GTM Regex Cheatsheet

GTM uses ECMAScript-flavoured regex throughout: in trigger conditions, variable transformations, lookup tables, and regex table variables. This cheatsheet covers the patterns you will reach for constantly. All patterns are tested against the GTM engine.

Tip

GTM regex matching is case-sensitive by default. Select “Ignore Case” in trigger conditions or use the (?i) flag equivalent for case-insensitive matching. In GTM, use the “matches RegEx (ignore case)” operator rather than the (?i) flag — GTM does not support inline flags.

URL and path matching

Pattern	Matches	Notes
^/blog/	Paths starting with /blog/	Use ^ to anchor to path start
^/blog$	Exactly /blog with no trailing slash	$ anchors to end
^/blog/?$	/blog and /blog/	? makes the trailing slash optional
^/(shop|store)/	/shop/ and /store/	Alternation with | (escaped in some contexts)
/product/[0-9]+	/product/123, /product/9876	[0-9]+ = one or more digits
/product/[a-z0-9\-]+	/product/blue-running-shoes	Slug pattern
\?	A literal ? in the URL	Escape special chars with \
[?&]utm_source=	?utm_source= or &utm_source=	Matches UTM parameter anywhere in query string
^/thank.you	/thank-you, /thank_you, /thankyou	. matches any character — may match too broadly
^/thank\-you	Exactly /thank-you	Escape - with \ to be explicit
checkout	Any URL containing “checkout”	No anchors = contains match
^https://www\.example\.com	Full URL starting with your domain	Escape . in domain names

Hostname patterns

Pattern	Matches	Notes
^www\.example\.com$	Exactly www.example.com	Use with {{Page Hostname}} variable
example\.com$	www.example.com, shop.example.com	Matches any subdomain of example.com
^(www|shop)\.example\.com$	Only www and shop subdomains	Explicit subdomain list
staging|localhost|127\.0\.0\.1	Development environments	Use as a blocking trigger
^(?!www\.)	Any hostname NOT starting with www	Negative lookahead — useful for staging blocks
\.co\.uk$	UK domain variants	Country-code TLD matching

File extension matching

Pattern	Matches	Notes
`.(pdf)(?	$)`	URLs ending in .pdf
`.(pdf|docx?|xlsx?|pptx?)(?	$)`	Common office document types
`.(zip|tar.gz|rar)(?	$)`	Archive files
`.(jpg|jpeg|png|gif|webp|svg)(?	$)`	Image files
`.(mp4|webm|mov|avi)(?	$)`	Video files
`.(mp3|wav|ogg|aac)(?	$)`	Audio files
`.(csv|json|xml)(?	$)`	Data files

Query parameter matching

Pattern	Matches	Notes
[?&]q=([^&]+)	The value of ?q= parameter	Use capture group in a replacement variable
[?&]utm_source=([^&]+)	UTM source value	Combine with regex capture for extraction
[?&]gclid=	Any URL with a Google Click ID	Detect paid traffic
[?&]fbclid=	Any URL with a Facebook Click ID	Detect Facebook paid traffic
[?&](utm_source|utm_medium|utm_campaign)=	Any UTM parameter	Check if URL has any UTM tags

Click text and element matching

Pattern	Matches	Notes
^(Add to Cart|Buy Now)$	Exact button text variants	Case-sensitive; add “(ignore case)” operator
(free trial|sign up|get started)	CTA phrases anywhere in text
^\s*(.*?)\s*$	Text trimmed of leading/trailing whitespace	Use in a Custom JavaScript Variable instead
\d+	Any text containing a number
^\d+$	Text that is only digits

PII detection patterns

Use these in Custom HTML tags to scrub event data before it reaches GA4.

