Image CaptionImage Caption API

OnlineCredit Usage:10 per callRefreshed 1 month ago
avg: 1847ms|p50: 1681ms|p75: 1958ms|p90: 2290ms|p99: 2955ms

Image Caption is an AI-powered tool that generates descriptive captions for images. Simply upload an image and receive a natural language description of its contents.

The Image Caption API provides reliable and fast access to image caption data through a simple REST interface. Built for developers who need consistent, high-quality results with minimal setup time.

To use Image Caption, you need an API key. You can get one by creating a free account and visiting your dashboard.

POST Endpoint

URL
https://api.apiverve.com/v1/imagecaption

Code Examples

Here are examples of how to call the Image Caption API in different programming languages:

cURL Request
curl -X POST \
  "https://api.apiverve.com/v1/imagecaption" \
  -H "X-API-Key: your_api_key_here" \
  -F "image=@/path/to/image.jpg"
JavaScript (Fetch API)
const formData = new FormData();
formData.append('image', fileInput.files[0]);

const response = await fetch('https://api.apiverve.com/v1/imagecaption', {
  method: 'POST',
  headers: {
    'X-API-Key': 'your_api_key_here'
  },
  body: formData
});

const data = await response.json();
console.log(data);
Python (Requests)
import requests

headers = {
    'X-API-Key': 'your_api_key_here'
}

files = {
    'image': open('/path/to/image.jpg', 'rb')
}

response = requests.post('https://api.apiverve.com/v1/imagecaption', headers=headers, files=files)

data = response.json()
print(data)
Node.js (Native HTTPS)
const fs = require('fs');
const FormData = require('form-data');

const form = new FormData();
form.append('image', fs.createReadStream('/path/to/image.jpg'));

fetch('https://api.apiverve.com/v1/imagecaption', {
  method: 'POST',
  headers: {
    'X-API-Key': 'your_api_key_here',
    ...form.getHeaders()
  },
  body: form
})
.then(res => res.json())
.then(data => console.log(data));
PHP (cURL)
<?php

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, 'https://api.apiverve.com/v1/imagecaption');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'X-API-Key: your_api_key_here'
]);

$postFields = [
    'image' => new CURLFile('/path/to/image.jpg')
];

curl_setopt($ch, CURLOPT_POSTFIELDS, $postFields);

$response = curl_exec($ch);
curl_close($ch);

$data = json_decode($response, true);
print_r($data);

?>
Go (net/http)
package main

import (
    "bytes"
    "fmt"
    "io"
    "mime/multipart"
    "net/http"
    "os"
)

func main() {
    file, _ := os.Open("/path/to/image.jpg")
    defer file.Close()

    body := &bytes.Buffer{}
    writer := multipart.NewWriter(body)
    part, _ := writer.CreateFormFile("image", "image.jpg")
    io.Copy(part, file)
    writer.Close()

    req, _ := http.NewRequest("POST", "https://api.apiverve.com/v1/imagecaption", body)
    req.Header.Set("X-API-Key", "your_api_key_here")
    req.Header.Set("Content-Type", writer.FormDataContentType())

    client := &http.Client{}
    resp, err := client.Do(req)
    if err != nil {
        panic(err)
    }
    defer resp.Body.Close()

    respBody, _ := io.ReadAll(resp.Body)
    fmt.Println(string(respBody))
}
Ruby (Net::HTTP)
require 'net/http'
require 'uri'
require 'json'

uri = URI('https://api.apiverve.com/v1/imagecaption')
http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = true

request = Net::HTTP::Post::Multipart.new(
  uri.path,
  'image' => UploadIO.new(File.open('/path/to/image.jpg'), 'image/jpeg', 'image.jpg')
)

request['X-API-Key'] = 'your_api_key_here'

response = http.request(request)
puts JSON.pretty_generate(JSON.parse(response.body))
C# (HttpClient)
using System;
using System.IO;
using System.Net.Http;
using System.Threading.Tasks;

class Program
{
    static async Task Main(string[] args)
    {
        using var client = new HttpClient();
        client.DefaultRequestHeaders.Add("X-API-Key", "your_api_key_here");

        using var content = new MultipartFormDataContent();
        using var fileStream = File.OpenRead("/path/to/image.jpg");
        content.Add(new StreamContent(fileStream), "image", "image.jpg");

        var response = await client.PostAsync("https://api.apiverve.com/v1/imagecaption", content);
        response.EnsureSuccessStatusCode();

        var responseBody = await response.Content.ReadAsStringAsync();
        Console.WriteLine(responseBody);
    }
}

