# Custom Fields

Extend contact and company records with custom data fields. Store any additional information relevant to your workflow.

**Limits:** Maximum 100 custom fields per object type (`lead` or `company`). Field names must start with a letter or underscore, and contain only alphanumeric characters and underscores.


## List custom fields

 - [GET /leads/api/custom-fields](https://api.grinfi.io/openapi/custom-fields/listcustomfields.md): Retrieve all custom field definitions for contacts and companies.

## Create a custom field

 - [POST /leads/api/custom-fields](https://api.grinfi.io/openapi/custom-fields/createcustomfield.md): Define a new custom field for contacts or companies.

## Update a custom field

 - [PUT /leads/api/custom-fields/{uuid}](https://api.grinfi.io/openapi/custom-fields/updatecustomfield.md): Update a custom field's name or order.

## Delete a custom field

 - [DELETE /leads/api/custom-fields/{uuid}](https://api.grinfi.io/openapi/custom-fields/deletecustomfield.md): Permanently remove a custom field definition and all its values.

## Set a custom field value

 - [POST /leads/api/custom-field-values](https://api.grinfi.io/openapi/custom-fields/upsertcustomfieldvalue.md): Set (or update) a custom field value on a contact or company. Pass null as value to clear the field.