Starter, Professional and Expert validation reports are each free to generate. There is no subscription, no recurring billing and no card is collected. An account is required so reports can be saved to history, re-downloaded and emailed.
A voluntary "Support Us" contribution link is available in the site header. Contributing is optional and unlocks no additional features, tiers or priority.
Machine-readable fact sheets: /llms.txt and /llms-full.txt.