Compare two ready snapshots the account may read, captured at the same width and check mode, at no charge: no site is opened, so nothing is drawn from the free allowance, a balance or an allowance, and a dry run quotes 0.00. Needs an account-bound key. The compare is recorded under that account: saved while it is Pro (at most 50 saved), otherwise removed with its files 30 days after creation. The cap, a missing or unready snapshot and an incomparable pair are refused before the job starts. Answers the POST /jobs shape plus compareId, which equals jobId.

Site A, a snapshot the account owns or may read.

Site B, captured at the same width and check mode.

Visual diff tolerance as a fraction from 0 (exact) to 1: 0.05 means 5%. The web app takes a percentage; the API does not.

Optional spend cap in USD. A job priced above it is refused before any challenge, so an auto-paying client is never asked for more.

Quote only: runs every check and the pricing, then answers the page count and exact amount. Nothing is charged, the free allowance is not used and no job starts; the same body without dryRun is priced from the retained result.

Optional https URL (port 443) that receives one JSON POST when the job ends (jobId, status, summary, links; never the jobToken), a nudge to read the job. Public hosts only, no redirects followed, retried twice; delivery never affects the job.

The page count the job would be charged for.

The exact amount the same body without dryRun is charged.

For a request with no credential and no prepaid key: the comparison pages the client address may still run free today, read without consuming any.

For a request with no credential and no prepaid key: true when the same body sent now without dryRun would run free (the priced pages are within allowanceRemaining and the shared daily pool).