---
title: Adding rewrite content rules
description: Add rewrite content rules, which modify text in HTTP response bodies as it is served to the client in PingAccess.
component: pingaccess
version: 8.3
page_id: pingaccess:pingaccess_user_interface_reference_guide:pa_adding_rewrite_content_rules
canonical_url: https://docs.pingidentity.com/pingaccess/9.1/pingaccess_user_interface_reference_guide/pa_adding_rewrite_content_rules.html
llms_txt: https://docs.pingidentity.com/pingaccess/llms.txt
docs_for_agents: https://developer.pingidentity.com/build-with-ai/docs-for-agents.md
revdate: January 12, 2024
superseded_by: https://docs.pingidentity.com/pingaccess/9.1/pingaccess_user_interface_reference_guide/pa_adding_rewrite_content_rules.html
section_ids:
before-you-begin: Before you begin
about-this-task: About this task
steps: Steps
rewrite-content-rule-examples: Rewrite content rule examples
---
# Adding rewrite content rules
Add rewrite content rules, which modify text in HTTP response bodies as it is served to the client in PingAccess.
## Before you begin
Confirm that you are not using the [agent](../introduction_to_pingaccess/pa_agent_model.html) model. Rewrite content rules aren't available for agent deployments.
## About this task
A rewrite content rule uses a subset of the Java regular expression syntax that excludes look-behind constructs, such as `\b`, and the boundary matcher, `\G`. If no Java regular expression syntax is used, the rule performs a case-sensitive search and replace.
The most common use case for this rule is to rewrite host names within URLs contained in HTML, JavaScript, or CSS content.
| | |
| - | --------------------------------------------------------------------------------------- |
| | Extensive use of rewrite content rules might have significant performance implications. |
This rule supports content that is either chunked or streamed from the target server. When sent to the client, the content is always chunked.
To add a rewrite content rule:
## Steps
1. Click **Access**, then go to **Rules > Rules**.
2. Click **[icon: plus, set=fa]Add Rule**.
3. In the **Name** field, enter a unique name up to 64 characters long.
Special characters and spaces are allowed.
4. In the **Type** list, select **Rewrite Content**.
5. To define what type of response data to which the rewrite rule applies, enter one or more **Response Content-Types**.
The default values are `text/html`, `text/plain`, and `application/json`. The list is an ordered list.
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| - | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| | Only text-based content types are supported. Text-based content types compressed with gzip, deflate, or compress will decompress prior to rewrite rule processing, however, the content is not re-compressed before sending to the client. |
6. Define one or more sets of **Find and Replace Criteria**.
If multiple criteria are specified, each operation is performed against the original content, effectively applying the rule concurrently.
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| - | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| | Changes can affect CSS, Javascript, and other text-based elements served to the client. Be sure to properly craft the regular expression to avoid unintentionally modifying content. |
7. If the protected application does not return a **Content-Type** header, select **Missing Content-Type Allowed**.
8. If you enable **Missing Content-Type Allowed**, specify the encoding the application returns in the **Missing Content-Type Charset** field.
This field could contain `UTF-8`. A list of valid values is available in the [Oracle Java 8 SE Technical Note](https://docs.oracle.com/javase/8/docs/technotes/guides/intl/encoding.doc.html).
9. If necessary, increase the size of the buffer used to perform the replace operation by clicking **Show Advanced** and entering a value in **Maximum Buffer Size**.
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| - | ------------------------------------------------------------------------------------------------------------------------------------------- |
| | Replacement values cannot be larger than the buffer size. The minimum buffer size you can specify is 1024 bytes. There is no maximum value. |
10. Click **Save**.
## Rewrite content rule examples
This table provides examples of rewrite content rule use cases and their results.
| Example description | Original content | Content type | Find criteria | Replacement value | Modified text |
| ----------------------------------------------------------------- | ------------------------------------------------ | ------------------ | --------------------- | ----------------- | ------------------------------------------------ |
| Rewrite URL portion of a web link | `` | `text/html` | `serverx.inside.corp` | `www.acme.com` | `` |
| Case-sensitive text replacement | ACMEcorp | `text/html` | Ecorp | `E Corporation` | ACME Corporation |
| Value masking | ```
{
"origin": "127.0.0.1, 192.168.1.1"
}
``` | `application/json` | `(127.0.0.1, ).*"` | `***********"` | ```
{
"origin": "127.0.0.1, ***********"
}
``` |
| Replacing text inside a specified element using Java regex groups | This text is **bold**. | `text/html` | `(bold)` | `not $1` | This text is not bold. |
| Case-insensitive text replacement using a Java regex match flag | HTTP | `text/html` | `(?i)http` | `FTP` | FTP |