> ## Documentation Index > Fetch the complete documentation index at: https://docs.prophia.com/llms.txt > Use this file to discover all available pages before exploring further. # GET Custom Field > Returns a single Building Custom Field by id, with its options. **Required capabilities:** `READ:CUSTOM_FIELD` ## OpenAPI ````yaml /api-reference/openapi.json get /rest/v2/accounts/{accountId}/custom-fields/{fieldId} openapi: 3.1.0 info: title: Prophia API Documentation license: name: Apache 2.0 url: http://springdoc.org version: v2.495.0 servers: - url: https://api.prophia.com description: Prophia API security: - apiKey: [] tags: - name: Accounts description: >- Accounts are the top-level scope for everything in the API. Start here: list your accounts to find the `accountId` every other path requires. - name: Properties description: >- Properties group one or more buildings under a single asset within an account. - name: Buildings description: Buildings are the physical structures where leases and spaces live. - name: Building Spaces description: >- Building spaces are the units inside a building — suites, floors, storage. A space's `suiteNumber` is the canonical name that tag `applicableSpaces` entries reference by string match. - name: Leases description: >- Leases are the agreements occupying building spaces. Each lease carries its source documents and the tags (structured terms) extracted from them. - name: Documents description: >- Documents are the source files attached to leases — original leases, amendments, memorandums, etc. - name: Tags description: >- Tags are the structured lease terms Prophia extracts from documents — a rent amount, a renewal option, a key date — each cited to its location in the source document. STANDARD tags carry a typed `value`; COMPLEX tags carry option details in `tagComponents`. - name: Custom Terms description: >- Custom terms are account-level definitions of extra lease terms your team tracks beyond Prophia's standard set. Tags created from them are ordinary tags with `isCustomTag: true` — the definition and its tag instances are separate resources. - name: Custom Fields description: >- Custom Fields are Account-level fields your team tracks on Buildings beyond Prophia's standard set. A `SINGLE` field holds free text per Building; a `MULTI` field holds one of a fixed list of options. Assignments set a field's value on a Building. - name: Loans description: >- Loans are the financing agreements secured by an account's buildings. Each loan carries its source documents and the terms read from them: summary terms, covenants and reporting deliverables. Loans is a Labs feature in beta, and its endpoints may change. x-beta: true paths: /rest/v2/accounts/{accountId}/custom-fields/{fieldId}: get: tags: - Custom Fields summary: GET Custom Field description: |- Returns a single Building Custom Field by id, with its options. **Required capabilities:** `READ:CUSTOM_FIELD` operationId: getCustomField parameters: - name: accountId in: path required: true schema: type: string - name: fieldId in: path required: true schema: type: string responses: '200': description: OK content: '*/*': schema: $ref: '#/components/schemas/V2CustomFieldModel' '400': description: >- Invalid input — for example an unknown `include` key or a malformed parameter value content: application/json: schema: $ref: '#/components/schemas/V2ErrorResponse' example: error: Invalid Input errorCode: InvalidInput message: >- Unknown include keys: [bogus]; supported: [tags, documents, subleases] status: 400 BAD_REQUEST timestamp: '2026-09-02T20:41:03.118Z' localizedMessage: >- Unknown include keys: [bogus]; supported: [tags, documents, subleases] '401': description: >- The credential was rejected before the request reached the endpoint — for example a JWT was presented where an API key is required. Only `error` is populated on this path content: application/json: schema: $ref: '#/components/schemas/V2ErrorResponse' example: error: JWT authentication is not supported. Use an API key. '403': description: >- The API key is valid but lacks a required capability, or its building permissions do not cover the requested resource. The message names the missing capabilities only in the former case content: application/json: schema: $ref: '#/components/schemas/V2ErrorResponse' example: error: Access Denied errorCode: AccessDenied message: 'Not authorized. Missing capabilities: READ:TAG' status: 403 FORBIDDEN timestamp: '2026-09-02T20:41:03.118Z' localizedMessage: 'Not authorized. Missing capabilities: READ:TAG' '404': description: No such resource is visible to the account named in the path content: application/json: schema: $ref: '#/components/schemas/V2ErrorResponse' example: error: Entity Not Found errorCode: EntityNotFound message: This entity is not found in the system. status: 404 NOT_FOUND timestamp: '2026-09-02T20:41:03.118Z' localizedMessage: This entity is not found in the system. components: schemas: V2CustomFieldModel: type: object description: >- An Account-level field your team tracks on Buildings beyond Prophia's standard set. properties: id: type: string description: Prophia internal Custom Field ID (UUID). readOnly: true accountId: type: string description: The UUID for the Account this Custom Field belongs to. readOnly: true fieldName: type: string description: Name of the field. fieldType: type: string description: >- `SINGLE` fields hold free text per Building. `MULTI` fields hold one of a fixed list of `options`. enum: - SINGLE - MULTI readOnly: true active: type: boolean description: Whether the field is shown on Buildings. options: type: array description: The field's current options. items: $ref: '#/components/schemas/V2CustomFieldOptionModel' readOnly: true createdBy: type: string description: The user who created the field. readOnly: true createdAt: type: string format: date-time description: When the field was created. readOnly: true updatedAt: type: string format: date-time description: When the field was last modified. readOnly: true V2ErrorResponse: type: object properties: error: type: string description: Stable error category example: Invalid Input errorCode: type: string description: Stable error code suitable for programmatic handling example: InvalidInput message: type: string description: Human-readable detail; may aggregate multiple field errors status: type: string description: >- HTTP status of the response as code and reason phrase, matching the response's own status line example: 404 NOT_FOUND timestamp: type: string format: date-time description: When the error was produced, as an ISO-8601 UTC instant example: '2026-09-02T20:41:03.118Z' localizedMessage: type: string description: >- Same text as `message`; present because the body is a serialized exception. Prefer `message` V2CustomFieldOptionModel: type: object description: >- A value of a Building Custom Field. On `MULTI` fields these are the fixed choices; on `SINGLE` fields they are the distinct values assigned to Buildings. properties: id: type: string description: Prophia internal Custom Field Option ID (UUID). readOnly: true value: type: string description: The option's value. createdAt: type: string format: date-time description: When the option was created. readOnly: true updatedAt: type: string format: date-time description: When the option was last modified. readOnly: true securitySchemes: apiKey: type: apiKey description: >- Prophia API key — either an account key (grants admin level permissions) or a user key with the REST scope. Send it in the `X-API-Key` header, or equivalently as `Authorization: Bearer `. JWTs are rejected on /rest endpoints with 401. name: X-API-Key in: header ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.