---
title: "Get Project Field Catalog"
method: GET
path: "/v1/projects/{projectId}/field-catalog"
tags: ["Projects/Brands"]
---

# Get Project Field Catalog

`GET /v1/projects/{projectId}/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.

## Path parameters

- `projectId` string, required

## Query parameters

- `segmentId` string
- `tag` string

## Response `200`

Field catalog response

- ApiResponseFieldCatalog
  - `success` boolean, required
  - `data` object, nullable
    - `entries` FieldCatalogEntry[], required
      - `key` string, required — Stable slug used in templates (e.g. firstName, company).
      - `label` string, required — Human-readable label for UI.
      - `type` 'string' | 'number' | 'boolean' | 'date' | 'url' | 'unknown', required — Inferred value type. V1 returns 'string' for everything; future passes will infer richer types.
      - `fillRate` number, required — Share of subscribers in the scope with a non-empty value (0–1).
      - `sample` string[], required — Up to 3 example values, each truncated to 50 characters. Empty for auto fields.
      - `auto` boolean, required — True for native fields auto-filled at send time (email, firstName, etc.).
    - `totalSubscribers` integer, required — Total subscribers in the scoped set the catalog was computed over.
    - `computedAt` string, date-time, required — When the catalog was computed. Catalogs are cached for up to 1 hour.
  - `error` string, nullable

## Other responses

- `401` — Unauthorized
- `403` — Forbidden - Missing required permissions or access denied
- `404` — Resource not found

---

[API](https://skmtc.net/migma/apis/migma-ai-api-v1.md) · [All operations](https://skmtc.net/migma/apis/migma-ai-api-v1/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/migma/migma-ai-api-v1/revisions/2d06ad0e0bc3/schema)