Sai API

Sai is Simular's computer-use agent. Give it a task in plain English and it does the work on a Windows cloud computer — opening apps, clicking, typing — then returns the result. Coding agents (Claude Code, Codex, Cursor) use it through the @simular-ai/sai-mcp MCP server. The free plan includes a cloud computer.

Getting started

Sign in with Google at https://platform.simular.ai/sign-in (a phone number is required) and create an API key at https://platform.simular.ai/api-keys. Keys start with sapi_ and are shown once.
Add Sai to your coding agent as an MCP server, replacing sapi_YOUR_KEY with the key. Node.js 22.12 or newer is required.
Ask the agent for a task, for example: Use Sai to open Notepad on my cloud computer, type "Hello from Sai", and tell me the window title.

Claude Code

claude mcp add sai -e SAI_API_KEY=sapi_YOUR_KEY -- npx -y @simular-ai/sai-mcp

Optional: install the Sai skill, which teaches Claude Code the task loop.

npx -y @simular-ai/sai-mcp init-claude

Codex

codex mcp add sai --env SAI_API_KEY=sapi_YOUR_KEY -- npx -y @simular-ai/sai-mcp

Cursor

Add this to ~/.cursor/mcp.json (or .cursor/mcp.json in a project), then restart Cursor. The same block works for any stdio MCP client.

{
  "mcpServers": {
    "sai": {
      "command": "npx",
      "args": [
        "-y",
        "@simular-ai/sai-mcp"
      ],
      "env": {
        "SAI_API_KEY": "sapi_YOUR_KEY"
      }
    }
  }
}

Notes for coding agents

You cannot create the API key yourself. Ask the user to create one at https://platform.simular.ai/api-keys and give it to you, then put it in SAI_API_KEY as shown above.
After adding the server, the user may need to restart the client or reload its MCP servers before the tools appear.
Tools: sai_machines, sai_models, sai_task_start, sai_task_wait, sai_task_approve, sai_task_abort, sai_upload.
The loop: sai_task_start returns a session_id. Call sai_task_wait with it, passing back the cursor, while status is running. idle means text holds Sai's answer.
On needs_approval, decide with sai_task_approve. When the approval is link-only (sign-ins, credentials, phone checks), give approval_url to the user and keep waiting.
Tasks run on a real computer and may act on the user's accounts. Confirm anything irreversible with the user first.

Debug with curl

The raw request behind every task. It streams events until finish.

curl -N https://simular-cloud-api-149671192594.us-central1.run.app/v1/agents/message \
  -H "Authorization: Bearer $SAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"message": "Open Notepad, type Hello from the Sai API, and save it to the desktop as hello.txt"}'