--- title: List Custom Fields for a project slug: feature-experimentation/api/list-custom-fields-for-a-project docTags: createdAt: 2026-08-28T15:54:06.731Z --- { "id": "4rWcIJ94FQCIWJXyJPNfT", "type": "api-oas-v2", "data": { "method": "GET", "url": "https://api.optimizely.com/flags/v1//projects/{project_id}/custom_fields", "servers": [ { "url": "https://api.optimizely.com/flags/v1//projects/{project_id}/custom_fields" } ], "name": "List Custom Fields for a project", "description": "Get a list of Custom Fields within a Project.", "contentType": "application/json", "request": { "pathParameters": [ { "kind": "required", "name": "project_id", "type": "integer", "example": 12345, "description": "The project identifier" } ], "headerParameters": [], "queryParameters": [ { "kind": "optional", "name": "per_page", "type": "integer", "description": "The max number of items to include per page or results.", "format": "int64" }, { "kind": "optional", "name": "page_token", "type": "string", "description": "

Pagination page token. Implements prev, next, last, first

" }, { "kind": "optional", "name": "page_window", "type": "integer", "description": "

Number of previous and next page links to supply for the request (defaults to 1).

" }, { "kind": "optional", "name": "query", "type": "string", "description": "

Substring search across key, name and description (case-insensitive).

" }, { "kind": "optional", "name": "sort", "type": "array", "description": "Sort the custom fields based on the attributes from left to right.\n", "schema": [], "itemType": "string", "customType": "string[]" }, { "kind": "optional", "name": "archived", "type": "boolean", "description": "

Filter the custom fields by archived. A custom field can be either archived (archived=true) or unarchived (archived=false)

" }, { "kind": "optional", "name": "key", "type": "string", "description": "Filter the custom fields by key.\n" }, { "kind": "optional", "name": "entity_type", "type": "string", "description": "Filter the custom fields by entity type.\n", "enum": [ "flag", "rule" ] }, { "kind": "optional", "name": "field_type", "type": "string", "description": "Filter the custom fields by field type.\n", "enum": [ "text", "number", "boolean", "link", "label" ] } ], "bodyDataParameters": [], "formDataParameters": [], "oAuthParameters": [ { "id": "apiKey", "name": "apiKey", "kind": "optional", "type": "http", "scheme": "bearer" }, { "id": "OAuth2", "name": "OAuth2", "kind": "optional", "type": "oauth2", "description": "Write applications that authenticate with the REST API via OAuth 2.0.", "oauth2Flows": { "authorizationCode": { "authorizationUrl": "https://app.optimizely.com/oauth2/authorize", "tokenUrl": "https://app.optimizely.com/oauth2/token", "scopes": { "all": "Grants all access" } } }, "requiredScopes": [ "read", "write" ] } ], "cookieParameters": [] }, "responses": [ { "statusCode": "200", "description": "

Successful retrieval of a list of custom fields.

\n

The response includes RESTful JSON (https://restfuljson.org/) styled links. If a\nlink is not present in the response, it indicates a user is not authorized to access\nthe related resource.

", "jsonExample": "", "isExpanded": true, "schema": [ { "kind": "optional", "type": "object", "description": "", "customType": "CustomFieldsList", "schema": [ { "name": "count", "kind": "required", "type": "integer", "description": "Number of CustomFields on the current page.", "example": 2 }, { "name": "first_url", "kind": "required", "type": "object", "description": "Link to first page of CustomFields in a series.", "complexType": "allOf", "complexItems": [ { "name": "UrlValue", "description": "", "modelRef": "#/components/schemas/UrlValue", "schema": [] } ], "schema": [] }, { "name": "items", "kind": "required", "type": "array", "description": "Represents custom fields for entities\n", "modelRef": "#/components/schemas/CustomField", "customType": "CustomField[]", "schema": [ { "name": "archived", "kind": "optional", "type": "boolean", "description": "Whether the custom field is archived. New custom fields are created as unarchived by default.", "example": false }, { "name": "created_by_user_id", "kind": "optional", "type": "string", "readOnly": true, "nullable": true, "description": "

Identifier of the user who created this custom field (often an email).

", "example": "user@company.com" }, { "name": "created_time", "kind": "optional", "type": "string", "readOnly": true, "nullable": true, "description": "Timestamp when the custom field was created.", "example": "2024-01-01T10:00:00.000Z", "format": "date-time" }, { "name": "default_value", "kind": "optional", "type": "string", "description": "Default value for the custom field if applicable.", "example": "option1" }, { "name": "description", "kind": "optional", "type": "string", "description": "Optional detailed description explaining the purpose and context of this CustomField.\nHelps team members understand what this CustomField is measuring.\n", "example": "Custom field to tag experiments owned by the analytics team", "maxLength": 1000 }, { "name": "entity_type", "kind": "required", "type": "string", "description": "Type of entity the custom field is associated with", "example": "flag", "enum": [ "flag", "rule" ] }, { "name": "field_type", "kind": "required", "type": "string", "description": "

The type of the custom field (e.g., text, number, boolean, link, label)

", "example": "text", "enum": [ "text", "number", "boolean", "link", "label" ] }, { "name": "id", "kind": "required", "type": "integer", "readOnly": true, "description": "

System-generated unique identifier for the CustomField.

