You want a computer use agent that can drive a desktop or browser task reliably. The Coasty Computer Use API lets you pick between v3 and v4. v3 gives you a tight capture‑predict‑act loop. v4 adds autonomous behavior and a built‑in verifier. Pick the model that fits your budget, latency needs, and how much control you want over the flow.
What the API requires
Both versions start with a POST to /v1/runs. You provide a machine_id, a task, and the cua_version field. The server starts an agent, streams events, and bills $0.05 per agent step. v4 requires no extra parameters but enables autonomous actions and a pass/fail verifier. v3 keeps you in control at each step. The response includes run_id, status, and events you can stream with GET /v1/runs/{id}/events.
curl -X POST https://coasty.ai/v1/runs \
-H "Authorization: Bearer $COASTY_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"machine_id": "vm-abc123",
"task": "Open Chrome and navigate to https://example.com",
"cua_version": "v4",
"max_steps": 100,
"deadline_seconds": 300,
"on_awaiting_human": "pause"
}'v3: predictable loop
- You call POST /v1/runs with cua_version: "v3" and control each agent step.
- The agent streams events that you can inspect to decide the next capture or action.
- Pricing stays at $0.05 per agent step, same as v4.
- Great for workflows where you want to inject custom logic between steps.
v4: autonomous with verifier
- Set cua_version: "v4" to let the server drive the agent autonomously.
- The server includes a built‑in pass/fail verifier to determine success.
- You can still set max_steps, deadline_seconds, and on_awaiting_human.
- Use this when you want a set‑it‑and‑forget‑it agent that handles the flow.
Set cua_version to "v3" when you need control, or "v4" when you want autonomous completion.
Where this beats brittle automation
Most desktop tools rely on brittle selectors and hard‑coded paths. The Coasty Computer Use API lets the agent see the screen, understand context, and act like a human. You can automate complex workflows that change layout, use dynamic elements, or require multi‑step reasoning. You pay only for the steps the agent actually takes, and you can stop or resume runs at any time from the API.
Pick v3 for tight control, v4 for hands‑off autonomy. Build reliable desktop agents with the Coasty Computer Use API. Get your API key at https://coasty.ai/developers.
Want to see this in action?
View Case Studies