---
title: "Create a project custom field"
method: POST
path: "/companies/{company}/projects/{project}/custom-fields"
tags: ["Projects"]
---

# Create a project custom field

`POST /companies/{company}/projects/{project}/custom-fields`

## Request

- Base URL: `https://api.factuarea.com/v1`
- URL: `https://api.factuarea.com/v1/companies/{company}/projects/{project}/custom-fields`
- Auth: one of:
  - HTTP bearer
  - API key in header `X-API-Key`

Define a custom field for the tasks of a project. `name` and `type` are required; `required`, `default_value` and `options` (for `dropdown` and `multiselect`) are optional. An inconsistent definition —options on a type that has none, a default that is not a valid value— returns 422 `invalid_custom_field_definition`. Existing tasks receive the default value.

## Path parameters

- `company` string, uuid, required
- `project` string, uuid, required

## Headers

- `Idempotency-Key` string
- `Factuarea-Version` string, date

## Request body

- CreateTaskCustomFieldV1Request
  - `name` string, required: Field name (1-60 characters; duplicate names are allowed within a project).
  - `type` string, required: Field type: `text`, `number`, `date`, `dropdown`, `boolean` or `multiselect`. Any other value returns 422 `invalid_custom_field_definition`.
  - `required` boolean: Whether the field is required; a required field needs a non-empty default value.
  - `default_value` union: Default value, applied to the existing tasks that have no value for the field: text, number, boolean, a `YYYY-MM-DD` date, an option or a list of options (`multiselect`).
    - string
    - number
    - boolean
    - string[]
  - `options` string[], nullable: Options of a `dropdown` (at least 1) or `multiselect` (at least 2, all different) field, up to 100.

## Response `201`

- object
  - `data` ProjectCustomField, required: A custom field defined for the tasks of a project.
    - `id` string, uuid, required: UUID v7 of the custom field.
    - `object` 'project_custom_field', required: Stripe-like discriminator. Always `project_custom_field` for this resource.
    - `project_id` string, uuid, required: UUID of the project.
    - `name` string, required: Field name, unique in the project.
    - `type` 'text' | 'number' | 'date' | 'dropdown' | 'boolean' | 'multiselect', required: Value type of the field.
    - `required` boolean, required: `true` when every task of the project must have a value.
    - `default_value` string, nullable, required: Value given to new tasks, serialized as a string (a JSON array for `multiselect`), or `null`.
    - `options` string[], required: Allowed values for `dropdown` and `multiselect`; empty for the other types.
    - `position` integer, required: Display order of the field.

## Other responses

- `400`: `parameter_unknown` with `subcode` `retired_active_profile_header`: the retired `X-Active-Profile` header was sent; the company goes in the path. `parameter_invalid_format` on `Factuarea-Version`: the header is not a `YYYY-MM-DD` date. `unsupported_api_version`: the `Factuarea-Version` date is not a supported version.
- `401`: Missing or invalid API key.
- `403`: The request is authenticated but not allowed: the API key lacks the required scope (`insufficient_scope`), the plan does not include the public API or this feature (`addon_not_active`, `feature_not_available_in_plan`), or the module is not available with a test key (`module_not_available_in_sandbox`).
- `404`: The requested resource does not exist or belongs to another company.
- `409`: The request conflicts with data that already exists or with a request running at the same time. `resource_conflict`: another request was reserving identifiers for the same kind of record at that moment and this one could not complete its reservation. Nothing was written; send the request again after a few seconds.
- `422`: Validation failed. The `error.param` field identifies which input is invalid.
- `429`: Rate limit exceeded. Retry after the duration in `Retry-After`.
- `500`: Unexpected server error.

---

[API](https://skmtc.dev/factuarea/apis/factuarea-public-api.md) · [All operations](https://skmtc.dev/factuarea/apis/factuarea-public-api/llms.txt) · [OpenAPI document](https://skmtc.dev/factuarea/apis/factuarea-public-api/revisions/718e77934422?raw)