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Base64 Encoder/Decoder

Input
Output

Online Base64 encoder/decoder. Convert between text and Base64, runs entirely in the browser — data never leaves your device.

How to Use & FAQ5 steps · 8 Q&A

Base64 Encoder/Decoder

Online Base64 encoder/decoder. Convert between text and Base64, runs entirely in the browser — data never leaves your device.

How to Use

  1. Choose Encode or Decode modeEncode is the default: it turns plain text into Base64. If you have a Base64 string to restore, switch to Decode.
  2. Paste or type text into the input boxPlain text and existing Base64 strings are both supported. Characters such as Chinese or emoji are first turned into UTF-8 bytes before processing.
  3. View the output in real timeThe result appears immediately in the output box. Encoding grows size by about 33%; garbled decode output usually means an encoding mismatch at the source.
  4. Copy, export, or keep processingClick Copy to export the result with one click; click Swap to send the output back to the input for chained or iterative processing.
  5. Tips for multiple pieces of contentBase64 carries no structural information, so process pieces one at a time. If your text has line breaks, decide whether to keep them — they affect decoding.

Related tools

URL Encoder/DecoderSymmetric EncryptionAsymmetric EncryptionHashing

Related reading

Character Encoding and UTF-8: Why Text Turns into GibberishURL Encoding: When You Need It, and Where %20 and + Come FromBase64 Is Not Encryption: Encoding vs EncryptionWhat Is Really Inside a JWT (and Three Fatal Mistakes)

FAQ

Is Base64 encryption?

No. Base64 is just an encoding that converts binary data into printable characters. The process is fully reversible and contains no key, so anyone can decode it. It is used to safely transmit data where binary is not supported — it is not a substitute for encryption. If you want to keep content private, use symmetric encryption such as AES instead of Base64.

Does the online Base64 tool save my content?

No. This tool runs entirely in your browser — neither input nor output is uploaded to any server. It is suitable for ordinary text, but do not use it for genuinely sensitive data, because Base64 provides no confidentiality at all: anyone who gets the output can decode it immediately.

Why does Chinese text appear garbled after decoding?

It is usually caused by a character-encoding mismatch. Base64 encodes bytes, not characters: Chinese text is first turned into bytes by some encoding (UTF-8, GBK, etc.), then Base64-encoded. This tool processes text as UTF-8 by default; if the source used another encoding (e.g. GBK), convert it to UTF-8 first, otherwise the result is garbled.

Why does Base64 output get longer?

Base64 represents 3 bytes with 4 characters, so the size grows by about 33%. Padding "=" and line breaks add a little more. This is a normal cost of the encoding, independent of the content. To save space, consider compression (e.g. gzip) rather than Base64.

Can Base64 be placed directly in a URL?

Not recommended. Standard Base64 contains + / =, which may be escaped or truncated in a URL. Use URL-safe Base64 instead (+ to -, / to _, and drop =). The third segment of a JWT uses exactly this URL-safe form.

What is embedding images as Base64 used for?

It lets you inline small icons into HTML/CSS (data URI) to avoid an extra request; however the size grows by about 33%, so it is unsuitable for large images. Rule of thumb: inline only tiny icons under a few KB; serve large images as separate files.

When should I use Base64, and when should I avoid it?

Use it when you must carry binary data through a text-only channel such as JSON, XML, email or a URL (e.g. inline icons, JWT, attachments). Avoid it when you want to hide or encrypt data, when encoding large files, or when storing large Base64 blobs in a database (it wastes space and is hard to query).

Can Base64 compress data and save space?

No. Base64 actually makes data about 33% larger; it only solves how to represent binary inside a text environment, not the size problem. Use a real compression algorithm when you need to save space.