", "example": 12345 }, { "name": "key", "kind": "required", "type": "string", "description": "

Unique user-defined identifier for the CustomField within the project.\nMust contain only alphanumeric characters, underscores, and hyphens.

", "example": "analytics_team", "maxLength": 64, "pattern": "^[a-zA-Z0-9_\\-]+$" }, { "name": "name", "kind": "required", "type": "string", "description": "

Human-readable name for the CustomField displayed in the UI.

", "example": "Analytics Team", "maxLength": 255 }, { "name": "project_id", "kind": "optional", "type": "integer", "readOnly": true, "description": "The unique identifier of the project this CustomField belongs to.", "example": 98765, "format": "int64" }, { "name": "required", "kind": "required", "type": "boolean", "description": "Indicates if the custom field is required for the associated entity.", "example": false }, { "name": "updated_time", "kind": "optional", "type": "string", "readOnly": true, "description": "Timestamp when the custom field was last updated.", "example": "2024-01-01T10:00:00.000Z", "format": "date-time" }, { "name": "validation", "kind": "optional", "type": "object", "nullable": true, "description": "

Validation rules for the custom field if applicable.\nAllowed keys depend on field_type:

\n
    \n
  • text → max_length, regex
    • \n
  • number → min, max, decimal_places, use_thousand_separator
    • \n
  • label → field_options, allow_multi_select
    • \n
  • link → no validation fields
    • \n
  • boolean → no validation fields
    • \n
", "example": "{\"max\":100,\"max_length\":255,\"min\":1}", "schema": [ { "name": "allow_multi_select", "kind": "optional", "type": "boolean", "description": "Whether multiple values can be selected for label fields.", "example": false }, { "name": "decimal_places", "kind": "optional", "type": "integer", "description": "Number of allowed decimal places for numeric values.", "example": 2 }, { "name": "field_options", "kind": "optional", "type": "array", "description": "Allowed values for label fields.", "example": "[\"US\",\"EU\",\"APAC\"]", "itemType": "string", "customType": "string[]", "itemExample": "", "itemDefault": "" }, { "name": "max", "kind": "optional", "type": "number", "description": "Maximum value for number fields.", "example": 100 }, { "name": "max_length", "kind": "optional", "type": "integer", "description": "Maximum length for string fields.", "example": 255 }, { "name": "min", "kind": "optional", "type": "number", "description": "Minimum value for number fields.", "example": 1 }, { "name": "regex", "kind": "optional", "type": "string", "description": "Regular expression that the input must match.", "example": "^[A-Za-z0-9_-]+$" }, { "name": "use_thousand_separator", "kind": "optional", "type": "boolean", "description": "

Whether thousand separators should be permitted/displayed.

", "example": true } ] } ] }, { "name": "last_url", "kind": "required", "type": "object", "description": "Link to the last page of CustomFields in a series.", "complexType": "allOf", "complexItems": [ { "name": "UrlValue", "description": "", "modelRef": "#/components/schemas/UrlValue", "schema": [] } ], "schema": [] }, { "name": "next_url", "kind": "optional", "type": "object", "description": "

List of links to next pages of CustomFields in a series.

\n

The first element in the array is the exact next page after the current record, etc.

", "complexType": "allOf", "complexItems": [ { "name": "UrlList", "description": "", "modelRef": "#/components/schemas/UrlList", "schema": [] } ], "schema": [] }, { "name": "page", "kind": "required", "type": "integer", "description": "

Number of the current page. 1-index based.

", "example": 5 }, { "name": "prev_url", "kind": "optional", "type": "object", "description": "

List of links to previous pages of CustomFields in a series.

\n

The first element in the array is the exact previous page before the current record, etc.

