> For the complete documentation index, see [llms.txt](https://docs.onum.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.onum.com/pipelines/actions/transformation/field-transformation/field-transformation-operations/compression/zlib-compress.md).

# Zlib Compress

## Description

This operation compresses data using the zlib compression algorithm and outputs the result as a base64-encoded string.

***

## Data types

These are the input/output expected data types for this operation:

### Input data

`String` - Data to compress.

### Output data

`String` - Base64-encoded compressed data.

***

## Parameters

These are the parameters you need to configure to use this operation (mandatory parameters are marked with a <mark style="color:red;">**\***</mark>):

<details>

<summary>Compression Level<mark style="color:red;"><strong>*</strong></mark></summary>

Choose a compression level from `-1` (default and recommended compression) to `9` (best compression, slower speed).

The default value is `-1`.

</details>

<details>

<summary>Output Format</summary>

Choose the required output format of your data between **Base64** (default) or **Hex**.

</details>

***

## Example

Suppose you want to **compress** a series of strings using the **zlib compression algorithm**. To do it:

1. In your Pipeline, open the required [Action](/pipelines/actions.md) configuration and select the input **Field**.
2. In the **Operation** field, choose **Zlib Compress**.
3. Set **Compression Level** to **-1**.
4. Set **Output Format** to **Base64**.
5. Give your **Output field** a name and click **Save**. You'll get the division results. For example:

```
Hello, World! -> eJzySM3JyVcozy/KSQEEAAuUAw0=
```

{% hint style="info" %}
You can try out operations with specific values using the **Input** field above the operation. You can enter the value in the example above and check the result in the **Output** field.
{% endhint %}