---
title: "Base64 encoder & decoder"
canonical: "https://devtools.nicxon.tech/tools/base64/"
source: "https://devtools.nicxon.tech/tools/base64/"
generator: devtools.nicxon.tech
---

# Base64 encoder & decoder

> Encode UTF-8 text or any file to Base64 (standard or URL-safe), and decode a Base64 string back to text or a downloadable file. Runs in your browser; no upload.

## What this does

Base64 maps arbitrary bytes onto 64 printable ASCII characters so binary
 data can pass through systems that only handle text. This tool encodes
 UTF-8 text or any file you select, and decodes a Base64 string back to
 text — or, when the bytes aren't valid text, to a downloadable file. It
 supports both the standard alphabet and the URL-safe variant, and it
 tolerates missing padding and embedded whitespace on decode.

File encoding happens with the `File` and `FileReader`
 APIs in your browser. The bytes are never uploaded, so encoding a
 certificate, a private key, or a document to embed in a config file is
 safe to do here.

## When you'd use it

- Embedding a small image or font in a CSS `data:` URI or an HTML page.
- Putting a binary file into a JSON or YAML field that only accepts strings.
- Decoding the `Authorization: Basic` header value to see the username and password it carries.
- Inspecting the payload of a Base64URL token by hand.
- Preparing a Kubernetes `Secret`, whose values are Base64-encoded.

## Worked example

Encode the text `user:pa55` with the standard alphabet:

```
dXNlcjpwYTU1
```

That is exactly what sits after `Basic ` in an HTTP
 `Authorization` header. Switch Mode to Decode, paste
 `dXNlcjpwYTU1`, and you get `user:pa55` back —
 demonstrating that Basic auth offers no confidentiality without HTTPS.

Now tick *URL-safe* and encode the bytes `0xFB 0xFF`
 (paste them as text won't work; use a 2-byte file). Standard Base64 gives
 `+/8=`; URL-safe gives `-_8` — same bytes, different
 characters, no padding.

## Limits and gotchas

- **Not a cipher.** Base64 provides zero secrecy. Encode-then-encrypt, never encode-instead-of-encrypt.
- **Text mode assumes UTF-8.** Pasting text in another encoding and encoding it will produce UTF-8 bytes, which may not match what another system expects.
- **Whitespace on decode is ignored,** which is lenient. A stricter decoder elsewhere may reject the same input if it contains newlines.
- **Large files** are held entirely in memory as a string during encoding; multi-hundred-megabyte files can exhaust the tab.
- **MIME line wrapping** (76-character lines) is not added. If a legacy system needs wrapped output, wrap it after copying.

## How to use

- **Pick encode or decode** — Set Mode to Encode to produce Base64, or Decode to read Base64 back.
- **Provide input** — Type or paste text into the box, or choose a file to encode. Files are read locally.
- **Choose the alphabet** — Leave standard Base64 for most uses, or tick URL-safe for tokens that travel in a URL or filename.
- **Read the output** — Copy the encoded string, or for a decoded binary result use the download button.

## Frequently asked questions

### What is the difference between Base64 and Base64URL?

Standard Base64 uses +, /, and = padding. Those three characters have special meaning in URLs and filenames, so Base64URL replaces + with -, / with _, and usually drops the = padding. The decoded bytes are identical; only the text representation differs. JWTs use Base64URL.

### Why did decoding produce garbled characters?

The Base64 decoded fine, but the resulting bytes are not UTF-8 text — they might be an image, a gzip stream, or text in another encoding. This tool detects that and offers a download instead. Garbled output specifically means the bytes were forced through a UTF-8 decoder that couldn’t make sense of them.

### Is Base64 encryption? Is it safe to put a password in it?

No. Base64 is a reversible encoding with no key. Anyone can decode it instantly. It exists to carry binary data through text-only channels (email, JSON, URLs), not to protect anything. Never treat a Base64 string as a secret in itself.

### The encoded output is bigger than my input — is that expected?

Yes. Base64 represents every 3 bytes as 4 ASCII characters, so output is about 33% larger than input, plus padding and any line breaks. This is the cost of using only printable characters.

---
*Source: [https://devtools.nicxon.tech/tools/base64/](https://devtools.nicxon.tech/tools/base64/) — generated by devtools.nicxon.tech.*