What Is Base64? How to Encode and Decode Text & Images (Free Tool)

What Is Base64?

Base64 is an encoding that converts binary data (images, files, PDFs) into a plain-text format made of letters, numbers, and a few symbols: A–Z, a–z, 0–9, plus + and /. It exists because most network protocols and file formats (email, JSON, URLs) only safely carry text.

The name comes from the 64 characters in its alphabet. Every 3 bytes of binary data become 4 Base64 characters, and padding = is added when data does not divide evenly by three.

Why Developers Use Base64

• Email attachments — old email servers only carried 7-bit text, so attachments were Base64-encoded (this is what MIME does).
• Embedding images in HTML/CSS — a small image can be inlined as a data URI instead of a separate file:
• JSON payloads — binary data inside JSON must be text, so files are Base64-encoded before being sent.
• JWT tokens — the header and payload of a JWT are Base64-encoded JSON.

Encode and Decode in Two Steps

1. Paste your text, or drop a file, into the Base64 Encoder.
2. Click encode — you get a Base64 string you can paste into email, JSON, or a URL.

To go the other way, paste the Base64 string into the Base64 Decoder and decode it back to the original text or file.

Base64 or URL encoding — which one?

Base64 is not the same as URL encoding:

Encoding	Used for	Example
Base64	Binary to text (images, files)	dG9vbHBpbG90
URL encoding	Special characters in a URL	hello world → hello%20world

If your data contains spaces, &, or ? inside a link, use the URL Encoder instead of Base64.

Base64 in APIs and JSON

Many APIs accept Base64-encoded files:

• Images — upload an avatar as a Base64 string inside a JSON body.
• PDFs and documents — send a Base64 file in a webhook payload.
• Snippets — encode small executable scripts for testing.

When you decode an API response, paste the string into the Base64 Decoder to extract the original file. For cleaning up the surrounding JSON, format it first with the JSON Formatter.

FAQ

Is Base64 encryption? No. Base64 is encoding, not encryption. Anyone can decode it. It only changes how the data is represented, not its security.

Does Base64 make data smaller? No — it makes it about 33% larger (3 bytes become 4 characters).

Why does a Base64 string end with = The = sign is padding, added when the data length is not a multiple of 3. Not every Base64 string has it.

I decoded a file and got a blank image. What went wrong? The file may be corrupt, or you copied only part of the string. Decode the complete string; if it is an image, copy the full data:image/...;base64,... or the entire Base64 block.

Encode, decode, and verify your data with the free Base64 Encoder and Base64 Decoder — everything runs in your browser.