My first encounter with Base64 was when sending images to the ChatGPT API. You have to convert images to Base64 before passing them in. Back then I just used whatever tool others had built.
But while researching web monetization, I realized a lot of people actually use Base64 conversion tools. So I tried them out. The UI looked like it was from 2014. The bigger problem was Korean text. I encoded "안녕하세요" and it came back garbled. Decoding didn't work properly either.
Something this basic doesn't even work, yet it's ranking at the top? I figured I could just build my own.
The Korean Text Problem
JavaScript's btoa() and atob() don't handle Unicode properly by default. I asked Cursor AI about it, and it said to run the text through TextEncoder and TextDecoder for UTF-8 byte conversion. Fixed it quickly.
When I checked the top-ranking sites, most only handled English correctly and broke on Korean. I saw an opportunity there.
What I Built
The basics: encode text to Base64, decode Base64 back to text. Results appear in real time as you type.
Image files work too. Drag and drop an image and it automatically converts to a Base64 string. Large images can produce strings so long they cause performance issues, so I added a file size limit with a warning.
There's a copy button, obviously. Dragging to select a massive Base64 string is pure suffering.
Made it responsive for mobile use, and gave the design a modern look.
How's Monetization Going?
Honestly, I haven't even passed AdSense review yet. There's no real strategy — I'm just hoping to rank in search. A vague hope that if the user experience is good enough, traffic will come. If it does, great. If not, at least I use it myself.
Want to try it? Check out the Base64 Encoder/Decoder.