Definition
IndexNow is an open protocol (indexnow.org) that lets websites instantly notify participating search engines — including Bing and Yandex — when URLs are added, updated or deleted, instead of waiting for recrawls. A site hosts a key file and POSTs changed URLs to the API. Implementation is deliberately light: generate a key, host the key file at your site root, and POST changed URLs to api.indexnow.org — one request can carry up to 10,000 URLs. Google does not participate; it relies on sitemaps and its own crawl scheduling. For GEO, IndexNow matters because Bing's index feeds Microsoft Copilot and is one of the retrieval sources in the ChatGPT search stack — fast Bing indexing shortens the path from publish to AI-citable. The protocol only signals that a URL changed; participating engines still decide whether and when to crawl and index it, so IndexNow shortens discovery, not evaluation.