Didit Face Match API

Overview

Compares two facial images to determine if they belong to the same person. Returns a similarity score (0-100).

Key constraints:

• Supported formats: JPEG, PNG, WebP, TIFF
• Maximum file size: 5MB per image
• If multiple faces in an image, the largest face is used for comparison
• Both user_image and ref_image are required

Capabilities: Similarity scoring, age estimation, gender detection, face bounding boxes, configurable decline threshold, optional image rotation for non-upright faces.

API Reference: https://docs.didit.me/standalone-apis/face-match Feature Guide: https://docs.didit.me/core-technology/face-match/overview

Authentication

All requests require x-api-key header. Get your key from Didit Business Console → API & Webhooks, or via programmatic registration (see below).

Getting Started (No Account Yet?)

If you don't have a Didit API key, create one in 2 API calls:

1. Register: POST https://apx.didit.me/auth/v2/programmatic/register/ with {"email": "you@gmail.com", "password": "MyStr0ng!Pass"}
2. Check email for a 6-character OTP code
3. Verify: POST https://apx.didit.me/auth/v2/programmatic/verify-email/ with {"email": "you@gmail.com", "code": "A3K9F2"} → response includes api_key

To add credits: GET /v3/billing/balance/ to check, POST /v3/billing/top-up/ with {"amount_in_dollars": 50} for a Stripe checkout link.

See the didit-verification-management skill for full platform management (workflows, sessions, users, billing).

Endpoint

POST https://verification.didit.me/v3/face-match/

Headers

| Header | Value | Required | |---|---|---| | x-api-key | Your API key | Yes | | Content-Type | multipart/form-data | Yes |

Request Parameters (multipart/form-data)

| Parameter | Type | Required | Default | Constraints | Description | |---|---|---|---|---|---| | user_image | file | Yes | — | JPEG/PNG/WebP/TIFF, max 5MB | User's face image to verify | | ref_image | file | Yes | — | Same as above | Reference image to compare against | | face_match_score_decline_threshold | integer | No | 30 | 0-100 | Scores below this = Declined | | rotate_image | boolean | No | false | — | Try 0/90/180/270 degree rotations to find upright face | | save_api_request | boolean | No | true | — | Save in Business Console Manual Checks | | vendor_data | string | No | — | — | Your identifier for session tracking |

Example

python
import requests

response = requests.post(
    "https://verification.didit.me/v3/face-match/",
    headers={"x-api-key": "YOUR_API_KEY"},
    files={
        "user_image": ("selfie.jpg", open("selfie.jpg", "rb"), "image/jpeg"),
        "ref_image": ("id_photo.jpg", open("id_photo.jpg", "rb"), "image/jpeg"),
    },
    data={"face_match_score_decline_threshold": "50"},
)

typescript
const formData = new FormData();
formData.append("user_image", selfieFile);
formData.append("ref_image", referenceFile);
formData.append("face_match_score_decline_threshold", "50");

const response = await fetch("https://verification.didit.me/v3/face-match/", {
  method: "POST",
  headers: { "x-api-key": "YOUR_API_KEY" },
  body: formData,
});

Response (200 OK)

json
{
  "request_id": "a1b2c3d4-...",
  "face_match": {
    "status": "Approved",
    "score": 80,
    "user_image": {
      "entities": [
        {"age": 27.63, "bbox": [40, 40, 100, 100], "confidence": 0.717, "gender": "male"}
      ],
      "best_angle": 0
    },
    "ref_image": {
      "entities": [
        {"age": 22.16, "bbox": [156, 234, 679, 898], "confidence": 0.717, "gender": "male"}
      ],
      "best_angle": 0
    },
    "warnings": []
  },
  "created_at": "2025-05-01T13:11:07.977806Z"
}

Status Values & Handling

| Status | Meaning | Action | |---|---|---| | "Approved" | Score >= threshold | Faces match — proceed | | "Declined" | Score < threshold or no face | Check warnings for details. May need better image | | "In Review" | Needs manual review | Wait for review or retrieve via session API |

Error Responses

| Code | Meaning | Action | |---|---|---| | 400 | Invalid request | Check file format, size, parameters | | 401 | Invalid API key | Verify x-api-key header | | 403 | Insufficient credits | Top up at business.didit.me |

Response Field Reference

| Field | Type | Description | |---|---|---| | status | string | "Approved", "Declined", "In Review" | | score | integer | 0-100 similarity score (higher = more similar). null if no face found | | entities[].age | float | Estimated age | | entities[].bbox | array | Face bounding box [x1, y1, x2, y2] | | entities[].confidence | float | Face detection confidence (0-1) | | entities[].gender | string | "male" or "female" | | best_angle | integer | Best rotation angle for the face | | warnings | array | {risk, log_type, short_description, long_description} |

Warning Tags

| Tag | Description | Auto-Decline | |---|---|---| | NO_REFERENCE_IMAGE | Reference or face image missing | Yes | | NO_FACE_DETECTED | No face detected in one or both images | Yes | | LOW_FACE_MATCH_SIMILARITY | Score below threshold — potential identity mismatch | Configurable |

> Security best practice: Only store the status and score. Minimize biometric image data on your servers. Image URLs (in workflow mode) expire after 60 minutes.

Score Interpretation

| Score Range | Interpretation | Action | |---|---|---| | 90-100 | Very high confidence — same person | Auto-approve | | 70-89 | High confidence — likely same person | Approve (default threshold 30) | | 50-69 | Moderate — possible match | Consider manual review | | 30-49 | Low — likely different people | Declined at default threshold | | 0-29 | Very low — different people | Declined |

Utility Scripts

bash
export DIDIT_API_KEY="your_api_key"

python scripts/match_faces.py selfie.jpg id_photo.jpg
python scripts/match_faces.py selfie.jpg id_photo.jpg --threshold 50 --rotate