Official gold price widget
The official branded widget includes its required credit inside the iframe: Powered by goldprice.dev. Personal and commercial websites may use it free without an account or API key, provided the iframe is not modified and the credit remains visible. White-label or modified presentation rights require a separate Enterprise agreement.
API data in commercial products
No plan requires a credit, credit link or attribution, including Free, older Pro and Realtime Pro. A link to https://goldprice.dev is welcome but optional. The official widget keeps its built-in credit. Any plan covers any number of websites and apps operated by you or companies that control, are controlled by, or are under common control with you.
Other sources
The sources[] array (add ?include=sources to any /v1/prices request) carries the source identifier, display name, price, fetched_at, and source_timestamp for the feed that produced the price you received. See /methodology for the calculation and validation approach.
Questions on commercial use or attribution placement: email hello@goldprice.dev.