Are robots directive names and values case-sensitive for Google?

Definition: Google treats the name and content attributes of a robots meta tag as case-insensitive. It also treats the HTTP header name, user-agent name and specified values in X-Robots-Tag as case-insensitive.

Key facts

• Google's robots metadata reference says both the name and content attributes of a robots meta tag are case-insensitive.
• The same reference says that the valid indexing and serving rules are case-insensitive, including the values used in a comma-separated list.
• For X-Robots-Tag, Google says the header, user-agent name and specified values are not case-sensitive.
• Google supports robots for all search engines and googlebot specifically for Google, according to its meta tags documentation.
• The meta tags documentation gives index, follow as the default values, so they do not need to be written explicitly.

What does case-insensitive mean here?

Case-insensitive handling means that changing uppercase and lowercase letters in a supported name or value does not change the directive that Google reads. For example, the following forms use the same tag structure and supported rules:

<meta name="robots" content="noindex,nofollow">
<meta name="RoBoTs" content="NoInDeX,NoFoLlOw">

Google's robots metadata reference states that the name and content attributes are case-insensitive. It separately states that the valid rules are case-insensitive. A directive value still has to be one of the rules Google documents. Case-insensitivity changes letter matching; it does not add an undocumented rule.

The reference also says that multiple rules can be combined in a comma-separated list or placed in separate meta tags. Spaces and letter case therefore belong to different checks: the documented list syntax controls how rules are separated, while case-insensitive matching controls the letters in each supported name or value.

Does the same rule apply to X-Robots-Tag?

Yes. X-Robots-Tag is an HTTP response header that can carry the same rules as a robots meta tag. Google's reference says that rules without a user agent apply to all crawlers, and that the HTTP header, the user-agent name and the specified values are not case-sensitive.

X-Robots-Tag: NoInDeX, NoFoLlOw

The header form matters for resources that are not HTML. Google's meta tags documentation says that the header rule is particularly useful when limiting indexing of non-HTML files such as graphics or other documents. The case rule applies to the header syntax described in Google's documentation, while the resource still has to be available for Google to process its metadata.

Which names does Google recognize?

Google's meta tags documentation describes meta tags as HTML tags that provide additional information to search engines and other clients. It says clients process supported meta tags and ignore tags they do not support. In the robots family, the robots tag applies to all search engines, while googlebot is specific to Google.

The robots metadata reference lists googlebot for text results and googlebot-news for news results as the user-agent tokens Google supports in a robots meta tag. It says other values are ignored. A mixed-case spelling of a supported token remains subject to the case-insensitive rule, while a different token is a separate, unsupported name.

FAQ

Can I write NOINDEX instead of noindex?

Yes. Google documents the rules as case-insensitive, so uppercase letters in a supported directive value are handled like lowercase letters.

Can I write ROBOTS in the meta tag name?

Yes. Google documents the name attribute as case-insensitive. The tag still needs a supported content rule.

Does case-insensitivity apply to every search engine?

The answer is specific to Google. Google's robots metadata reference notes that other search engines may not treat these rules the same way.

Related terms

• Meta robots
• X-Robots-Tag
• How can a robots meta tag target Googlebot separately?
• Which directive wins when robots meta tags conflict?

Sources

1. Google Search Central, "Robots meta tag, data-nosnippet, and X-Robots-Tag specifications", 24 March 2026
2. Google Search Central, "Meta tags and HTML attributes that Google supports", 10 December 2025

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