Build an Image Watermarking Web App with Python

Level: Real World

Previously we built a project that let the user create a watermarked image out of a main image and a logo image. You can find the source code of that previous project here.

Today we will extend that project by creating a web-based image watermarking application using Streamlit that allows users to upload images, add watermarks, and download the results directly from their browser.

Project Task

Create a Streamlit image watermarking app that:

• Uses Streamlit to create an interactive web interface

• Provides file uploaders for the main image and watermark logo

• Displays uploaded images in real-time as previews

• Positions the watermark in the bottom-right corner of the image

• Shows the watermarked result instantly in the browser

• Includes a download button to save the watermarked image

• Uses Pillow (PIL) for image processing

• Features a clean, two-column layout for easy use

This project gives you hands-on practice with Streamlit web apps, image processing, file uploads, and creating interactive user interfaces — essential skills for building modern web-based Python applications.

Expected Output

Here is how the app works. The user uploads a main image and a logo image to the web app. Then the user presses the “Add Watermark” button and the watermarked image is displayed with a button to download the image.

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Skeleton and Solution

Below you will find both a downloadable skeleton.py file to help you code the project with comment guides and the downloadable solution.py file containing the correct solution.

Get the code skeleton here: