jurre/onebox

Onebox is a Ruby library that converts plain URLs into rich, visual previews. When someone pastes a link to a YouTube video, an Amazon product, or an image, it automatically generates an embedded preview, like a video player or a product card with a title, image, and description, instead of just showing the raw link text. You pass it a URL, and it returns an HTML snippet ready to display in your app. It handles the work of fetching the page, extracting relevant metadata like titles and thumbnails, and formatting everything into a nice-looking preview. It also includes its own caching system so it doesn't repeatedly fetch the same URL, and you can swap in your own cache if you prefer. This is useful for anyone building an app with user-generated content, forums, comment systems, chat applications, or social feeds. For instance, if you run a discussion platform and someone shares a link to a movie trailer, you'd want that link to appear as an embedded video player rather than a boring blue URL. That's exactly what this does. It was originally built for Discourse, a popular forum platform, then extracted into a standalone tool anyone can use. It supports many popular sites out of the box and is designed to be extensible. If a site supports standard embed protocols like oEmbed or Open Graph, adding support can be as simple as whitelisting the URL. For sites that don't follow those standards, developers can write a custom engine that parses the page and extracts the needed data. The project also includes a development server so you can test how different URLs will look before deploying.