", "complexType": "allOf", "complexItems": [ { "name": "UrlList", "description": "", "modelRef": "#/components/schemas/UrlList", "schema": [] } ], "schema": [] }, { "name": "total_count", "kind": "required", "type": "integer", "description": "Total number of CustomFields for this series.", "example": 20 }, { "name": "total_pages", "kind": "required", "type": "integer", "description": "Total number of pages for this series.", "example": 10 }, { "name": "url", "kind": "required", "type": "object", "description": "Link to self", "complexType": "allOf", "complexItems": [ { "name": "UrlValue", "description": "", "modelRef": "#/components/schemas/UrlValue", "schema": [] } ], "schema": [] } ], "modelRef": "#/components/schemas/CustomFieldsList", "isExpanded": true } ] }, { "statusCode": "400", "description": "Malformed requests and invalid parameter names and types", "jsonExample": "", "isExpanded": true }, { "statusCode": "401", "description": "Invalid credentials", "jsonExample": "", "isExpanded": true }, { "statusCode": "403", "description": "Do not have permission to perform the operation", "jsonExample": "", "isExpanded": true }, { "statusCode": "404", "description": "Not found. No content", "jsonExample": "", "isExpanded": true } ], "hasXCodeSamples": false, "examples": { "languages": [ { "id": "BQgWpGzAfD1U5-P4LzV3S", "language": "curl", "label": "cURL", "code": "curl --request GET \\\n --url https://api.optimizely.com/flags/v1//projects/{project_id}/custom_fields \\\n --header 'accept: application/json'" }, { "id": "aSEsWSmlzqHk3rEPNsA-L", "language": "javascript", "label": "javascript", "code": "var myHeaders = new Headers();\nmyHeaders.append(\"accept\", \"application/json\");\nmyHeaders.append(\"content-type\", \"application/json\");\n\nvar requestOptions = {\n method: 'GET',\n headers: myHeaders,\n redirect: 'follow'\n};\n\nfetch(\"https://api.optimizely.com/flags/v1//projects/{project_id}/custom_fields\", requestOptions)\n .then(response => response.text())\n .then(result => console.log(result))\n .catch(error => console.log('error', error));" }, { "id": "arh2D9YvT4_iI5VI-dlqM", "language": "ruby", "label": "Ruby", "code": "require \"uri\"\nrequire \"json\"\nrequire \"net/http\"\n\nurl = URI(\"https://api.optimizely.com/flags/v1//projects/{project_id}/custom_fields\")\n\nhttps = Net::HTTP.new(url.host, url.port)\nhttps.use_ssl = true\n\nrequest = Net::HTTP::Get.new(url)\nrequest[\"accept\"] = \"application/json\"\nrequest[\"content-type\"] = \"application/json\"\n\nresponse = https.request(request)\nputs response.read_body\n" }, { "id": "4bNYAJq-uJ5AJ3KRubkSF", "language": "python", "label": "Python", "code": "import requests\nimport json\n\nurl = \"https://api.optimizely.com/flags/v1//projects/{project_id}/custom_fields\"\n\npayload = {}\nheaders = {\n 'accept': 'application/json',\n 'content-type': 'application/json'\n}\n\nresponse = requests.request(\"GET\", url, headers=headers, data=payload)\n\nprint(response.text)\n" } ], "selectedLanguageId": "BQgWpGzAfD1U5-P4LzV3S" }, "results": { "languages": [ { "id": "response-0-200", "language": "200", "code": "// Successful retrieval of a list of custom fields.\nThe response includes RESTful JSON (https://restfuljson.org/) styled links. If a\nlink is not present in the response, it indicates a user is not authorized to access\nthe related resource.\n{\n \"count\": 2,\n \"first_url\": {},\n \"items\": [\n {\n \"archived\": false,\n \"created_by_user_id\": \"user@company.com\",\n \"created_time\": \"2024-01-01T10:00:00.000Z\",\n \"default_value\": \"option1\",\n \"description\": \"Custom field to tag experiments owned by the analytics team\",\n \"entity_type\": \"flag\",\n \"field_type\": \"text\",\n \"id\": 12345,\n \"key\": \"analytics_team\",\n \"name\": \"Analytics Team\",\n \"project_id\": 98765,\n \"required\": false,\n \"updated_time\": \"2024-01-01T10:00:00.000Z\",\n \"validation\": {\n \"allow_multi_select\": false,\n \"decimal_places\": 2,\n \"field_options\": [\n \"\"\n ],\n \"max\": 100,\n \"max_length\": 255,\n \"min\": 1,\n \"regex\": \"^[A-Za-z0-9_-]+$\",\n \"use_thousand_separator\": true\n }\n }\n ],\n \"last_url\": {},\n \"next_url\": {},\n \"page\": 5,\n \"prev_url\": {},\n \"total_count\": 20,\n \"total_pages\": 10,\n \"url\": {}\n}" }, { "id": "response-1-400", "language": "400", "code": "// Malformed requests and invalid parameter names and types\n" }, { "id": "response-2-401", "language": "401", "code": "// Invalid credentials\n" }, { "id": "response-3-403", "language": "403", "code": "// Do not have permission to perform the operation\n" }, { "id": "response-4-404", "language": "404", "code": "// Not found. No content\n" } ], "selectedLanguageId": "response-0-200" } }, "children": [ { "text": "" } ] }