Coasty Computer Use API Pricing: Every Endpoint, Every Cent

Base URL and Authentication

All requests go to https://coasty.ai/v1. Use an X-API-Key header or Authorization: Bearer <key>. Read the key from COASTY_API_KEY environment variable. Keys live at https://coasty.ai/developers/keys.

Vision API: predict endpoint

• ●Endpoint: POST /v1/predict
• ●Cost: $0.05 per call
• ●Request fields (all required):
• ● screenshot (base64 PNG string)
• ● instruction (what to do)
• ● cua_version (string, e.g., 'v3')
• ●Response fields:
• ● actions (array of structured actions)
• ● status (string, loop until 'done')

Grounding API: map screenshot + description to coordinates

• ●Endpoint: POST /v1/ground
• ●Cost: $0.03 per call
• ●Request fields:
• ● screenshot (base64 PNG string)
• ● element_description (what to locate)
• ●Response fields:
• ● x (integer, screen coordinates)
• ● y (integer, screen coordinates)

Stateful trajectory memory: sessions

• ●Endpoint: POST /v1/sessions
• ●Cost: $0.10 for the initial session creation
• ●Response fields:
• ● id (string, session identifier)
• ●Subsequent: POST /v1/sessions/{id}/predict
• ●Cost: $0.04 per predict call
• ●Request fields:
• ● instruction (what to do)
• ● cua_version (string, e.g., 'v3')
• ●Response fields:
• ● actions (array of structured actions)
• ● status (string, loop until 'done')

Task Runs: server-driven agent

• ●Endpoint: POST /v1/runs
• ●Cost: $0.05 per agent step
• ●Request fields:
• ● machine_id (string, VM identifier)
• ● task (string, what the agent does)
• ● cua_version (string, 'v3' or 'v4' for autonomous with pass/fail verifier)
• ● instructions (string, appended to base prompt)
• ● system_prompt (optional string)
• ● max_steps (integer, max API calls)
• ● deadline_seconds (integer, timeout)
• ● on_awaiting_human ('pause', 'fail', or 'cancel')
• ● webhook_url (optional)
• ●Response fields:
• ● id (string, run identifier)
• ● state (string: queued, running, awaiting_human, succeeded, failed, cancelled, timed_out)
• ●Subsequent: GET /v1/runs/{id} for status
• ●Stream: GET /v1/runs/{id}/events for SSE events, reconnect with Last-Event-ID

Workflows: versioned JSON DSL

• ●Endpoint: POST /v1/workflows, POST /v1/workflows/{id}/runs, POST /v1/workflows/runs
• ●Cost: $0.05 per task step inside a workflow
• ●Step types: task, assert, if, loop, parallel, human_approval, retry, succeed, fail
• ●Variables: {{inputs.x}} and stepId.field
• ●Hard guards: budget_cents, max_iterations, deadline_seconds

Machines: provision cloud VMs

• ●Endpoint: POST /v1/machines
• ●Cost: Provision cost applies per VM (not listed as per-call, see docs)
• ●Response fields:
• ● id (string, machine identifier)
• ● status (string: provisioning, running, stopped, etc.)
• ●Operations: start, stop, snapshot

Parse endpoint: pyautogui to structured actions

• ●Endpoint: POST /v1/parse
• ●Cost: Free
• ●Request fields:
• ● pyautogui_script (string, Python pyautogui code)
• ●Response fields:
• ● actions (array of structured actions)

Billing and safety

• ●Prepaid USD wallet: 1 credit = $0.01
• ●Webhooks: HMAC signed header Coasty-Signature: t=unix,v1=hex
• ●Idempotency-Key header for safe retries
• ●Scopes gate key permissions
• ●MCP server lets you drive Coasty from Cursor, Claude Desktop, and other MCP clients

Errors

• ●401: invalid key
• ●402: INSUFFICIENT_CREDITS
• ●403: INSUFFICIENT_SCOPE
• ●429: rate limit
• ●Always JSON with error.code, error.message, error.request_id

Why computer use beats brittle automation

Traditional automation relies on brittle selectors and API-only tools. Computer use agents see the screen, interpret instructions, and act like a human. They navigate dynamic UIs, handle unexpected layouts, and adapt to changes without code updates. This makes them ideal for tasks that span apps, websites, and terminals.