Paste a raw RSS 2.0, Atom 1.0, or JSON Feed 1.1 document and preview it the way a reader would — channel metadata, item titles, links, publish dates, authors, and categories. Auto-detects the format, warns on missing required elements per the spec, and never leaves your browser.
RSS 2.0 (2003) requires a single <channel> with title, link, and description. Items require at least a title or a description. Atom 1.0 (RFC 4287) requires id, title, and updated at both the feed and entry level. Content may live in <content type="html">, <summary>, or as XHTML. JSON Feed 1.1 (2020) requires version, title, and an items array where each item needs an id. This viewer follows those three specs and flags likely mistakes.