Authentication

The Image Caption API requires authentication via API key. Include your API key in the request header:

Required Header
X-API-Key: your_api_key_here

Learn more about authentication →

Interactive API Playground

Test the Image Caption API directly in your browser with live requests and responses.

File Upload Required

The Image Caption API requires file upload via multipart/form-data. Do not use Content-Type: application/json for Image Caption.
PropertyValue
Field Nameimage
Accepted Types.jpg, .jpeg, .png, .gif
Max File Size5MB
File Upload Example (cURL)
curl -X POST "https://api.apiverve.com/v1/imagecaption" \
  -H "X-API-Key: your_api_key_here" \
  -F "image=@/path/to/your/file"
File Upload Example (JavaScript)
const formData = new FormData();
formData.append('image', fileInput.files[0]);

const response = await fetch('https://api.apiverve.com/v1/imagecaption', {
  method: 'POST',
  headers: {
    'X-API-Key': 'your_api_key_here'
  },
  body: formData
});

const data = await response.json();
console.log(data);

Parameters

The following parameters are available for the Image Caption API:

Caption Image

ParameterTypeRequiredDescriptionDefaultExample
imagestringrequired
Upload an image file to generate a caption (supported formats: JPG, PNG, GIF, max 5MB)
-https://upload.wikimedia.org/wikipedia/commons/thumb/3/3a/Cat03.jpg/640px-Cat03.jpg

Response

The Image Caption API returns responses in JSON, XML, YAML, and CSV formats:

Example Responses

JSON Response
200 OK
{
  "status": "ok",
  "error": null,
  "data": {
    "caption": "A golden retriever running through a grassy field on a sunny day"
  }
}
XML Response
200 OK
<?xml version="1.0" encoding="UTF-8"?>
<response>
  <status>ok</status>
  <error xsi:nil="true" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"/>
  <data>
    <caption>A golden retriever running through a grassy field on a sunny day</caption>
  </data>
</response>
YAML Response
200 OK
status: ok
error: null
data:
  caption: A golden retriever running through a grassy field on a sunny day
CSV Response
200 OK
keyvalue
captionA golden retriever running through a grassy field on a sunny day

Response Structure

All API responses follow a consistent structure with the following fields:

FieldTypeDescriptionExample
statusstringIndicates whether the request was successful ("ok") or failed ("error")ok
errorstring | nullContains error message if status is "error", otherwise nullnull
dataobject | nullContains the API response data if successful, otherwise null{...}

Learn more about response formats →

Response Data Fields

When the request is successful, the data object contains the following fields:

FieldTypeSample ValueDescription
captionstring"A golden retriever running through a grassy field on a sunny day"AI-generated natural language description of image contents

Headers

Required and optional headers for Image Caption API requests:

Header NameRequiredExample ValueDescription
X-API-Keyrequiredyour_api_key_hereYour APIVerve API key. Found in your dashboard under API Keys.
Acceptoptionalapplication/jsonSpecify response format: application/json (default), application/xml, or application/yaml
User-AgentoptionalMyApp/1.0Identifies your application for analytics and debugging purposes
X-Request-IDoptionalreq_123456789Custom request identifier for tracking and debugging requests
Cache-Controloptionalno-cacheControl caching behavior for the request and response

Learn more about request headers →

CORS Support

The Image Caption API supports Cross-Origin Resource Sharing (CORS) with wildcard configuration, allowing you to call Image Caption directly from browser-based applications without proxy servers.

CORS HeaderValueDescription
Access-Control-Allow-Origin*Accepts requests from any origin
Access-Control-Allow-Methods*Accepts any HTTP method
Access-Control-Allow-Headers*Accepts any request headers

Browser Usage: You can call Image Caption directly from JavaScript running in the browser without encountering CORS errors. No proxy server or additional configuration needed.

