---
title: "Base64 encoder and decoder — free, runs in your browser"
description: "Encode text to Base64 or decode it back, entirely in your browser. Free, no sign-up, and nothing you enter leaves your browser."
url: https://atoneplace.net/tools/base64-encoder/
site: "At One Place"
---

# Base64 encoder and decoder

Encode text to Base64 or decode it back, entirely in your browser.

## How it works

Base64 represents binary data using 64 printable ASCII characters, so it can travel through systems that only handle text — email attachments, data URIs, JSON payloads, HTTP headers.

It works by taking three bytes at a time (24 bits) and re-splitting them into four 6-bit groups, each mapped to a character from A–Z, a–z, 0–9, + and /. Because three bytes become four characters, Base64 data is always about 33% larger than the original. When the input length is not a multiple of three, the output is padded with one or two = signs.

Base64 is an encoding, not encryption. It provides no security whatsoever — anyone can decode it instantly, as this page demonstrates. Encoding a password or key in Base64 hides it from casual reading and from nothing else.

> This tool runs entirely in your browser. Nothing you enter is sent to a server, logged or stored, and the page keeps working with the network disconnected.

## Common questions

### Is Base64 encryption?

No. It is a reversible encoding with no key and no secret. Anyone can decode it, so it provides no security at all.

### Why does Base64 make files bigger?

Every three bytes of input become four characters of output, so the result is roughly 33% larger, plus padding.

### What do the equals signs at the end mean?

Padding. Base64 works in three-byte blocks, so when the input does not divide evenly, one or two = characters mark how many bytes were missing from the final block.

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