Open Graph is a standard for HTML meta tags. Apps like Slack and Discord just make a request to the given URL (locally or in their servers) and read those tags.

Open Graph is a standard for HTML meta tags. Apps like Slack and Discord just make a request to the given URL (locally or in their servers) and read those tags. Then they choose how that information should be displayed. No HTML injection occurs. https://ogp.me https://ogp.me