Learn more about CORS support →

Rate Limiting

Image Caption API requests are subject to rate limiting based on your subscription plan. These limits ensure fair usage and maintain service quality for all Image Caption users.

PlanRate LimitDescription
Free5 requests/minHard rate limit enforced - exceeding will return 429 errors
StarterNo LimitProduction ready - standard traffic priority
ProNo LimitProduction ready - preferred traffic priority
MegaNo LimitProduction ready - highest traffic priority

Learn more about rate limiting →

Rate Limit Headers

When rate limits apply, each Image Caption response includes headers to help you track your usage:

HeaderDescription
X-RateLimit-LimitMaximum number of requests allowed per time window
X-RateLimit-RemainingNumber of requests remaining in the current window
X-RateLimit-ResetUnix timestamp when the rate limit window resets

Handling Rate Limits

Free Plan: When you exceed your rate limit, Image Caption returns a 429 Too Many Requests status code. Your application should implement appropriate backoff logic to handle this gracefully.

Paid Plans: No rate limiting or throttling applied. All paid plans (Starter, Pro, Mega) are production-ready.

Best Practices for Image Caption:

  • Monitor the rate limit headers to track your Image Caption usage (Free plan only)
  • Cache image caption responses where appropriate to reduce API calls
  • Upgrade to Pro or Mega for guaranteed no-throttle Image Caption performance

Note: Image Caption rate limits are separate from credit consumption. You may have credits remaining but still hit rate limits when using Image Caption on Free tier.

Error Codes

The Image Caption API uses standard HTTP status codes to indicate success or failure:

CodeMessageDescriptionSolution
200OKRequest successful, data returnedNo action needed - request was successful
400Bad RequestInvalid request parameters or malformed requestCheck required parameters and ensure values match expected formats
401UnauthorizedMissing or invalid API keyInclude x-api-key header with valid API key from dashboard
403ForbiddenAPI key lacks permission or insufficient creditsCheck credit balance in dashboard or upgrade plan
429Too Many RequestsRate limit exceeded (Free: 5 req/min)Implement request throttling or upgrade to paid plan
500Internal Server ErrorServer error occurredRetry request after a few seconds, contact support if persists
503Service UnavailableAPI temporarily unavailableWait and retry, check status page for maintenance updates

Learn more about error handling →

Need help? Contact support with your X-Request-ID for assistance.

Integrate Image Caption with SDKs

Get started quickly with official Image Caption SDKs for your preferred language. Each library handles authentication, request formatting, and error handling automatically.

Available for Node.js, Python, C#/.NET, and Android/Java. All SDKs are open source and regularly updated.

Integrate Image Caption with No-Code API Tools

Connect the Image Caption API to your favorite automation platform without writing code. Build workflows that leverage image caption data across thousands of apps.

All platforms use your same API key to access Image Caption. Visit our integrations hub for step-by-step setup guides.

Frequently Asked Questions

How do I get an API key for Image Caption?
Sign up for a free account at dashboard.apiverve.com. Your API key will be automatically generated and available in your dashboard. The same key works for Image Caption and all other APIVerve APIs. The free plan includes 1,000 credits plus a 500 credit bonus.
How many credits does Image Caption cost?

Each successful Image Caption API call consumes credits based on plan tier. Check the pricing section above for the exact credit cost. Failed requests and errors don't consume credits, so you only pay for successful image caption lookups.

Can I use Image Caption in production?

The free plan is for testing and development only. For production use of Image Caption, upgrade to a paid plan (Starter, Pro, or Mega) which includes commercial use rights, no attribution requirements, and guaranteed uptime SLAs. All paid plans are production-ready.

Can I use Image Caption from a browser?
Yes! The Image Caption API supports CORS with wildcard configuration, so you can call it directly from browser-based JavaScript without needing a proxy server. See the CORS section above for details.
What happens if I exceed my Image Caption credit limit?

When you reach your monthly credit limit, Image Caption API requests will return an error until you upgrade your plan or wait for the next billing cycle. You'll receive notifications at 80% and 95% usage to give you time to upgrade if needed.

What's Next?

Continue your journey with these recommended resources

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