---
title: How URL normalization works
description: How URL normalization modifies incoming request URIs before rule evaluation.
image: https://developers.cloudflare.com/core-services-preview.png
---

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# How URL normalization works

URL normalization modifies separators, encoded elements, and literal bytes in incoming URLs so that they conform to a consistent formatting standard.

For example, consider a WAF custom rule that blocks requests whose URLs match `www.example.com/hello`. The rule would not block a request containing an encoded element — `www.example.com/%68ello`. Normalizing incoming URLs on the Cloudflare global network helps simplify rules expressions containing URLs.

The two available types of URL normalization are:

* [RFC 3986 normalization](#rfc-3986-normalization)
* [Cloudflare normalization](#cloudflare-normalization)

The location where URL normalization will occur depends on the [configured settings](https://developers.cloudflare.com/rules/normalization/settings/).

For examples of the different settings and their impact on request URLs, refer to the [URL normalization examples](https://developers.cloudflare.com/rules/normalization/examples/).

## RFC 3986 normalization

The URL normalization performed according to [RFC 3986 ↗](https://www.ietf.org/rfc/rfc3986.txt) is as follows:

* The following unreserved characters are [percent decoded ↗](https://tools.ietf.org/html/rfc3986#section-2.1) (converted from their `%XX` encoded form back to the original character):  
   * Alphabetical characters: `a`\-`z`, `A`\-`Z` (decoded from `%41`\-`%5A` and `%61`\-`%7A`)  
   * Digit characters: `0`\-`9` (decoded from `%30`\-`%39`)  
   * hyphen `-` (`%2D`), period `.` (`%2E`), underscore `_` (`%5F`), and tilde `~` (`%7E`)
* These reserved characters are not encoded or decoded: `: / ? # [ ] @ ! $ & ' ( ) * + , ; =`
* Other characters, for example literal byte values, are percent encoded.
* Percent encoded representations are converted to upper case.
* URL paths are normalized according to the [Remove Dot Segments ↗](https://tools.ietf.org/html/rfc3986#section-5.2.4) protocol.

## Cloudflare normalization

When using the Cloudflare URL normalization, some extra normalization techniques will be applied to URLs of incoming requests, in the following order:

1. Normalize back slashes (`\`) into forward slashes (`/`).
2. Merge successive forward slashes (for example, `//` will be normalized to `/`).
3. Perform [RFC 3986 normalization](#rfc-3986-normalization) of the resulting URL.

```json
{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/rules/","name":"Rules"}},{"@type":"ListItem","position":3,"item":{"@id":"/rules/normalization/","name":"URL normalization"}},{"@type":"ListItem","position":4,"item":{"@id":"/rules/normalization/how-it-works/","name":"How URL normalization works"}}]}
```