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Nginx · The edge of your stack

How does Nginx choose between competing locations?

Mediumlocation matchingprecedenceroutingUpdated Oct 2026
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Short answer

Nginx checks the exact match first, remembers the longest prefix, then evaluates regexes in order unless the winning prefix used ^~. If no regex matches, the remembered prefix is used.

The matching algorithm is the source of many routing bugs. It is not simply the longest string or the first block in the file. Exact matches win immediately, a ^~ prefix suppresses regex checking, and otherwise regexes are tried in config order.

nginx
location = /static/app.js {
    return 200 "exact";
}

location ^~ /static/ {
    return 200 "prefix";
}

location ~* \.js$ {
    return 200 "regex";
}

location / {
    return 200 "fallback";
}
A request for /static/app.js hits the exact location. A request for /static/logo.svg hits the ^~ prefix, not the regex, because ^~ wins and stops regex evaluation.

The evaluation order

  • Find and use an exact = match immediately
  • Record the longest matching prefix location
  • If that prefix has ^~, use it and skip regexes
  • Otherwise test regex locations in the order they appear and use the first match
  • If no regex matches, use the remembered prefix location
Config order matters for regexes but not for prefix length. Two overlapping regexes can produce surprising results, so keep them specific and test with nginx -T and real request paths.

Follow-ups you should expect

Interviewers use these to check whether the first answer was understanding or memorisation.

  1. 1Why did a regex location not run for a path under a ^~ location?
  2. 2What wins between a longer prefix and a matching regex?
  3. 3Do nested locations change the matching order?
  4. 4How would you debug which location handled a request?

Say it in the interview

Nginx first checks for an exact match. Then it finds the longest prefix and, if that prefix is marked with ^~, it stops there. Otherwise it evaluates regexes in file order and falls back to the remembered prefix if none match. Most surprises come from ^~ or from assuming a longer prefix beats a regex, so I test the real paths.

Use this as a model, not a script. Saying it in your own words is what makes it survive follow-up pressure.

Related questions

MediumWhat are location blocks and which modifiers exist?MediumHow does try_files work?HardHow do you debug a failing Nginx request in production?

Reading is step one

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