> For the complete documentation index, see [llms.txt](https://docs.antsomi.com/cdp-365-user-guide-en/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.antsomi.com/cdp-365-user-guide-en/marketing-hub/customer-journeys/custom-function.md).
# Custom Function
Custom functions help you customize personalized content using calculation formulas and determine the type and format of data displayed in the content.
## Create New Custom Function
**Step 1:** On Create/ Edit Customer Journey screen, click on icon **Personalization** and select **Add Personalization**.
**Step 2:** On **Add Personalization** pop up, click on **Personalization type** dropdown, select **Custom**.
**Step 3:** Enter custom function name in **Personalization Name** field. You can also click on Personalization Name field and select previously created custom functions from the suggestion list
**Step 4:** Insert you function you want into **Function** field.
***Note:** Only support **JSON** function.*
**Step 5:** Choose the appropriate data type and display style for your function in the Out put Data Type field and Output Format
**Step 6:** Optional, if you want to reuse this function, you can save as this function become a template by check on **Save as template** checkbox.
***Note:** After saving as a template, your function will display in the list of suggestions when clicked and enter the function name in the **Personalization name** field.*
**Step 7:** Click **Insert** to add your function into Content. After click, your function will display as tag
## Edit Custom Function
If you want to edit your function, you can click on **function's tag**. Add Personalization pop up will display and you can edit your function. After editing, click **Update** to update the edited content.
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