How I "Vibe-Coded" a Privacy-First, Client-Side Base64 Tool (Deep-Dive into Unicode Handling in JS)

Hey DEV community! 👋

As developers, we handle Base64 encoding and decoding almost daily—whether we're debugging API payloads, formatting authorization headers, or embedding small graphic assets directly into stylesheets.

However, many online translation utilities process your inputs on their backend servers. If you are dealing with sensitive configuration parameters, internal logs, or keys, pasting that data into a third-party web tool is a clear data privacy risk.

To solve this, I decided to "vibe-code" a lightweight, strictly browser-based, privacy-oriented Base64 Encoder & Decoder.

In this post, we will look at how this utility was built using AI assistance and vanilla JavaScript, along with the core logic to handle common encoding pitfalls.