# Sending custom field info via api

**URL:** <https://integration.keap.com/t/sending-custom-field-info-via-api/88606>\
**Category:** API Q&A\
**Created:** [August 30, 2022, 8:30am UTC](https://integration.keap.com/t/sending-custom-field-info-via-api/88606 "2022-08-30T08:30:28Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![Pav](https://sea1.discourse-cdn.com/flex019/user_avatar/integration.keap.com/pav/32/124_2.png) [@Pav](https://integration.keap.com/u/Pav)\
**Post date:** [August 30, 2022, 9:23am UTC](https://integration.keap.com/t/sending-custom-field-info-via-api/88606/2 "2022-08-30T09:23:54Z")

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Hi Andy, the question here is are you using REST (I guess it is this one) or XML-RPC to communicate with the API?

For REST, you can use this API call to retrieve the Contact Custom Fields to see the Id numbers.  
[https://developer.keap.com/docs/rest/#operation/retrieveContactModelUsingGET](https://developer.keap.com/docs/rest/#operation/retrieveContactModelUsingGET)

And example of sending custom fields is given in this discussion here:

> [@Update Contact Custom Field](https://integration.keap.com/t/update-contact-custom-field/546):
>
> I am trying to use the REST API to update a custom field for a contact. I have looked up the database name from Admin-\>Settings (customField) and have read that there needs to be an underscore preceding the database name (\_customField). The data type for my field is text. Here is the request I am sending to PATCH “[https://api.infusionsoft.com/crm/rest/v1/contacts/userId?access\_token=access\_token](https://api.infusionsoft.com/crm/rest/v1/contacts/userId?access_token=access_token)” (userID and access\_token values replaced of course) custom\_fields: [ { content: ‘test’, id: ‘\_…

For XML-RPC, you would have to prefix the custom field name with the underscore, but there is no Id Number.

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_[View the full topic](https://integration.keap.com/t/sending-custom-field-info-via-api/88606)._