URL Parameters

URL parameters, also called query strings, are the parts of a web address that follow a question mark, such as ?colour=blue&sort=price. They pass information to the page, for example to filter products, sort results or track a campaign, and they can create many versions of the same page.

Written by Paul Hoda, SEO consultant since 2005. Last updated 8 November 2026.

How URL parameters work

A parameter is a key and a value joined by an equals sign. Several parameters are joined by ampersands. In /shoes?colour=blue&size=8, the keys are colour and size. Parameters usually do one of two jobs:

  • Active parameters change what is shown: filtering, sorting, pagination, search queries and language choices.
  • Passive parameters do not change the content: tracking codes such as UTM parameters, session IDs and click IDs from ad platforms.

Why parameters cause SEO problems

  • Duplicate content: /shoes, /shoes?sort=price and /shoes?utm_source=email may show the same products. Search engines see separate URLs with near-identical content, creating duplicate content.
  • Wasted crawling: filters can combine into thousands or millions of URLs, using up crawl budget on pages that add nothing.
  • Split signals: links and engagement spread across several versions rather than building up one strong URL.
  • Index bloat: low-value variations can end up indexed, a problem described under index bloat.
  • Messy results: long parameter URLs look less trustworthy in search results and when shared.

How to manage URL parameters

  1. Audit them: crawl the site and check Search Console to see which parameters exist and which are indexed.
  2. Use canonical tags: point parameter versions to the clean URL with a canonical tag where the content is essentially the same.
  3. Link to clean URLs: internal links, sitemaps and canonicals should all use the preferred version.
  4. Give valuable filters their own pages: if people search for something like blue running shoes, consider a static, crawlable category URL with unique content.
  5. Limit crawlable combinations: for faceted navigation, avoid linking to every filter combination, and consider robots.txt rules for parameters that should never be crawled.
  6. Keep order consistent: always output parameters in the same order so ?a=1&b=2 and ?b=2&a=1 do not both exist.
  7. Avoid session IDs in URLs: use cookies instead.

The retired parameter tool

Google Search Console once had a URL Parameters tool for telling Google how to treat each parameter. Google retired it in 2022, saying its systems had become good at working out which parameters matter. Site owners now manage parameters through canonicals, internal linking and robots.txt instead.

Common mistakes

  • Blocking parameter URLs in robots.txt while also relying on canonical tags on them, which Google cannot then see.
  • Adding UTM tags to internal links, which creates duplicates and corrupts analytics data.
  • Letting tracking parameters from email or social campaigns get indexed because pages lack a canonical tag.
  • Noindexing every parameter page, including useful filtered pages people actually search for.

Key Takeaways

  • URL parameters are the query string after a question mark in a URL.
  • They can create duplicate content and waste crawl budget.
  • Canonical tags and clean internal links are the main fixes.
  • Google retired the Search Console URL Parameters tool in 2022.
  • Never put UTM tracking parameters on internal links.

Related Terms

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