License Plate OCR API

Deploy automated license plate recognition (ALPR) built for global scale. Our engine transcends generic models by accurately extracting native scripts worldwide—from Arabic and Cyrillic to complex Asian characters—preserving exact layouts and regional nuances. It natively supports multi-plate detection (e.g., stacked trailer and prime mover plates) and dual-language semantic parsing. Beyond the primary plate number, the API identifies plate color, vehicle type, and infers country/region to power border crossings, tolling, and global logistics workflows.

Endpoint

POSThttps://api.structocr.com/v1/license-plate

Request Parameters

Important: This endpoint requires application/json Content-Type. Images must be sent as Base64 strings.

Parameter	In	Required	Description
x-api-key	Header	Required	Your unique API key generated from the dashboard.
Content-Type	Header	Required	Must be set to `application/json`.
img	Body	Required	The Base64 encoded string of the vehicle/plate image. Supports standard Data URI (e.g., `data:image/jpeg;base64,...`) Supports raw Base64 strings Max file size: 4.5MB Formats: JPG, PNG, WebP, PDF Other decoded formats return `415 UNSUPPORTED_FILE_FORMAT`. For best response time, compress to under 300 KB.

Response Schema

The following attributes are extracted into the data object. The engine preserves native characters and utilizes strict enums for structural data.

Field	Type	Description
plates	array of objects	Array containing all detected plates on the vehicle (supports multi-plate layouts like trailers).
↳ plate_number	string \| null	The exact visual text including local scripts and original punctuation. Null if unreadable.
↳ plate_number_normalized	string \| null	Standardized Latin/ASCII version (uppercase letters, digits, spaces, hyphens) for database indexing.
↳ plate_color	enum	Dominant background color: white, yellow, black, green, blue, red, other, unknown.
↳ plate_type	enum	Vehicle type category: private, commercial, government, trailer, etc.
region_text	string \| null	Secondary caption (e.g., province/state), usually in the local native script.
country_guess	string \| null	Guessed country based on visual cues or unambiguous national format logic.
confidence_score	number	Recognition certainty level, returned as a decimal between 0.0 and 1.0.

Code Examples

Request Implementation

curl -X POST https://api.structocr.com/v1/license-plate \
  -H "Content-Type: application/json" \
  -H "x-api-key: YOUR_API_KEY" \
  -d '{
    "img": "data:image/jpeg;base64,/9j/4AAQSkZJRg..."
  }'

Success Response (200 OK)

JSON EXAMPLE

{
  "success": true,
  "data": {
    "plates": [
      {
        "plate_number": "7 SAM 123",
        "plate_number_normalized": "7SAM123",
        "plate_color": "white",
        "plate_type": "private"
      }
    ],
    "region_text": "California",
    "country_guess": "United States",
    "confidence_score": 0.99
  }
}

Live API Test

Live Demo: License Plate OCR Scanner

No registration required. Upload a file to test the extraction.

Upload

Results

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JPG · PNG · WebP · up to 500 files · max 4.5 MB each

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Error Responses

400 Bad Request - Invalid Input

{
  "status": 400,
  "code": "INVALID_REQUEST_FORMAT",  
  "message":"The image data in 'img' field is malformed. Please check for illegal characters or incorrect Base64 encoding."
}

402 Payment Required - Insufficient Credits

{
  "status": 402,
  "code": "INSUFFICIENT_CREDITS",
  "message": "Your account balance is insufficient to complete this operation."
}

413 Payload Too Large

The Base64 decoded image size exceeds 4.5MB.

{
  "error": "FILE_TOO_LARGE"
}

415 Unsupported Media Type

{
  "error": "INVALID_CONTENT_TYPE_USE_JSON"
}

422 Unprocessable Entity - Policy Violation

{
  "status": 422,
  "code": "CONTENT_POLICY_VIOLATION",
  "message": "The document content could not be processed due to safety policies."
}

500 Internal Server Error

{
  "status": 500,
  "code": "PROCESSING_ERROR",
  "message": "An internal error occurred while processing the document..."
}

503 Service Unavailable - System Busy

{
  "status": 503,
  "code": "SYSTEM_BUSY",
  "message": "StructOCR is currently processing a high volume of requests..."
}

Status Code Definitions

Code	Error Code	Description
200	SUCCESS	Recognition success
400	INVALID_REQUEST_FORMAT	Invalid payload or corrupted Base64 structure.
402	INSUFFICIENT_CREDITS	Account balance too low
413	FILE_TOO_LARGE	Decoded image exceeds 4.5MB
415	INVALID_CONTENT_TYPE	Not using application/json
422	CONTENT_POLICY_VIOLATION	AI safety/policy block
500	PROCESSING_ERROR	Downstream processing fault
503	SYSTEM_BUSY	API Rate limit reached