandbox and waits until it is running              |
| `runtime_sandbox_exec`            | Runs a command and reads the exit code and output           |
| `runtime_sandbox_files_write`     | Puts your code or data into the sandbox                     |
| `runtime_sandbox_files_read`      | Reads results back                                          |
| `runtime_sandbox_interpreter_run` | A notebook-style cell; charts come back as images           |
| `runtime_sandbox_previews_create` | An HTTPS address for an app it started on a port            |
| `runtime_sandbox_manage`          | Stops, pauses or wakes the sandbox                          |
| `runtime_account_get`             | Your trial time left and your credit                        |
| `runtime_docs_read`               | Any page of Runtime's docs, when it needs to check a detail |

The server answers Claude's first contact with instructions: the quick start,
how to retry safely and how to report a problem. That is why Claude knows to
check `exitCode` and to stop a sandbox at the end.

## How the connection works

| Fact                    | Detail                                                                       |
| ----------------------- | ---------------------------------------------------------------------------- |
| Endpoint                | `https://api.withruntime.com/mcp`, MCP Streamable HTTP                       |
| Sign-in                 | OAuth 2.1 with PKCE and dynamic client registration                          |
| Where Claude calls from | Anthropic's cloud, not your computer                                         |
| Credential              | A key for a new agent named after the app                                    |
| What it can do          | Manage resources and spend prepaid credit across the account                 |
| Revoke                  | [API keys](https://withruntime.com/account/keys), where it is listed by name |
| Free Claude plan        | One custom connector                                                         |

Because Claude reaches the server from Anthropic's cloud, nothing is
installed on your machine, and the connector works wherever you use the same
Claude account.

## Mistakes and how Runtime handles them

- **Approving a request you did not start.** The approval page names the app;
  approve only when it is the Claude you just used.
- **Worrying about spend.** Set a daily spending limit on the connector's row
  at API keys. Past it, a create or wake fails with `spending_limit_reached`
  and nothing is charged.
- **Leaving sandboxes running.** Ask Claude to stop them, or let them pause:
  a sandbox made with default settings and never used pauses after 300
  seconds and stops paying the running rate.
- **Tools with old names in a saved prompt.** On 24 September 2026 every tool
  took its product's name, such as `runtime_sandbox_exec`. A call to an old
  name fails and names the new one.

## Related

- [How to add Runtime to Cursor](/how-to/add-runtime-to-cursor)
- [Claude Code in a sandbox](/integrations/claude-code) for Claude Code in a
  terminal
- [Code interpreter for chatbots](/use-cases/code-interpreter-for-chatbots)
- [Runtime Cloud MCP](/docs/mcp#remote-connection)

## Sources

Checked 25 September 2026.

- [Getting started with custom connectors using remote MCP](https://support.claude.com/en/articles/11175166-getting-started-with-custom-connectors-using-remote-mcp),
  Claude Help Center

Facts on this page were checked on 25 September 2026.