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.

Frequently Asked Questions

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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