# 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 return files. No API key is pasted anywhere.** The connector signs in through your browser and receives a key of its own. The key is listed by name on your keys page and can be revoked in one click. Every new account gets 100 free hours of a 1 GB machine in its first 30 days with no card, as of 25 October 2026 ([trial](/docs/included-usage)). ## Add the connector On a Pro or Max plan: 1. In Claude, go to **Customize > Connectors**. 2. Choose **+ Add**, then **Add custom connector**. 3. Enter a name, such as Runtime, and the remote MCP server URL: `https://api.withruntime.com/mcp`. Choose **Continue**, then **Continue** again on the detected authentication settings. 4. Keep the recommended OAuth client, **Use Claude's published identity**. Runtime's sign-in accepts client metadata documents and 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 that 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 (on Enterprise, also a role with Manage access to Libraries): 1. **Organization settings > Connectors**, then **Add**. 2. Hover over **Custom** and choose **Web**. 3. Enter a name and `https://api.withruntime.com/mcp`, choose **Continue** twice, then **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. Each gets a separate key that can be revoked alone. Invite members 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_sandboxes_create` | Starts a sandbox and waits until it is running | | `runtime_sandboxes_exec` | Runs a command and reads the exit code and output | | `runtime_sandboxes_files_write` | Puts your code or data into the sandbox | | `runtime_sandboxes_files_read` | Reads results back | | `runtime_sandboxes_interpreter_run` | A notebook-style cell; charts come back as images | | `runtime_sandboxes_previews` | An HTTPS address for an app it started on a port | | `runtime_sandboxes_manage` | Stops, pauses or wakes the sandbox | | `runtime_account` | Your free usage 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. 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 the limit, 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 pauses itself after 300 seconds with nothing happening in it, and then 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_sandboxes_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 October 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 October 2026.