Online base64 decode tool

The online base64 decoding tool provides base64 encoding, online base64 decoding and base64 encryption and decryption: it encrypts a string into Base64 format and decodes Base64 back into plain text. Base64 is a fairly common online encryption algorithm; when fixing garbled Chinese text, encoding the text in different ways can effectively avoid the garbling. This site does not record any of your information, so use it with confidence.

Base64 index table

Base64 encoding uses 64 printable ASCII characters (A-Z, a-z, 0-9, +, /) to encode any byte sequence into an ASCII string, with the “=” symbol used as a suffix.

ValueCharacterValueCharacterValueCharacterValueCharacter
0A16Q32g48w
1B17R33h49x
2C18S34i50y
3D19T35j51z
4E20U36k520
5F21V37l531
6G22W38m542
7H23X39n553
8I24Y40o564
9J25Z41p575
10K26a42q586
11L27b43r597
12M28c44s608
13N29d45t619
14O30e46u62+
15P31f47v63/

  Base64 splits the input string byte by byte, takes the binary value of each byte (padding the high-order bits with 0 if it has fewer than 8 bits), concatenates these binary values and then splits them into groups of 6 bits (because 2^6=64), padding the last group with 0 at the end if it has fewer than 6 bits. Each group of binary values is converted to decimal, and the corresponding symbols from the table above, concatenated in order, give the Base64 encoded result.

  Base64 can be used as low-level binary encoding of arbitrary data for situations that only transmit ASCII characters. It is most often used for transferring text data: in MIME-formatted email, Base64 can encode the message content so it transfers between computers of different languages without garbled characters. Note that this is about transmission, not display: on Western European computers utf-8 encoding displays Chinese normally (with the matching font installed), but it may not transmit Chinese correctly, and converting to Base64 removes this concern.

Base64 encoding: unless otherwise specified, non-ASCII characters are conventionally encoded using the UTF-8 character set.

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How to use

This tool belongs to the “Encryption & encoding” category.

  1. 1Pick an algorithm: reversible ones are AES, DES and RC4; one-way digests are MD5 and the SHA family.
  2. 2Enter the text plus your key or salt. Encrypting twice with the same key must give the same result.
  3. 3Copy the output into your code. When comparing digests, match case and the 16/32-bit variant first.

Your input is processed locally in the browser whenever possible. We do not store it.

Frequently asked questions

Can MD5 be decrypted?

No. MD5 is a one-way digest — you can compare it, never reverse it. So-called "decryption" is a rainbow-table hit.

Why do two runs give different results?

Salts, random IVs, or a different case or source encoding all change the output. Normalise to UTF-8 before comparing.

Is it safe to paste a real key here?

Use it for learning and format checks. Generate and store production keys server-side; never paste a live secret into a web page.