Automating Form Filling and Checkout Flows Over the Computer Use API
Checkout flows are the hardest part of web automation. Forms change layout, hidden fields appear, and APIs go down. A computer use agent sees the screen like a human, clicks inputs, and types data, which makes checkout bots far more resilient than API-only or selector-based tools. The Coasty Computer Use API lets you drive real desktops and browsers through a simple HTTP API, with predictable pricing and powerful task-run primitives.
How it works
You send a task describing the action to the Coasty server. The server provisions a machine, boots the desktop or browser, and runs a computer use agent. The API returns a task status (queued, running, awaiting_human, succeeded, failed, cancelled, timed_out) and an event stream that you can reconnect with Last-Event-ID. For each step the agent takes, you pay $0.05. You can also use stateful sessions to preserve trajectory memory between calls.
curl -X POST https://coasty.ai/v1/runs \
-H "Authorization: Bearer $COASTY_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"machine_id": "us-east-1-prod",
"task": "Fill the checkout form on https://example.com/checkout with name=John Doe, [email protected], phone=555-0123, address=123 Main St, city=New York, zip=10001, and submit."
}'
Checkout with workflow orchestration
- ●POST /v1/workflows defines a versioned JSON DSL of runs with task, assert, if, loop, parallel, human_approval, retry, succeed, fail steps.
- ●Task steps are billed $0.05 each, so your workflow cost is predictable.
- ●You can hard guard with budget_cents, max_iterations, and deadline_seconds.
- ●On await_human you can set on_awaiting_human to pause, fail, or cancel to enforce SLAs.
For checkout flows, define a workflow with task steps to fill form, assert success, and then succeed or fail.
Where this beats brittle automation
Selector-based bots break when classes or IDs change. API-only tools miss hidden or client-side validation fields. A computer use agent watches the screen, reads text, and clicks inputs naturally. It works across browsers, desktop environments, and any app with a visible UI, so you can automate modern checkout flows without maintaining brittle selectors.
Next steps
Start automating checkout flows with the Coasty Computer Use API. Get a key at https://coasty.ai/developers and read the full docs at https://coasty.ai/docs.