What is a redirect?
A redirect is a server response sending a browser or crawler from one URL to another. The status code it uses, 301 or 302, tells the engine whether the move is permanent or temporary, and the two are not interchangeable.
A 301 tells an engine the old URL is gone for good and to transfer its accumulated trust to the new one; a 302 says the move is temporary and the old URL should stay the one that's indexed. Using a 302 for a permanent change is one of the more common technical SEO mistakes, because it works fine for a person clicking the link and silently fails to consolidate ranking signal at the old address.
A redirect implemented in JavaScript rather than as a server response is invisible to any crawler that doesn't execute JavaScript, which includes most AI crawlers. A redirect that works perfectly in a browser can leave those crawlers stuck on the old URL, or on nothing at all, which is worth checking directly rather than assuming a redirect that works in a browser test has worked everywhere.
Related
- Server-side renderingServer-side rendering means the HTML arrives complete from the server. It matters because most AI crawlers do not execute JavaScript, so content injected in the browser is invisible to them.
- IndexationIndexation is whether a search engine has stored your page and is willing to return it. Being crawled is not the same as being indexed, and being indexed is not the same as ranking.
- Canonical tagA canonical tag tells a search engine which URL is the preferred version of a page when several URLs show similar content.
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