> ## Documentation Index > Fetch the complete documentation index at: https://docs.migma.ai/llms.txt > Use this file to discover all available pages before exploring further. # Get Project Field Catalog > Returns subscriber field metadata for the project: which fields exist, how often each is populated (fillRate), example values, and whether the field is auto-filled at send time. Powers variable pickers, persona prefill, and template-coverage UIs. Optionally scope the result to a specific segment or tag. ## OpenAPI ````yaml /api-reference/openapi.json get /v1/projects/{projectId}/field-catalog openapi: 3.1.0 info: title: Migma.ai API (v1) description: >- API for managing brands, contacts, email generation, sending, and integrations. license: name: MIT version: 1.0.0 servers: - url: https://api.migma.ai description: Production security: - apiKeyAuth: [] tags: - name: Projects/Brands description: Manage projects (brands) and import from websites - name: Contacts description: Manage your contacts, segments, tags, and topics - name: Segments description: Create and manage dynamic contact segments - name: Tags description: Organize contacts with tags - name: Topics description: Manage subscription topics and preferences - name: Emails description: Generate, send, and export emails - name: Email Validation description: Validate email content for compatibility and deliverability - name: Email Previews description: Preview emails across devices and email clients - name: Domains description: Manage sending domains and verification - name: Webhooks description: Manage webhook endpoints for real-time event notifications - name: Events description: Record customer events and conversions - name: Integrations description: Third-party platform integrations - name: Campaigns description: Create, schedule, send, and manage email campaigns - name: Project Editing description: Edit project assets, logos, images, and knowledge base entries paths: /v1/projects/{projectId}/field-catalog: get: tags: - Projects/Brands summary: Get Project Field Catalog description: >- Returns subscriber field metadata for the project: which fields exist, how often each is populated (fillRate), example values, and whether the field is auto-filled at send time. Powers variable pickers, persona prefill, and template-coverage UIs. Optionally scope the result to a specific segment or tag. operationId: GetProjectFieldCatalog parameters: - name: projectId in: path description: Project ID (MongoDB ObjectId) required: true schema: type: string pattern: ^[0-9a-fA-F]{24}$ - name: segmentId in: query description: Restrict the catalog to subscribers in this segment. required: false schema: type: string pattern: ^[0-9a-fA-F]{24}$ - name: tag in: query description: Restrict the catalog to subscribers with this tag id. required: false schema: type: string pattern: ^[0-9a-fA-F]{24}$ responses: '200': description: Field catalog response content: application/json: schema: $ref: '#/components/schemas/ApiResponseFieldCatalog' '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/Forbidden' '404': $ref: '#/components/responses/NotFound' x-codeSamples: - lang: javascript label: Node.js SDK source: >- import Migma from 'migma'; const migma = new Migma('YOUR_API_KEY'); const { data, error } = await migma.projects.fieldCatalog('PROJECT_ID'); // Scope to a segment or tag: // await migma.projects.fieldCatalog('PROJECT_ID', { segmentId: 'SEGMENT_ID' }); // await migma.projects.fieldCatalog('PROJECT_ID', { tag: 'TAG_ID' }); components: schemas: ApiResponseFieldCatalog: allOf: - $ref: '#/components/schemas/ApiResponse' - type: object properties: data: $ref: '#/components/schemas/FieldCatalogResponse' ApiResponse: type: object properties: success: type: boolean data: nullable: true error: type: string nullable: true required: - success FieldCatalogResponse: type: object properties: entries: type: array items: $ref: '#/components/schemas/FieldCatalogEntry' totalSubscribers: type: integer description: Total subscribers in the scoped set the catalog was computed over. computedAt: type: string format: date-time description: When the catalog was computed. Catalogs are cached for up to 1 hour. required: - entries - totalSubscribers - computedAt ApiError: type: object properties: success: type: boolean default: false error: type: string code: type: string description: >- Machine-readable error code (e.g., IDEMPOTENCY_CONFLICT, DOMAIN_CLAIMABLE). data: type: object description: >- Additional structured context for the error, such as the affected domain. additionalProperties: true required: - success - error FieldCatalogEntry: type: object description: >- A single subscriber field discovered in the project, with its fill rate and example values. properties: key: type: string description: Stable slug used in templates (e.g. firstName, company). label: type: string description: Human-readable label for UI. type: type: string enum: - string - number - boolean - date - url - unknown description: >- Inferred value type. V1 returns 'string' for everything; future passes will infer richer types. fillRate: type: number minimum: 0 maximum: 1 description: Share of subscribers in the scope with a non-empty value (0–1). sample: type: array items: type: string description: >- Up to 3 example values, each truncated to 50 characters. Empty for auto fields. auto: type: boolean description: >- True for native fields auto-filled at send time (email, firstName, etc.). required: - key - label - type - fillRate - sample - auto responses: Unauthorized: description: Unauthorized content: application/json: schema: $ref: '#/components/schemas/ApiError' Forbidden: description: Forbidden - Missing required permissions or access denied content: application/json: schema: $ref: '#/components/schemas/ApiError' NotFound: description: Resource not found content: application/json: schema: $ref: '#/components/schemas/ApiError' securitySchemes: apiKeyAuth: type: apiKey in: header name: Authorization description: >- API key authentication. Use 'Authorization: Bearer YOUR_API_KEY' where YOUR_API_KEY is obtained from the Migma dashboard under Settings → Developers → API Keys. ````