Every congress on CongressAgenda is checked against official sources: the congress website, the organizing society, and accrediting bodies. Third-party event directories and aggregators are not accepted as verification sources; the excluded domains are listed in the public source policy.
Each listing carries a confidence level. High means the listing shows the Verified badge: dates, venue, and organizer are confirmed on official sources. Listings also show a last-verified date so you can see how fresh the data is.
The Verified badge cannot be bought. It is the outcome of verification, not a product; listing and verification are free and editorially independent. See also the about page and the open dataset.