What is the difference between ~, ~*, and ^~?

~ is case-sensitive regex match; ~* is case-insensitive regex match; ^~ is preferential prefix match — if it matches, nginx stops looking at regex locations. Plain prefix matches are weakest and overridden by any regex match.

What regex flavor does nginx use?

PCRE (or PCRE2 in recent builds). Most PCRE features are available, though embedded code (?{...}) and a few exotic constructs are disabled at compile time for safety.

Does the tester contact the server?

No. The location directive is parsed and matched against the URL in your browser. No request is made.

nginx location · modifiers · capture groups

Test an nginx location block

Paste any location directive plus a URL. See the modifier, match mode, and capture groups. Runs locally.

Nginx Location Tester

Match

yes

case-sensitive regex

Modifier

type

Captures

groups

Status

ready

live

input · location + URL

location directive

modifier:~pattern:^/api/(.*)$

Request URL

= exact match (highest priority)

^~ prefix match, skip regex if matched

~ case-sensitive regex

~* case-insensitive regex

(no modifier) prefix match

output · match + mode

matches

case-sensitive regex

captures: $1=users/42

Quick Start

How to test an nginx location block

Drop in a location directive and a URL. See whether the modifier matches, how (exact, prefix, regex), and any captured groups.

01
Paste directive
Modifier (=, ^~, ~, ~*) is auto-detected. Trailing brace optional.
Patterns compile through the JavaScript RegExp constructor, so syntax errors surface immediately and engine quirks like Unicode property escapes (\p{L}) work when the u flag is on.
patternECMAScriptliterallive
input · literaldirective · regex
location ~ ^/api/(.*)$
loaded · ECMAScriptPCRE · ready
02
Paste URL
The request path — query strings are stripped before matching.
Each flag character mirrors the ECMAScript literal: g enables iteration, i folds case, m anchors per line, s lets . match newlines, u unlocks proper Unicode, y is sticky, and d emits indices.
flagsoptionsg · i · mlive
config · optionsurl · flags
/api/users/42
flags applied · liveECMA · live
03
Read outcome
Match verdict, mode name (exact/prefix/regex), and capture groups.
Watch for catastrophic backtracking on nested quantifiers — a common ReDoS source. The tool caps match counts to keep the page responsive on pathological patterns.
matchgroupshighlightReDoS-safe
run · outputresult · matches
ok regex match $1=users/42
matches · livegroups · live
04
Copy or export
Grab the output as JSON, CSV, or plain text — ready for your editor or pipeline.
Copy writes via navigator.clipboard.writeText; downloads use a Blob and object URL, so nothing transits the network and the output is byte-identical to what you see on screen.
copyexportclipboardblob
export · exportedready · saved
Copied
ready to shipsuccess

Pro tips

Regex patterns that don't melt down

Use named groups

(?<year>\d{4}) reads better than $1 and survives reordering. Supported in ECMAScript 2018+.

Anchor strictly

Use ^/$ with the m flag when matching whole lines. Without anchors, partial matches sneak through.

Avoid catastrophic backtracking

Nested quantifiers like (a+)+ can explode. Run patterns through ReDoS Detector first.

Escape every literal

Backslash any meta character you want literally: \.\$\^\*\+\?\[\]\{\}\|\\.

Test edge cases

Empty string, single character, unicode, the maximum length you expect — write fixtures for each.

Patterns aren’t parsers

Don’t parse HTML, JSON, or balanced parens with regex. Use a proper parser when the grammar is recursive.

Use Cases

When to test locations

Authoring and auditing nginx routing.

Debug 404s

Confirm the location block that should serve the URL. Compiles through the JavaScript RegExp constructor — engine quirks (Unicode property escapes, sticky matching, named groups) work when their flags are on. Error messages cite the exact position of any syntax issue.

ReDoS-safe

Author configs

Iterate fast on routing rules. Pairs with the ReDoS detector to catch catastrophic backtracking before you deploy. A pattern that handles 1k-character input fine can become a denial-of-service vector on attacker-controlled 1M-character input.

ECMA-compliant

Migration

Verify new locations cover legacy URLs. Output exports as JavaScript, Python re, Java util.regex, .NET System.Text.RegularExpressions, PCRE, and POSIX — language quirks are highlighted on conversion so you don't ship a JS-only pattern to a Go service.

spec-grade

Audit

Sanity-check production config snippets. Capture groups (named or numbered) round-trip cleanly into replacement strings, JSON output, or CSV extraction without re-typing. Backreferences ($1, ${name}) preserve semantics across languages.

cross-engine

Teach modifiers

Show how =, ^~, ~ differ. Test against edge cases — empty input, single character, max length, multibyte boundaries — to catch off-by-one and zero-length match bugs before they reach production.

test-ready

Document routing

Paste outcomes into a runbook. All matching runs client-side so secret patterns never leave the browser. Useful when the pattern itself is sensitive (PII regexes, internal data formats, security filters).

production-ready

FAQ

Frequently asked questions

What's the priority?

1) =, 2) ^~, 3) ~/~*, 4) prefix. This tool tests one block — nginx's resolution across multiple blocks isn't modelled.

Is the query string considered?

No — nginx matches only the path. Query strings are stripped before matching.

Case sensitivity?

~ is case-sensitive, ~* is case-insensitive. Prefix matches are case-sensitive too.

What about named locations?

@named locations aren't modelled — this tool tests standard URL routing.

Is anything sent to a server?

No. The tool runs entirely in your browser — your pattern and sample text never leave the page.

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Something missing?

Tell us what you need. We ship the top requests every two weeks.

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