Pick one bracket format for your URLs and stick with it. Search Engine Journal reported Oct. 21 that Google Search Advocate John Mueller said on Bluesky on Monday, Oct. 19, that raw square brackets and their percent-encoded versions, %5B and %5D, are separate URLs.
Mueller said he would have guessed they were equivalent. He answered a question from Vanessa Fox, citing RFC 3986, the standard for URI syntax, which treats such swaps as non-equivalent. If a server returns identical content for both, Google will crawl each and may pick one version.
Mueller advised keeping links, canonical tags, sitemaps, and structured data consistent. He said existing sites using raw brackets should not expect problems, but he would not build a new site that way, and other crawlers may be less forgiving.
Teams with filter parameters like ?filter[]= should audit canonicals and internal links for mixed forms. Mismatches hand Google the choice you could have made.
Reported by Matt G. Southern at Search Engine Journal on Oct. 21, 2026, based on John Mueller’s Bluesky post of Oct. 19.
