What is Base64 used for?

Base64 is used to encode binary data as text for safe transmission over text-based protocols. Common uses include embedding images in HTML/CSS (data URIs), encoding JWT tokens, email attachments, and API authentication headers.

Is Base64 encoding the same as encryption?

No. Base64 is encoding, not encryption. Anyone can decode a Base64 string without a key. It's designed for data transport, not security. Use AES encryption if you need actual security.

Does Base64 increase the size of my data?

Yes, Base64 encoding increases data size by approximately 33% because every 3 bytes of input becomes 4 bytes of output. This is an inherent trade-off for making binary data text-safe.

Why are there = signs at the end of Base64 strings?

The = characters are padding. Base64 works in groups of 3 bytes producing 4 characters. If your input isn't a multiple of 3 bytes, padding characters (=) are added to make the output length a multiple of 4.

What is the difference between standard and URL-safe Base64?

Standard Base64 uses +, /, and = padding, which are reserved or awkward inside URLs and JWTs. URL-safe Base64 (base64url) replaces + with - and / with _ and drops the = padding. Use it for JWT payloads, query parameters, and anywhere the string ends up inside a URL — this tool outputs it when you tick URL-safe and auto-detects it when decoding.

Why do I see an error decoding Base64 for an image or file?

That Base64 decodes to raw binary bytes, and this tool renders text. When the bytes aren't valid UTF-8, the browser can't show them and the tool reports an error instead of printing replacement characters. For images and archives, use a dedicated binary tool — here, text, JSON, and tokens always decode exactly.

Can I decode a JWT here?

Yes, a JWT payload decodes just like any Base64 — and that's the point of caution: decoding reveals the payload as plain text (subject, expiry, claims), and this tool does not verify the signature, so treat decoded claims as untrusted. Base64 is encoding, not encryption, and never a security mechanism.

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Base64 Encoder & Decoder

Encode text to Base64 and back — URL-safe included

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Free forever — no sign-up, nothing uploaded. Files never leave your device.

braincoder.app/use/base64

Encode text to Base64 and back — URL-safe included

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About this tool

Encode text, JSON, and JWTs to standard or URL-safe Base64 and decode it back, live in your browser with nothing uploaded.

The BrainCoder Base64 Encoder & Decoder converts text to Base64 and back the moment you type — no buttons, no reloads. Encoding maps binary data onto a safe ASCII alphabet (A-Z, a-z, 0-9, +, /) so it can travel through JSON fields, HTTP headers, email attachments (MIME), and text-only database columns. Everything runs in your browser with zero server interaction — your data never leaves your machine.

Standard Base64 pads short groups with = characters. The URL-safe variant (base64url) swaps + and / for - and _, which is the format used inside JWT payloads, query strings, and data URIs — this tool detects those characters automatically when decoding.

Decoding restores the original bytes and interprets them as UTF-8 text, so plain text, JSON, and emoji round-trip exactly. If the source was a binary file such as an image or archive, the decoded bytes aren't valid UTF-8 and the tool reports that instead of printing garbage. Free, no account, works on any modern browser.

Key features

Everything you get with Base64 Encoder & Decoder — no premium upsell.

Standard Base64 encoding and decoding

URL-safe base64url output (uses “-” and “_”, no padding)

Real-time conversion as you type — no button to press

Unicode and multi-byte text round-trips exactly

One-click copy for encoded output

Fully client-side — nothing is transmitted

How to use Base64 Encoder & Decoder

Follow the steps below to use the tool.

1
Enter or paste your text
Type or paste plain text, JSON, or a JWT into the input field. The Base64 output updates instantly as you type — there is no Encode button to press.
2
Choose an output format
Standard Base64 is the default. Tick URL-safe output (uses “-” and “_”, no padding) when the string will live in a URL, query parameter, or JWT.
3
Copy the Base64 string
Click the copy button to grab the output and paste it into an HTTP header, database field, or config file.
4
Switch to Decode and paste
Toggle Decode from Base64, then paste a Base64 string. The original text appears immediately; URL-safe strings are detected automatically. If the bytes aren't valid UTF-8 text, an error explains why.

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How-to guides

How to Encode and Decode Base64 Online

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Base64 Encoder & Decoder

About this tool

Key features

How to use Base64 Encoder & Decoder

Enter or paste your text

Choose an output format

Copy the Base64 string

Switch to Decode and paste

Frequently asked questions

Related tools

How-to guides