Pattern	Detects	Notes
[a-zA-Z0-9._%+\-]+@[a-zA-Z0-9.\-]+\.[a-zA-Z]{2,}	Email addresses	Standard email regex
\b\d{3}[\s.\-]?\d{3}[\s.\-]?\d{4}\b	US phone numbers (various formats)	Matches 555-123-4567, 555.123.4567, 5551234567
\+?\d{1,3}[\s\-]?\(?\d{1,4}\)?[\s\-]?\d{1,9}([\s\-]\d{1,9})*	International phone numbers	More permissive — adjust for your regions
\b\d{3}\-\d{2}\-\d{4}\b	US Social Security Numbers
\b4[0-9]{12}(?:[0-9]{3})?\b	Visa card numbers
\b5[1-5][0-9]{14}\b	Mastercard numbers
\b3[47][0-9]{13}\b	American Express numbers
\b[0-9]{4}[\s\-]?[0-9]{4}[\s\-]?[0-9]{4}[\s\-]?[0-9]{4}\b	Generic 16-digit card pattern
\b[A-Z]{1,2}[0-9R][0-9A-Z]?\s?[0-9][A-Z]{2}\b	UK postcodes
\b[0-9]{5}(?:\-[0-9]{4})?\b	US ZIP codes (basic, high false-positive rate)	Use sparingly

Caution

PII regex patterns have false-positive risk. A product code like 123-45-6789 could match an SSN pattern. Always review matches before blocking them, and prefer allowlist approaches (only send known-safe fields) over blocklist approaches (try to detect all PII).

Number and value matching

Pattern	Matches	Notes
^\d+$	Integer: 42, 1000	Only digits, entire string
^\d+(\.\d{1,2})?$	Decimal with up to 2 places: 49.99
^\d{1,3}(,\d{3})*(\.\d{2})?$	Formatted number: 1,234.56	European formatting differs
^[+-]?\d+(\.\d+)?$	Any positive or negative number
^\$[\d,]+(\.\d{2})?$	Dollar amount string: $49.99

GTM variable extraction (use with “Replace” in variables)

These regex patterns are used in the Search/Replace field of GTM variables to extract specific parts of a string.

Find	Replace	Use case
.*[?&]q=([^&]*).*	$1	Extract search query from full URL
^https?://[^/]+(.*)	$1	Strip protocol and hostname, return path
^([^?#]*).*	$1	Strip query string and fragment
.*\/([^\/\?]+)(\?.*)?$	$1	Extract last path segment (filename)
\.([a-zA-Z0-9]+)(\?.*)?$	$1	Extract file extension
^.*?\/\/([^\/]+)\/.*$	$1	Extract hostname from full URL

Trigger condition operators

When choosing between GTM’s trigger condition operators:

Use case	Operator	Example
Exact match	equals	Page Path equals /contact
Prefix match	starts with	Page Path starts with /blog
Substring match	contains	Page Path contains checkout
Pattern match	matches RegEx	Page Path matches RegEx ^/(en|fr|de)/
Case-insensitive	matches RegEx (ignore case)	Click Text matches RegEx (ignore case) add to cart
Exclusion	does not match RegEx	Page Hostname does not match RegEx staging|localhost

Common patterns for GTM Lookup Tables

Use these in Regex Table variables to map URL patterns to readable values:

Pattern                          → Output
^/blog/                          → Blog
^/product/                       → Product
^/checkout/                      → Checkout
^/account/                       → Account
^/$                              → Homepage
.*                               → Other  ← Default fallback (put last)

Useful anchors and quantifiers quick reference

Symbol	Meaning	Example
^	Start of string	^/blog
$	End of string	\.html$
.	Any character except newline	p.ge matches page, p1ge
\d	Digit [0-9]	order-\d+
\w	Word char [a-zA-Z0-9_]	\w+
\s	Whitespace	first\sname
\b	Word boundary	\bcat\b won’t match category
*	0 or more	colou*r matches color and colour
+	1 or more	id=\d+
?	0 or 1 (optional)	https?
{n}	Exactly n times	\d{4}
{n,m}	Between n and m times	\d{5,10}
[abc]	Character class	[aeiou]
[^abc]	Negated class	[^?&]+
(a|b)	Alternation	(pdf|docx)
(...)	Capture group	([^&]+)
(?:...)	Non-capturing group	(?:www\.)?

PII Detection & Removal Full recipe for stripping PII from tracking data using these patterns.

Track PDF Downloads File extension regex patterns in action.