Base64 Encode/Decode

Base64 turns arbitrary binary data — an image, a PDF, a chunk of encrypted bytes — into a string made up only of the 64 characters A–Z, a–z, 0–9, +, and / (plus = for padding). It isn't encryption or compression; a Base64 string is roughly 33% larger than the data it represents, and anyone can decode it back instantly with no key required. The reason it exists is much more mundane: a lot of transport formats and storage systems — email (MIME attachments), JSON fields, URL query parameters, CSS/HTML `data:` URIs, config files — were built to carry plain text safely, and choke on raw binary bytes like line-feed characters or embedded nulls. Base64-encoding a binary payload turns it into a chunk of plain text that any of those systems can carry without corrupting it.

This tool runs the encoding and decoding with plain JavaScript directly in your browser — nothing you type or upload is sent to a server. Text is encoded using `TextEncoder`/`btoa` under the hood so multi-byte UTF-8 characters (emoji, accented letters, CJK text) round-trip correctly, not just plain ASCII. Files are read locally via the browser's `FileReader` API, which means a multi-megabyte image never leaves your machine just to find out what its Base64 form looks like.

The Text tab handles the everyday case: type or paste something, flip between Encode and Decode, and the output updates live. The URL-safe option swaps the `+`/`/` characters for `-`/`_` and drops the trailing `=` padding, which is what you need when a Base64 value has to sit inside a URL or a filename rather than a JSON field. The File tab goes further: drop in an image, PDF, or any other file to get back both the raw Base64 and a ready-to-use `data:` URI you can paste straight into an `<img src>` or a CSS `background-image` — handy for embedding a small icon without a separate HTTP request. Paste that data URI (or just a bare Base64 string plus a MIME type) back into the decode box and the tool reconstructs the original bytes, offering an image preview automatically and a one-click download.

A common point of confusion worth flagging directly: Base64 is an encoding, not a security measure. A Base64 string is trivially reversible by design, so it should never be used as a substitute for real encryption — if you're looking to protect a token or a secret, encode it for transport with this tool by all means, but don't mistake that for hiding it. For inspecting the structure of an already-decoded JSON payload, the JSON Formatter & Validator tool is a natural next stop.