Getting Started

Everything you need to integrate NPR API into your application.

NPR API provides a simple REST API for number plate recognition. Upload an image containing a vehicle and receive structured data including the detected plate number, confidence score, and vehicle details.

Quick Start

1. Create an account and navigate to Settings → API Keys
2. Generate a new API key
3. Make your first recognition request using the key

curl -X POST https://nprapi.com/api/v1/recognise \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -F "upload=@plate.jpg"

Authentication

All API requests require authentication via an API key. Include your key in the Authorization header as a Bearer token.

Authorization: Bearer your-api-key-here

Managing API Keys

You can create and revoke API keys from your dashboard under Settings → API Keys. Each key can be given a descriptive name to help you identify its purpose.

Making Requests

The API accepts multipart/form-data requests with an image file. Supported image formats are JPEG, PNG, and WebP.

Base URL

https://nprapi.com/api/v1

Request Headers

Image Requirements

• Maximum file size: 10MB
• Supported formats: JPEG, PNG, WebP
• Minimum resolution: 320 × 240 pixels

Recognition API

The recognition endpoint processes an image and returns detected number plates along with confidence scores and bounding box coordinates.

POST /api/v1/recognise

Submit an image for number plate recognition.

Request Parameters

Response

{
  "success": true,
  "results": [
    {
      "plate": "AB12 CDE",
      "confidence": 0.97,
      "region": "gb",
      "bounding_box": {
        "x": 120,
        "y": 340,
        "width": 200,
        "height": 60
      },
      "vehicle": {
        "make": "BMW",
        "colour": "Black",
        "year": 2021
      }
    }
  ]
}

Batch Processing

For processing multiple images at once, use the batch endpoint. Upload several images in a single request and receive results for all of them.

POST /api/v1/batch

Submit multiple images for recognition in a single request.

curl -X POST https://nprapi.com/api/v1/batch \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -F "images[]=@plate1.jpg" \
  -F "images[]=@plate2.jpg" \
  -F "images[]=@plate3.jpg"

Response

The batch response returns an array of results, one per image submitted. Each entry follows the same format as the single recognition response.

Vehicles

When a plate is recognised, the API automatically looks up associated vehicle data where available. This includes the vehicle make, colour, year, and more.

Vehicle Object

Error Handling

The API uses standard HTTP status codes to indicate success or failure. All error responses include a JSON body with details.

{
  "success": false,
  "error": {
    "code": "INVALID_IMAGE",
    "message": "The uploaded file is not a valid image."
  }
}

Status Codes

Error Codes

Rate Limits

API requests are rate-limited based on your plan. Rate limit information is included in the response headers of every request.

Response Headers

When you exceed the rate limit, the API responds with a 429 status code. Wait until the reset timestamp before retrying.