4lin.uk API Docs – Create Short Links Programmatically

Getting Started

4Lin.UK provides a simple JSON API for shortening URLs. No registration, no API keys, no complex authentication. Just send a request and get your short URL.

Base URL

https://4lin.uk/api.php

All endpoints use this base URL with the action parameter.

Quick Start (GET for testing)

For quick testing, you can shorten a URL using a simple GET request:

https://4lin.uk/api.php?action=shorten&url=https://example.com

For production use, POST JSON is recommended (see examples below).

Rate Limiting

Fair Use Policy

60 requests per minute per IP/session
No API keys - completely open
429 Too Many Requests response when exceeded

Rate Limit Headers (when available)

X-RateLimit-Limit: 60
X-RateLimit-Remaining: 58
X-RateLimit-Reset: 1623456789

API Endpoints

GET ?action=info

Get API information, version, and available endpoints.

Response

{
  "success": true,
  "service": "4Lin.UK URL Shortener",
  "version": "1.0",
  "rate_limit": "60 requests per minute",
  "endpoints": {
    "GET ?action=info": "API information",
    "GET ?action=stats": "Service statistics",
    "GET ?action=clicks&code={code}": "Get click count",
    "GET ?action=qr&code={code}": "Get QR code",
    "GET/POST ?action=shorten": "Create short URL"
  }
}

GET ?action=stats

Get global service statistics.

Response

{
  "success": true,
  "stats": {
    "total_urls_shortened": 12345,
    "total_clicks": 678901,
    "service_status": "operational",
    "rate_limit": "60/minute"
  }
}

POST ?action=shorten

Create a shortened URL. Returns existing short code if the URL already exists.
Tip: You can also use GET for quick testing (see Getting Started).

Request Parameters

Parameter	Type	Required	Description
`url`	string	Yes	The URL to shorten (http:// or https://)

Example Request (POST JSON)

POST /api.php?action=shorten HTTP/1.1
Host: 4lin.uk
Content-Type: application/json

{
  "url": "https://example.com/very/long/url"
}

Success Response

{
  "success": true,
  "short_code": "aB3xY7",
  "short_url": "https://4lin.uk/aB3xY7",
  "original_url": "https://example.com/very/long/url",
  "is_new": true
}

GET ?action=clicks&code={code}

Get the number of clicks for a specific short URL.

Parameter	Type	Required	Description
`code`	string	Yes	The short code (e.g., aB3xY7)

Response

{
  "success": true,
  "short_code": "aB3xY7",
  "short_url": "https://4lin.uk/aB3xY7",
  "clicks": 42
}

GET ?action=qr&code={code}

Get a QR code URL for a short link.

Parameter	Type	Required	Description
`code`	string	Yes	The short code (e.g., aB3xY7)
`size`	int	Optional	QR code size in pixels (default: 200)

Response

{
  "success": true,
  "short_code": "aB3xY7",
  "short_url": "https://4lin.uk/aB3xY7",
  "qr_code_url": "https://api.qrserver.com/v1/create-qr-code/?size=200x200&data=https%3A%2F%2F4lin.uk%2FaB3xY7",
  "qr_code_html": "<img src="https://api.qrserver.com/v1/create-qr-code/?size=200x200&data=https%3A%2F%2F4lin.uk%2FaB3xY7" alt="QR Code" width="200" height="200">"
}

Example QR Code for https://4lin.uk/aB3xY7

Code Examples

JavaScript

// Shorten a URL using fetch
async function shortenUrl(url) {
  const response = await fetch('https://4lin.uk/api.php?action=shorten', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ url })
  });

  const data = await response.json();

  if (data.success) {
    console.log('Short URL:', data.short_url);
    console.log('QR Code:', data.qr_code_url);
  }

  return data;
}

// Example usage
shortenUrl('https://example.com').then(console.log);

// Get click count
async function getClicks(shortCode) {
  const response = await fetch(`https://4lin.uk/api.php?action=clicks&code=${shortCode}`);
  const data = await response.json();
  return data.clicks;
}

// Get QR code URL
function getQRCode(shortCode, size = 200) {
  return `https://4lin.uk/api.php?action=qr&code=${shortCode}&size=${size}`;
}

Python

import requests

def shorten_url(url):
    response = requests.post(
        'https://4lin.uk/api.php?action=shorten',
        json={'url': url}
    )
    return response.json()

def get_clicks(short_code):
    response = requests.get(
        f'https://4lin.uk/api.php?action=clicks&code={short_code}'
    )
    data = response.json()
    return data.get('clicks', 0)

def get_qr_code(short_code, size=200):
    return f'https://4lin.uk/api.php?action=qr&code={short_code}&size={size}'

# Example usage
result = shorten_url('https://example.com')
print("Short URL:", result.get('short_url'))
print("QR Code:", result.get('qr_code_url'))

clicks = get_clicks(result.get('short_code', ''))
print("Clicks:", clicks)

PHP

<?php
function shortenUrl($url) {
    $ch = curl_init('https://4lin.uk/api.php?action=shorten');
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode(['url' => $url]));
    curl_setopt($ch, CURLOPT_HTTPHEADER, ['Content-Type: application/json']);

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

    return json_decode($response, true);
}

function getClicks($shortCode) {
    $response = file_get_contents("https://4lin.uk/api.php?action=clicks&code={$shortCode}");
    $data = json_decode($response, true);
    return $data['clicks'] ?? 0;
}

// Example usage
$result = shortenUrl('https://example.com');
echo "Short URL: " . ($result['short_url'] ?? '') . PHP_EOL;
echo "QR Code: " . ($result['qr_code_url'] ?? '') . PHP_EOL;
?>

cURL

# Shorten a URL (POST JSON)
curl -X POST "https://4lin.uk/api.php?action=shorten" \
  -H "Content-Type: application/json" \
  -d '{"url":"https://example.com"}'

# Shorten a URL (GET quick test)
curl "https://4lin.uk/api.php?action=shorten&url=https://example.com"

# Get click count
curl "https://4lin.uk/api.php?action=clicks&code=aB3xY7"

# Get QR code URL
curl "https://4lin.uk/api.php?action=qr&code=aB3xY7&size=200"

# Get API info
curl "https://4lin.uk/api.php?action=info"

# Get service stats
curl "https://4lin.uk/api.php?action=stats"

Response Formats

Success Response

Successful responses include "success": true.

{
  "success": true,
  "short_code": "aB3xY7",
  "short_url": "https://4lin.uk/aB3xY7",
  "original_url": "https://example.com",
  "is_new": true
}

Existing URL Response

If a URL has already been shortened, the API returns the existing short code.

{
  "success": true,
  "short_code": "aB3xY7",
  "short_url": "https://4lin.uk/aB3xY7",
  "original_url": "https://example.com",
  "is_new": false
}

Error Codes

Errors return an appropriate HTTP status code and a JSON body containing an error message. (Some errors may also include extra fields like message and retry_after.)

Status Code	Error	Description	Solution
`400`	Missing URL	No URL provided	Add the `url` parameter to the request
`400`	Invalid URL format	URL is malformed	Ensure it includes `http://` or `https://`
`404`	Short code not found	The short code doesn't exist	Check the short code and try again
`404`	Unknown action	Invalid API endpoint	Check the `action` parameter
`429`	Rate limit exceeded	Too many requests	Wait and retry after the value in `retry_after` (seconds)
`405`	Method not allowed	Wrong HTTP method	Use GET/POST as specified
`500`	Server error	Internal error	Try again later

Error Response Examples

400 Bad Request

{
  "error": "Invalid URL format"
}

429 Too Many Requests

{
  "error": "Rate limit exceeded",
  "message": "Maximum 60 requests per minute",
  "retry_after": 60
}

Frequently Asked Questions

❓ Do I need an API key?

No. The 4Lin.UK API is completely free and open. No registration, no keys, no authentication required.

❓ What are the rate limits?

60 requests per minute per IP/session to ensure fair usage for all developers.

❓ Are links permanent?

Links don’t expire by default. We may remove links that violate our Terms (malware/phishing/illegal content) or are abusive.

❓ Can I use custom short codes?

Currently, the API generates random short codes. Custom aliases are coming soon.

❓ What's the maximum URL length?

There’s no enforced limit, but URLs longer than 2000 characters may cause issues with some browsers.

❓ Is HTTPS required?

We recommend including the full URL with protocol. If your API auto-adds HTTPS when missing, document that behavior here.

❓ Can I use this commercially?

Yes. The API is free for personal and commercial use. No attribution required.

API Documentation

Getting Started

Base URL

Quick Start (GET for testing)

Rate Limiting

Fair Use Policy

Rate Limit Headers (when available)

API Endpoints

Response

Response

Request Parameters

Example Request (POST JSON)

Success Response

Response

Response

Code Examples

JavaScript

Python

PHP

cURL

Response Formats

Success Response

Existing URL Response

Error Codes

Error Response Examples

Frequently Asked Questions

❓ Do I need an API key?

❓ What are the rate limits?

❓ Are links permanent?

❓ Can I use custom short codes?

❓ What's the maximum URL length?

❓ Is HTTPS required?

❓ Can I use this commercially?