> For the complete documentation index, see [llms.txt](https://docs.helmut.de/helmut4-releases/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.helmut.de/helmut4-releases/helmut4-components/streamdesigner/nodes/actions/misc-21/regex-apply-action.md).
# Regex Apply Action
The **Regex Apply Action** node modifies a string by applying a regular expression (REGEX).
It evaluates the provided string, searches for matches using the defined regex pattern, and replaces the matching characters with a specified replacement value. The corrected string can then be reused in the workflow.
This node is commonly used to normalize names (e.g., project names, filenames, or metadata) so they meet naming conventions or filesystem restrictions.
#### Input Parameters
**String**\
The source string to be processed (for example [{project.name}](/helmut4-releases/helmut4-components/streamdesigner/wildcards/project-related-wildcards-27/project-name.md)).
**Regex**\
The regular expression used to find characters or patterns inside the string.\
Example: `[^a-zA-Z0-9_-]+` finds all characters that are not letters, numbers, underscores, or hyphens.
**Replace With**\
The character(s) that will replace all matches found by the regex.\
If left empty, matching characters will be removed.
Regex Apply Action
#### Output and Wildcards
The processed string is returned as the node result and can be accessed via:
* [{stream.last\_result}](/helmut4-releases/helmut4-components/streamdesigner/wildcards/result-or-return-wildcards-2/stream-last_result.md)
* [{node.result.?}](/helmut4-releases/helmut4-components/streamdesigner/wildcards/result-or-return-wildcards-2/node-result.md)
The value can then be used in later nodes (e.g., folder creation, file naming, or metadata).
#### Behavior
* Reads a string input
* Applies the regex pattern
* Replaces all matches
* Returns the modified string
* Supports asynchronous execution
#### Typical Use Cases
* sanitizing project or folder names
* creating filesystem-safe filenames
* enforcing naming conventions
* removing forbidden characters
* preparing metadata for external systems
#### Example
Source string:
```
My Project: Episode #01 (Final!)
```
Regex:
```
[^a-zA-Z0-9_-]+
```
Replace with:
```
_
```
Result:
```
My_Project_Episode_01_Final_
```
#### Practical Tip
This node is especially useful before **file or folder creation**.\
Many storage systems, playout servers, and external integrations reject special characters — cleaning the string early prevents hard-to-debug downstream workflow failures.
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