Image Compression API: Compress JPGs in Postman for Faster, SEO-Friendly Delivery

Large images can quietly slow down your website, increase storage costs, and affect Core Web Vitals — especially Largest Contentful Paint (LCP).

An image compression API helps solve this automatically by reducing image size during uploads, CMS imports, or workflow automation instead of manually optimizing files one by one.

In this guide, you’ll learn how to test the PDF4me **Compress Image API** in Postman and reduce JPG sizes in just a few steps.

Why Use an Image Compression API?

Teams commonly use image compression APIs to:

• Improve page load speed
• Reduce bandwidth and storage usage
• Deliver lighter images on mobile
• Improve SEO and user experience
• Automate image optimization workflows

Smaller images load faster, especially for hero banners and product visuals where performance matters most.

What You’ll Need Before Starting

Before sending your first request, keep these ready:

• A valid PDF4me API key
• A JPG or PNG image
• Postman installed
• Your image converted to Base64 format

Important: Remove the data:image/jpeg;base64, prefix before adding the Base64 string to the request body.

Step 1: Prepare Your Input File

Start with a reasonably large image so the compression difference is visible.

In the reference example from the original walkthrough, the source image was approximately 4.5 MB.

Step 2: Configure the Postman Request

Use the following API endpoint:

POST https://api.pdf4me.com/api/v2/CompressImage

Add these headers:

Header Value Content-Type application/json Authorization Your PDF4me API Key

Step 3: Add the JSON Request Body

In Postman, select:

Body → raw → JSON

Then paste the following:

{
  "docContent": "PASTE_BASE64_HERE",
  "docName": "output.jpg",
  "imageType": "JPG",
  "compressionLevel": "Max",
  "async": false
}

Understanding the Parameters

ParameterPurposedocContentBase64 version of the imagedocNameOutput file nameimageTypeJPG or PNGcompressionLevelMax, Medium, or LowasyncSet true for large files

Step 4: Send the Request

Click Send in Postman.

If successful, you’ll receive:

200 OK

Depending on your Postman view, the response may appear as:

• Base64 output

• Raw binary data

If Base64 is shown, decode it into a .jpg file. If binary appears, simply save the response as output.jpg.

Step 5: Compare File Sizes

After saving the compressed image, compare it with the original file.

In the sample run:

• Original image: ~4.5 MB
• Compressed image: ~2.6 MB

Actual compression results will vary depending on:

• image dimensions
• image quality
• selected compression level

If Max compression affects quality too much, try:

• Medium
• Low

Quick Troubleshooting

401 or Authorization Errors

Double-check:

• API key validity
• Authorization header formatting

Slow Requests or Timeouts

Try:

"async": true

You can also resize oversized images before compression.

Corrupt or Empty Output

Make sure:

• the Base64 string has no line breaks
• the data:image/...;base64, prefix is removed
• the source image opens correctly locally

Final Thoughts

Image compression APIs are one of the easiest ways to improve delivery performance across websites and applications. Instead of optimizing files manually, you can automate the process directly in your upload or processing pipeline.

Start with Postman, validate the request structure, and later move the same setup into production workflows or automation tools.

API Endpoint Used:

https://api.pdf4me.com/api/v2/CompressImage