Use CLI tools jdvin & jdvout with a JPG image, to embed or extract any file, up to 2GB (cover image + data file).

Compatible hosting sites, listed below, have their own much smaller image size limits:

• Flickr (200MB), ImgPile (100MB), ImgBB (32MB), PostImage (32MB), Reddit (20MB / -r option),
• Limit measured by data file size: Mastodon (~6MB), Tumblr (~64KB), Twitter (~10KB).

There are many other image hosting sites on the web that may also be compatible.

jdvrif partly derives from the technique demonstrated by security researcher David Buchanan.

Image credit: @DontSmileAI / PIN: 3495979549

Your embedded file is compressed (depending on file type) and encrypted with PIN protection.
The data file, if required, is split into multiple 64KB ICC Profile segments within the JPG cover image.

user1@linuxbox:~/Downloads/jdvrif-main/src/jdvin$ g++ main.cpp -O2 -lz -s -o jdvin
user1@linuxbox:~/Downloads/jdvrif-main/src/jdvin$ sudo cp jdvin /usr/bin

user1@linuxbox:~/Desktop$ jdvin 

Usage: jdvin [-r] <cover_image> <data_file>  
       jdvin --info

user1@linuxbox:~/Desktop$ jdvin Cover_Image.jpg Hidden_File.zip
  
Saved "file-embedded" JPG image: jrif_12462.jpg (143029 bytes).

Recovery PIN: [***2166776980***]

Important: Please remember to keep your PIN safe, so that you can extract the hidden file.

Complete!

user1@linuxbox:~/Downloads/jdvrif-main/src/jdvout$ g++ main.cpp -O2 -lz -s -o jdvout
user1@linuxbox:~/Downloads/jdvrif-main/src/jdvout$ sudo cp jdvout /usr/bin

user1@linuxbox:~/Desktop$ jdvout

Usage: jdvout <file_embedded_image>
       jdvout --info
        
user1@linuxbox:~/Desktop$ jdvout jrif_12462.jpg

PIN: **********

Extracted hidden file: Hidden_File.zip (6165 bytes).

Complete! Please check your file.

To correctly download images from X/Twitter or Reddit, click the image in the post to fully expand it, before saving.

To create "file-embedded" JPG images compatible for posting on Reddit, use the -r option with jdvin.
From the Reddit site, click "Create Post" then select "Images & Video" tab, to post your JPG image.

To correctly download an image from Flickr, click the download arrow near the bottom right-hand corner of the page and select Original for the size of image to download.

With X/Twitter & Tumblr, the small size limits (~10KB / ~64KB) are measured by the data file size and not the combined image size. As the data file is compressed when embedded, you should be able to hide files larger than 10KB or 64KB. For example, a 50KB workflow.json file compressed down to 6KB, making it compatible with sharing on X/Twitter.

Also with Mastodon, the size limit is measured by the data file size and not the combined image size.
For example, if your cover image is 1MB you can still embed a data file up to the ~6MB size limit.

You can try jdvrif from this site if you don't want to download and compile the source code.

Note: While the Web App will compress & encrypt the hidden file, it's less secure than the command-line version as it does not currently support PIN protection. Images created by the jdvrif command-line program with PIN protection are not currently compatible with the Web App version.

• ImgPile - You must sign in to an account before sharing your data-embedded JPG image on ImgPile.
  Sharing your image without logging in, your embedded data will not be preserved.

My other programs you may find useful:-

• pdvzip: CLI tool to embed a ZIP file within a tweetable and "executable" PNG-ZIP polyglot image.
• imgprmt: CLI tool to embed an image prompt (e.g. "Midjourney") within a tweetable JPG-HTML polyglot image.
• pdvrdt: CLI tool to encrypt, compress & embed any file type within a PNG image.
• pdvps: PowerShell / C++ CLI tool to encrypt & embed any file type within a tweetable and "executable" PNG image