Simular Platform (Sai API)

Sai is Simular's computer-use agent, #1 on OSWorld 2.0 (73%). Give it a task in plain English and it does the work on a real Windows or macOS computer the way a person would, by seeing the screen, clicking and typing, so your agent can get things done where there is no API: web apps behind a login, admin consoles, desktop software, forms with no import. Run a workflow once and Sai can save it as code: later runs replay that code and ask the model only where the screen matters, so they are faster and cheaper, and the agent takes over when the UI changes. Coding agents (Claude Code, Codex, Cursor) use it through the @simular-ai/sai-mcp MCP server. The free plan includes a cloud computer.

When to use Sai instead of writing code

Use Sai when:

Write code yourself when:

Run once, replay as code

Most computer-use agents re-plan every step on every run. Sai can turn a workflow it has done into a reusable skill: the steps that stay the same become code, and the model is asked only about what depends on the screen.

  1. Run the task once with Sai.
  2. In the same conversation, ask: Save this as a replayable skill named invoice_export, with vendor and month as parameters.
  3. Next time, ask: Run invoice_export for vendor Acme, month March. Sai replays the code, and when a step breaks because the UI changed, the agent takes over from there.

Example tasks

Getting started

  1. 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.
  2. 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.
  3. 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

Debug with curl

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

curl -N https://api.simular.ai/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"}'

Docs

Research

Optional