---
title: "List Available Feature Extractors"
method: GET
path: "/v1/discovery/extractors"
tags: ["Discovery"]
---

# List Available Feature Extractors

`GET /v1/discovery/extractors`

Discover all available feature extractors with their capabilities, supported modalities, output features, and example usage. Use this to understand what extractors are available when configuring namespaces and collections in manifests.

## Response `200`

Successful Response

- ExtractorDiscovery[]
  - `name` string, required — Feature extractor name (e.g., 'multimodal_extractor')
  - `version` string, required — Feature extractor version (e.g., 'v1')
  - `description` string, required — Human-readable description of what this extractor does
  - `supported_modalities` string[] — List of supported input modalities (text, image, video, audio)
  - `output_features` object[] — List of features produced by this extractor
  - `input_schema` object, nullable — JSON Schema for extractor inputs — what fields the extractor reads from source objects
  - `parameter_schema` object, nullable — JSON Schema for tunable parameters (defaults, ranges, descriptions for every knob)
  - `output_schema` object, nullable — JSON Schema for output documents — what fields appear in extracted documents
  - `costs` CostsInfo — Credit cost information for a feature extractor. Describes the pricing tier and standardized cost rates for using this extractor. Rates are defined using CostUnit types that align with extractor input types.
    - `tier` integer, required — Cost tier (1-4): 1=SIMPLE, 2=MODERATE, 3=COMPLEX, 4=PREMIUM
    - `tier_label` string, required — Human-readable tier label (SIMPLE, MODERATE, COMPLEX, PREMIUM)
    - `rates` CostRate[], required — List of cost rates for different input types this extractor processes
      - `unit` 'minute' | 'image' | '1k_tokens' | 'page' | 'face' | 'extraction', required — Standard billing units aligned with extractor input types. Each unit represents a measurable quantity that extractors process: - MINUTE: Video/audio duration in minutes - IMAGE: Per image processed - TOKENS_1K: Text tokens in thousands - PAGE: Document pages (PDF, etc.) - FACE: Detected faces in images/video - EXTRACTION: Flat per-operation cost
      - `credits_per_unit` integer, required — Number of credits charged per unit
      - `description` string, nullable — Human-readable description of what this rate covers
  - `type_mode` string, nullable — What input types this extractor can handle: 'type_specific' (only one type, e.g. video-only) or 'multimodal' (handles multiple types with conditional processing). Type-specific extractors cannot use automatic-typed bucket properties.
  - `expected_input_types` object, nullable — For type-specific extractors: maps input keys to required types (e.g., {'video': 'video', 'thumbnail': 'image'}). For multimodal extractors: null.
  - `inference_type` string, nullable — Kind of real-time inference this extractor provides: 'embedding', 'rerank', 'classify', 'generate', or 'general'. Determines which retriever stages are compatible. Null if the extractor is batch-only.
  - `supported_input_types` string[] — Accepted input types (e.g., ['video', 'image'])
  - `max_inputs` object — Maximum number of inputs per type (e.g., {'video': 1})
  - `default_parameters` object — Default parameter values — use as a starting point for tuning
  - `required_vector_indexes` object[], nullable — Vector indexes produced by this extractor (name, dimensions, distance metric, feature_uri)
  - `position_fields` string[] — Fields that uniquely identify each output document within a source object
  - `capabilities` string[] — What this extractor can do: 'batch' (feature extraction during ingestion), 'realtime' (query-time inference for retriever stages)
  - `example_usage` object — Minimal working configuration for namespace + collection + input_mappings + parameters

## Other responses

- `400` — Bad Request
- `401` — Unauthorized
- `403` — Forbidden
- `404` — Not Found
- `500` — Internal Server Error

---

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