---
title: "Creating a Polyglot File: How to Hide a ZIP Archive Inside a PNG"
date: 2026-02-28
author: "xcropimage.io Team"
tags: ["tech", "file formats", "png", "zip", "polyglot files", "windows", "linux", "macos"]
lang: "en"
description: "Learn how to create a polyglot file by hiding a ZIP archive inside a PNG image across Windows, macOS, and Linux."
---

## Introduction

A polyglot file is a file that is valid in more than one format at the same time.

In this guide, you'll learn how to hide a ZIP archive (containing a video or any file) inside a PNG image. The resulting file will:

* Open normally as an image
* Be detected as an archive by tools like WinRAR
* Contain extractable hidden files

This works because PNG allows trailing data, and ZIP archives can be detected by signature scanning.

---

## How It Works

### PNG Flexibility

PNG viewers read only the image portion and ignore extra data appended at the end of the file.

### ZIP Detection

ZIP files contain a `PK` signature. Archive tools scan the entire file and detect this signature even if it appears after PNG data.

When you append a ZIP archive to a PNG, the result becomes a **polyglot file**.

---

## Step 1: Prepare Files

You need:

* `image.png`
* `video.mp4` (or any file)

Create the ZIP archive first:

### Windows / macOS / Linux


zip video.zip video.mp4


If you're on Windows without `zip`, right-click → Send to → Compressed (zipped) folder.

---

## Step 2: Merge PNG and ZIP

### 🪟 Windows (CMD)


copy /b image.png + video.zip output.png


---

### 🪟 Windows (PowerShell)


Get-Content image.png -Encoding Byte | Set-Content output.png -Encoding Byte
Get-Content video.zip -Encoding Byte | Add-Content output.png -Encoding Byte


---

### 🍎 macOS


cat image.png video.zip > output.png


---

### 🐧 Linux


cat image.png video.zip > output.png


---

## What Happens Next?

* `output.png` opens normally in image viewers.
* WinRAR or similar archive tools detect a ZIP archive inside it.
* You can extract the hidden video from the archive.

---

## Security Warning

Polyglot files can also be used maliciously.

Always:

* Avoid opening unknown archives
* Scan extracted files
* Be cautious with files from untrusted sources

---

## Conclusion

By appending a ZIP archive to a PNG file using system-native terminal commands, you can create a dual-format polyglot file.

This demonstrates how flexible file formats can be — and why understanding them is important for developers and security researchers.