I built a Base64 encoder that doesn't phone home

I've been meaning to build a proper Base64 tool for ages. Every time I need to quickly encode or decode something, I'm stuck either writing a tiny script or using some sketchy site that might be logging my data.

So I built one: Base64 Encoder/Decoder

What it does

• Encode any text to Base64 instantly
• Decode Base64 back to plain text
• URL-safe mode (replaces + with - and / with _)
• One-click copy to clipboard
• 100% client-side — nothing ever leaves your browser

Why I care about the "no server" part

A lot of online Base64 tools send your input to a backend. For most use cases that's fine — but if you're dealing with tokens, API keys, or anything vaguely sensitive, you probably don't want that.

This tool runs entirely in your browser. There's no server receiving your input. The code is vanilla JS, no frameworks, no build step — you can literally read the source by pressing Ctrl+U.

The URL-safe variant

Standard Base64 uses + and / which break when you put them in URLs or filenames. URL-safe Base64 replaces those with - and _. I see devs forget this all the time and then spend 10 minutes debugging a 400 error. The tool has a toggle so you can switch between standard and URL-safe instantly.

Mobile works too

I made it mobile-first. The textarea is big enough to actually type in on a phone, and the copy button works properly on iOS (which has historically been annoying to get right).

Try it: billion-base64.pages.dev

Let me know if there are other encodings you'd want — thinking about adding hex and binary next.