Expressions

An expression decides which requests a rule matches. The UI's rule builder and the text form are two views of the same stored tree; admin converts between them.

Syntax

starts_with(http.request.uri.path, "/api/") and http.request.method in {"POST" "PUT"}
ip.src in {"10.0.0.0/8" 2001:db8::/32}
ssl and (http.host eq "a.example.com" or http.host eq "b.example.com")
http.request.headers["x-tenant"] eq "acme"
not http.request.jwt.claims["role"] in {"admin" "staff"}
true

Element	Form
Combine	and binds tighter than or; not; parentheses
Compare	field operator value
Functions	starts_with(field, "v"), ends_with(field, "v")
Keyed fields	field["key"], key quoted
Strings	"...", escapes \" and \\ only. Bare words work for simple values
Lists	{a "b c" d}, space-separated
Booleans	ssl alone means true; not ssl means false
Match all	true

Fields

Field	Type	Notes
http.request.uri.path, http.request.uri.query	string	The path is normalized; ambiguous encodings such as %5C, and .. segments, are rejected with 400 before any rule runs. %2F stays encoded inside its segment, so match group%2Fproject; %2F hiding a . or .. part (..%2Fadmin) is rejected. A path always starts with /, so eq "search" is rejected: use eq "/search". The query is not decoded: match query values on http.request.uri.args
http.request.full_uri, http.request.uri	string	Not normalized: the path usually keeps the client's percent-encoding, so /%61dmin does not match "/admin". full_uri is https:// when ssl is true, otherwise http://, then http.host (an IPv6 address in square brackets), then http.request.uri. A rule using them gets a warning; match on http.request.uri.path or http.request.uri.args
http.request.uri.args["name"]	list	Query arguments. Names and values are percent-decoded once, and + is a space. The name matches exactly, case included: args["debug"] does not match ?DEBUG=1, which an upstream that ignores name case still reads. Pairs containing ; or a malformed % escape are skipped, and are also dropped from the forwarded query
http.host	string	Lowercase
http.request.method	string	Uppercase
http.request.headers["name"]	list	Header name lowercase
http.request.cookies["name"]	list
http.cookie, http.referer, http.user_agent, http.x_forwarded_for	string
ip.src	ip	The trusted client IP
ip.src.country, ip.src.continent	string	Uppercase. Needs a trusted viewer header
ip.src.asnum	int	Needs a trusted viewer header
ssl, client_cert.verified	bool	Need a trusted viewer header
http.request.version	string	1.0, 1.1, 2.0 or 3.0 for every source, whatever form the CDN sends (HTTP/2 becomes 2.0); any other value is absent. A literal the edge maps the same way, such as HTTP/2, matches as that version with any operator; any other literal, or a pattern such as HTTP/1 that names HTTP, gets a validation warning. Needs a trusted viewer header
tls.client.ja4	string	The client's JA4 TLS fingerprint, such as t13d1516h2_8daaf6152771_02713d6af862. A header value of another shape is absent, and eq or in with a value of another shape is refused. Matched exactly, letter case included. Needs a trusted viewer header. With an ssl source, absent on a request that wasn't HTTPS, since TLS fingerprints exist only for TLS
tls.client.ja3	string	The client's JA3 TLS fingerprint, 32 lowercase hex characters, with the same rules as JA4, including absent on a request that wasn't HTTPS. Needs a trusted viewer header
client.signals	list	Names of the client signals the request shows. Only eq, ne, in and not_in apply, with signal names as values
client.verified_bot	bool	True when ip.src is in a crawler range admin fetched from VERIFIED_BOT_SOURCES. Needs VERIFIED_BOT_SOURCES on admin, or validation refuses the rule; false until admin's first fetch succeeds
http.request.jwt.claims["name"]	list	Verified claims only. Not in the config phase
edge.locale	string	The detected locale. Not in the config phase; values must be in the supported list

A field marked "needs a trusted viewer header" is refused by validation unless the deployment's CDN preset or VIEWER_HEADERS provides it.

Client signals

client.signals lists what a request shows of automation, computed by the edge from the request's headers and viewer fields. A signal is a hint, not proof: match it in a rule set to log only first, and combine it with other conditions. Bot detection has recipes.

Signal	When	Needs
ua_missing	No User-Agent, or an empty one. Then no other signal is set
ua_tool	The User-Agent names an HTTP library, a command-line tool or a scanner, such as curl/, python-requests/, sqlmap or nuclei. Scanners come from the OWASP Core Rule Set's scanner list. Only the first 512 bytes are read
ua_headless	The User-Agent says HeadlessChrome or PhantomJS
browser_no_accept_language	A modern browser without Accept-Language
browser_no_sec_fetch	A modern browser over HTTPS without Sec-Fetch-Mode	ssl
chromium_no_client_hints	Chrome 89 or later over HTTPS without Sec-CH-UA	ssl
client_hints_mismatch	A Chromium browser over HTTPS whose Sec-CH-UA "Chromium" or "Google Chrome" version differs from its User-Agent	ssl
browser_http1	A modern browser over HTTPS with HTTP/1.0 or HTTP/1.1, since browsers negotiate HTTP/2 only over TLS. Never on a WebSocket handshake (Upgrade: websocket, Connection: upgrade and Sec-WebSocket-Key). The handshake headers come from the client, so a client that adds them skips these checks; the exemption exists because browsers open WebSockets over HTTP/1.1.	ssl, http.request.version
browser_tls_mismatch	A modern browser whose JA4 is not TLS 1.3, or negotiated neither h2 nor h3. On a WebSocket handshake only the TLS version is checked. The handshake headers come from the client, so a client that adds them skips these checks; the exemption exists because browsers open WebSockets over HTTP/1.1.	tls.client.ja4

A modern browser is one whose User-Agent claims a version that sends Sec-Fetch-Mode, from MDN's compatibility data: Chrome 76 (and Edge, Opera and other Chromium browsers, which report a Chrome/ version), Firefox 90 and Safari 16.4. Chrome, Firefox and Edge on iOS are never counted, since they send what Safari sends. Browsers send Sec-Fetch-* and client hints only over HTTPS, so those signals need an ssl source. A signal whose source field isn't configured can never fire, and validation refuses a rule that names it.

Operators

Operator	Types	Text form
eq, ne	string, ip, int	eq, ne
contains, starts_with, ends_with	string	contains, functions
wildcard, strict_wildcard	string	wildcard "*.example.com" (ASCII case-insensitive), strict wildcard (case-sensitive)
in, not_in	string, ip (CIDRs allowed), int	in {...}, not ... in {...}
gt, ge, lt, le	int
matches	string	RE2 regex. Only when the deployment sets ALLOW_REGEX=true
is_true, is_false	bool	bare field, not field

not_contains, not_starts_with, not_ends_with and not_in are written with a leading not, for example not http.host contains "x".

On a list field (headers, cookies, query args, claims), a condition matches if any value matches. A negated condition means no value matches.

In wildcards, * matches any characters and the pattern must match the whole value. \* and \\ are the only escapes, and ** is rejected as a likely typo. wildcard folds case for ASCII letters only; other letters must match exactly.

Limits

Limit	Value
Text length	4000 bytes
Conditions	32
Nesting depth	8
A literal value	4096 bytes
A regex	1024 bytes