---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/sendgrid/api-reference/contacts-api-custom-fields#article
headline: Contacts API - Custom Fields
description: Manage custom fields with the SendGrid Contacts API. Create, retrieve, and delete custom and reserved fields to store extra data about your contacts.
url: https://www.twilio.com/docs/sendgrid/api-reference/contacts-api-custom-fields
inLanguage: en
dateModified: 2026-07-02T23:18:59.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# Contacts API - Custom Fields

> \[!WARNING]
>
> This covers the obsolete Legacy Marketing Campaigns API.

> \[!NOTE]
>
> For the most up-to-date information on the Custom Fields API, please visit the [new Marketing Campaigns Custom Fields API](/docs/sendgrid/api-reference/custom-fields).

The Custom Fields API lets you create and manage custom fields for your contacts. Custom fields are used to store additional information about your contacts. For example, you might use custom fields to store a contact's birthday, their favorite color, or any other information that is relevant to your business.