Reliable
Every step is checked before the next
Independent Judges read the screen and confirm a step worked before Sai moves on. That is how Sai reached 79.38% on OSWorld 2.1, the highest partial score on the official leaderboard.
Compare
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Sai API vs Browserbase
Browserbase is cloud headless-browser infrastructure, with the open-source Stagehand SDK (MIT) for writing browser agents and automations. The Sai API is a computer-use agent on a full computer, so a task can cross websites and desktop apps. Send a task in plain English and get the result back.
- Highest partial score on OSWorld 2.1
- 79.38%
- per task, the only cost published on the leaderboard
- $14.34
- to add Sai to Claude Code, Codex or Cursor
- 1 command
Sai API vs Browserbase, side by side
As of October 2026
| Capability | Sai API | Browserbase |
|---|---|---|
| What you get | ||
| Product | A working computer-use agent (Sai) behind one API | Cloud headless-browser infrastructure plus open-source Stagehand SDK (MIT) |
| Computer included | Hosted Windows or Linux cloud computer, or your own Mac or Windows with the Sai desktop app | Yes, a hosted cloud browser in a dedicated VM per session |
| Operating systems | Windows or Linux in the cloud; macOS and Windows on your own machine | Browser only (Chromium-based) |
| Native desktop apps | Yes: desktop apps on Windows, Linux and macOS, not just a browser | No |
| Agent loop and action execution | Built in: send a task in plain English, get the result | Yes: Stagehand agent() with DOM, CUA and Hybrid modes (15 steps by default) |
| Setup / time to first task | Create an API key, add one MCP command (about a minute) | Minutes: API key plus npm/pip install (vendor claim) |
| Reliability and cost | ||
| Benchmark | Highest partial score on the official OSWorld 2.1 leaderboard: 79.38% (Sai w/ Claude Opus 5, 500 steps, Oct 2026). Binary success 41.67%, #2 behind Claude Opus 5 (44.33%). Trajectories public on Hugging Face | No published Stagehand task-success score; Stagehand v4 claims 2x faster, ~80% fewer tokens than Playwright |
| Step verification | Independent Judges check the screen before each next step | Not documented |
| Pricing | Credits per request. Free plan: one shared Windows cloud computer with daily limits. Paid: dedicated computers and top-ups. | Free $0; Developer $20/mo (100 browser-hrs); Startup $99/mo (500 hrs); Scale custom |
| Cost per task / cost drivers | $14.34 per OSWorld 2.1 task, the only leaderboard entry with a published cost (OSWorld 2.0: $15.70) | Browser-hours, proxy GB ($10–12/GB), LLM tokens, search/fetch calls; 1-minute minimum per session |
| Repeat runs | Learns a workflow once, then replays it as self-healing code: up to 90% fewer tokens on repetitive tasks | Server-side cache for act/observe/extract; cache hits use no LLM tokens |
| Control and safety | ||
| Human approval | Built in: approve, approve for this task, or deny; link-only approvals for sign-ins and credentials | Interactive live view lets a human take control; no approval gates in agent() |
| Live view / takeover | Live view to watch tasks and answer approvals. No manual takeover | Embeddable live view (read-only or interactive); every session recorded by default |
| Data and compliance | SOC 2 Type II and HIPAA. Runs on Simular's cloud computer or your own machine. | SOC 2 Type II; HIPAA with BAA (Scale); 4 regions (US, EU, APAC) |
| Operations | ||
| Sessions and persistence | Context carries across tasks on a computer; reset with new-session. | Max 6 h per session (15 min on Free); Contexts persist cookies and storage |
| Concurrency and limits | One task per computer at a time; 60 messages per hour; paid plans add dedicated computers | Concurrency: Free 3 / Developer 25 / Startup 100 / Scale 250+ |
| Fit in your stack | ||
| Coding agents / MCP | Official MCP server (@simular-ai/sai-mcp) for Claude Code, Codex, Cursor and any stdio MCP client | Hosted MCP (6 tools) for Claude Code, Cursor, Claude Desktop; repo archived |
| Model choice | Model-agnostic: Anthropic, OpenAI, Google, MiniMax, xAI, OpenRouter, or auto | OpenAI, Anthropic, Google, Groq, Cerebras built in; any model via callback |
| SDKs / languages | HTTP API (curl, Python, Node examples) plus the MCP server on npm | Stagehand in TypeScript, Python, Go; Browserbase Node and Python SDKs |
| Free tier | Yes: free plan includes a shared Windows cloud computer (daily limits) | Yes: 1 browser-hour, 3 concurrent browsers, 15 min sessions, $5 tokens |
What unifies the Sai API
Four things every task gets, without extra code.
Efficient
Learn once, repeat for less
The first run works the task out. After that, Sai replays it as self-healing code instead of reasoning through every screen, using up to 90% fewer tokens on repetitive tasks.
Ready
A whole computer, already running
Sai works on a hosted Windows or Linux cloud computer, or on your own Mac or Windows machine. It opens apps, clicks and types in desktop software that has no API. No VMs or display drivers to manage.
Composable
Plugs into the agents you already use
Add Sai to Claude Code, Codex or Cursor with one MCP command, or call one HTTP endpoint from any language. It pauses for your approval before sign-ins and other sensitive steps.
Frequently asked questions
What is the difference between the Sai API and Browserbase?
Browserbase hosts cloud browsers, each in a dedicated VM per session, and Stagehand’s agent() drives them in DOM, CUA or hybrid mode, 15 steps by default. The Sai API runs Sai on a whole computer, a hosted Windows or Linux cloud computer or your own Mac or Windows machine, so a task can use websites and native desktop apps.
Can Browserbase operate desktop apps?
No. Browserbase sessions are Chromium-based browsers only. Sai operates desktop apps on Windows, Linux and macOS as well as websites.
How is Browserbase priced compared with the Sai API?
Browserbase plans are Free, Developer ($20/mo, 100 browser-hours), Startup ($99/mo, 500 hours) and custom Scale. Costs add up from browser-hours, proxy traffic ($10–12 per GB), LLM tokens and search or fetch calls, with a one-minute minimum per session. The Sai API is billed in credits per request, and on OSWorld 2.1 Sai completed tasks at $14.34 each.
How long can a session run?
Browserbase sessions run up to 6 hours (15 minutes on the free plan), and Contexts keep cookies and storage between sessions. On Sai, context carries across tasks on the same computer until you start a new session.
Does Browserbase have an MCP server?
Browserbase’s docs list a hosted MCP server with six tools for Claude Code, Cursor and Claude Desktop, though its GitHub repository was archived on July 20, 2026. Sai has an official MCP server, @simular-ai/sai-mcp, for Claude Code, Codex, Cursor and any stdio MCP client.
How do approvals and live view work?
Browserbase has an embeddable live view, read-only or interactive, and records every session by default; a person can take control, but agent() has no approval gates. Sai asks before consequential steps with approve, approve for this task or deny, and sign-ins and credentials are approved through a link.
When is Browserbase the better choice?
For large-scale parallel web work: cheaper DOM-level actions, anti-bot features, Contexts, cached replays that use no LLM tokens, SOC 2 and HIPAA, and a mature open-source SDK. Choose the Sai API when the task needs a full computer with desktop apps, step checks and built-in approvals.
How do I get started with the Sai API?
Sign in at platform.simular.ai and create an API key. Add Sai to Claude Code, Codex or Cursor with one MCP command, or call the HTTP API from any language. The free plan includes a shared Windows cloud computer with daily limits.
Skip the harness. Ship the agent.
Get an API key in a minute, or talk to us about running Sai at scale.