What is the size overhead of Base64 encoding?

Base64 increases data size by approximately 33% because every 3 bytes become 4 ASCII characters.

What is URL-safe Base64?

URL-safe Base64 replaces + with - and / with _ so the output is safe to use in URLs without percent-encoding.

Can I encode binary files like images?

Yes. Use the file upload option. The tool reads raw bytes via FileReader and encodes them correctly.

Is Base64 a form of encryption?

No. Base64 is reversible encoding with no key or secret. It provides no security on its own.

How do I Base64 encode from the command line?

On Linux or macOS run echo -n 'Hello, World!' | base64, which prints SGVsbG8sIFdvcmxkIQ==. Leave out -n and the trailing newline gets encoded too, giving a different string. In PowerShell use [Convert]::ToBase64String([Text.Encoding]::UTF8.GetBytes('Hello, World!')).

Why does the URL-safe output still end in =?

The URL-safe option swaps + for - and / for _ but keeps the = padding. Base64URL in JWTs and many APIs leaves the padding out, so delete the trailing = signs if the system you are sending to expects unpadded Base64URL.

Base64 Encoder

Paste text or upload a file and get the Base64-encoded string instantly.

Paste text and click Encode to get its Base64 string: Hello, World! becomes SGVsbG8sIFdvcmxkIQ==.

Input

Text to encode

Or upload file:

Alphabet:

Standard URL-safe

Base64 Output

Quick answer

Paste text and click Encode to get its Base64 string: Hello, World! becomes SGVsbG8sIFdvcmxkIQ==. Every 3 bytes turn into 4 characters, so the output is about a third longer, padded with = at the end. Pick a file instead to encode an image or any other file.

Examples

Input	Base64 output
Hello, World!	SGVsbG8sIFdvcmxkIQ==
Hi	SGk=
user:pass	dXNlcjpwYXNz
café	Y2Fmw6k=
<<???>>	PDw/Pz8+Pg==
<<???>> (URL-safe)	PDw_Pz8-Pg==

Paste your text, then click Encode.

Summary

Paste text or upload a file and get the Base64-encoded string instantly.

How it works

Paste text into the input area or click "Choose file" to upload a binary file.
Select Standard or URL-safe alphabet as needed.
Click Encode to convert the text. A file is encoded as soon as you pick it, so choose the alphabet first.
Copy the Base64 output with the Copy button.

Use cases

Embedding images as data URIs in CSS
Encoding credentials for HTTP Basic Auth headers
Passing binary data in JSON API payloads

Frequently Asked Questions

Last updated: 2026-05-29 · Reviewed by Nham Vu