What is Base64 used for?

Base64 is used wherever binary data must travel through text-only systems. Common uses include embedding images directly in HTML or CSS as data URIs, encoding email attachments in MIME format, transmitting binary payloads in JSON APIs, storing binary data in XML, and encoding credentials in HTTP Basic Authentication headers. It is also widely used in JWTs (JSON Web Tokens) to encode the header and payload.

Is Base64 the same as encryption?

No. Base64 is encoding, not encryption. Anyone can decode a Base64 string instantly without a key — there is no secret involved. Encryption transforms data so only authorized parties can read it. Base64 simply changes how data is represented. Treating Base64 as a security measure is a common and dangerous mistake. If you need to protect data, use proper encryption algorithms like AES.

Can Base64 encoded data always be decoded?

Yes — any valid Base64 string can be fully decoded back to its original binary data. Base64 is completely reversible, unlike hashing. However, the decoded output may be raw binary rather than readable text depending on the original input. If the source was a text string encoded as UTF-8, the decoded result will be readable. If it was a binary file, the output will be binary data.

What is the difference between Base64 and Base64URL?

Standard Base64 uses + and / characters, which have special meaning in URLs. Base64URL is a URL-safe variant that replaces + with - and / with _, and typically omits padding = characters. Base64URL is used in JWTs, OAuth tokens, and anywhere Base64 data appears in URLs or filenames. Our tool uses standard Base64 encoding.

Why does Base64 end with == or =?

Base64 encodes data in groups of 3 bytes into 4 characters. When the input length is not a multiple of 3, padding characters (=) are added to complete the final group. One = means the last group had 2 bytes; == means it had 1 byte. Padding ensures the encoded string length is always a multiple of 4, which simplifies decoding.

Does Base64 increase file size?

Yes. Base64 encoding increases data size by approximately 33% because it represents every 3 bytes as 4 ASCII characters. For example, a 100KB image becomes roughly 133KB when Base64-encoded. This overhead is acceptable for small assets like icons embedded in CSS or HTML, but makes Base64 impractical for large files where bandwidth and performance matter.

Base64 Encoder & Decoder - Encode and Decode Online

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Base64 Encoding / Decoding

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Privacy Notice

All encoding and decoding is performed locally in your browser using JavaScript. No input data is sent to any server, stored, or logged. Miracle Salad does not collect or retain any content entered into this tool.

About Base64 Encoding

Base64 turns arbitrary binary data into plain text made of 64 safe characters. That is its entire job. It is not compression — the output is larger, not smaller. And it is not encryption, although it is mistaken for it constantly. It exists because a great many channels can carry text but choke on raw bytes.

How to use this tool

1 Choose Encode or Decode, then paste your text — or switch to file mode and drop a file in.
2 The result appears as you type; nothing is uploaded and no button press is needed.
3 When decoding into a file, type the extension so the preview and download know what they are handling.

Base64 is not encryption

This is the point worth remembering above all others. Base64 has no key and no secret; the transformation is public and reversible by anyone, as this page demonstrates in a single click. Text that merely looks scrambled offers no protection at all. If you find a password, an API key or a token stored as Base64, treat it as if it were written in plain sight — because it is. Use real encryption when the goal is secrecy, and use Base64 only when the goal is safe transport.

Why it exists at all

Many systems were designed for text and only text. Email bodies, JSON payloads, XML documents, URLs and HTML attributes all break when a raw byte happens to look like a control character or a quotation mark. Base64 sidesteps the problem by mapping every possible byte onto a small alphabet of letters, digits and two punctuation marks that survive any of these channels intact. That is why you meet it in email attachments, in data URIs that embed a small icon directly in a stylesheet, and in the middle segment of every JWT.

The price is about a third more

Three bytes of input become four characters of output, so the result is roughly 33% larger than what you started with. For a short token that is irrelevant. For a large image inlined into a stylesheet it is not: the file grows, it cannot be cached separately from the page, and the browser must decode it before it can paint. Inline small assets if it saves a request, keep large ones as ordinary files, and remember that Base64 never makes anything smaller — if size is your problem, compression is the tool you want.

Frequently Asked Questions about Base64

Base64 is a binary-to-text encoding scheme that represents binary data using 64 printable ASCII characters (A–Z, a–z, 0–9, +, /). It converts every 3 bytes of binary data into 4 ASCII characters, increasing size by ~33%. Base64 is not encryption — it provides no security. Its purpose is safe transmission of binary data through text-based channels like email, JSON, or HTML attributes.

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PDF to Base64 Convert a PDF to Base64 for APIs that accept documents as text. Get the raw string, a data URI and an HTML embed snippet - all in your browser, nothing uploaded.

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PDF to Base64 Convert a PDF to Base64 for APIs that accept documents as text. Get the raw string, a data URI and an HTML embed snippet - all in your browser, nothing uploaded.

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PNG to Base64 Convert a PNG to Base64 and get a ready-to-paste data URI, the raw string and a CSS snippet. Runs entirely in your browser - the image is never uploaded.

JPG to Base64 Convert a JPG or JPEG photo to Base64 and get a data URI, the raw string and a CSS snippet. Runs in your browser - and tells you honestly when inlining is the wrong choice.

WebP to Base64 Convert a WebP image to Base64 and get a data URI, the raw string and a CSS snippet. Runs in your browser - and explains the fallback you give up by inlining.

PDF to Base64 Convert a PDF to Base64 for APIs that accept documents as text. Get the raw string, a data URI and an HTML embed snippet - all in your browser, nothing uploaded.

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