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

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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).

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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

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"},
)

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)

{
  "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

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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}

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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.

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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

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Utility Scripts

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