> ## Documentation Index
> Fetch the complete documentation index at: https://help.retainful.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Custom fields

> Store extra information on every contact and use it for personalization and segmentation.

Custom fields let you store information Retainful doesn't track by default — anything from a customer's shoe size to their loyalty tier.

## Create a custom field

1. Go to **Settings → Custom Fields**.
2. Click **Add field**, name it, and choose its type:

| Type         | Use for                                    |
| ------------ | ------------------------------------------ |
| **Text**     | Free-form values like "favorite color".    |
| **Number**   | Quantities like loyalty points.            |
| **Date**     | Birthdays, renewal dates.                  |
| **Boolean**  | Yes/no flags like "wholesale customer".    |
| **Dropdown** | A fixed set of options like T-shirt sizes. |

## How fields get filled

* **Imports** — map CSV columns to custom fields in the [import wizard](/audience/import-contacts).
* **Signup forms** — add a question to your form and store the answer in a field.
* **Manually** — edit any contact's profile.
* **API** — send `custom_properties` when [creating contacts](/developers/api/contacts) from your own systems.
* **Store sync** — some platform data (like tags) arrives as properties automatically.

## Using custom fields

### Personalization

Insert any field into your emails with merge tags — "Hi Jane, your **Gold** membership renews soon." See [Personalization](/campaigns/personalization).

### Segmentation

Filter on custom fields in the [segment builder](/audience/segments) — for example, everyone whose "loyalty\_tier" is "Gold" and who hasn't ordered this quarter.

### Automation branching

Use a field in a **Binary** step to send different emails to different groups inside one automation.

<Tip>
  Keep field names consistent and lowercase (like `loyalty_tier`, not "Loyalty Tier!") — it keeps imports, API calls, and segments tidy as your usage grows.
</Tip>