Base64 Encoder / Decoder

Encode and decode Base64 text

0 -> 0
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Output

Tool guide

About Base64 Encoder / Decoder

A Base64 encoder and decoder converts UTF-8 text into Base64 and decodes Base64 back into readable text.

This tool supports regular Base64 and URL-safe Base64, validates bad input, and runs the conversion locally in your browser.

How to use the Base64 Encoder/Decoder

  1. Paste plain UTF-8 text and click Encode to produce a Base64 string.
  2. Paste a Base64 value and click Decode to turn it back into readable text.
  3. Enable URL-safe Base64 when the value will be placed in a URL, token segment, or filename-like field.
  4. Use Swap when you want to move the output back into the input for the next conversion.

When you would use it

  • Decode a token segment, config value, or API payload while debugging.
  • Encode short text into Base64 before placing it in a test fixture or documentation example.
  • Check whether a copied Base64 value is valid before sending it to another service.
  • Convert between standard and URL-safe variants when working with web tokens or URL parameters.

Base64, URL-safe Base64, and padding

Base64 represents bytes using printable characters. It is an encoding format, not encryption, so anyone can decode it if they have the text.

  • Standard Base64 uses letters, numbers, plus, slash, and optional equals padding.
  • URL-safe Base64 replaces plus with hyphen and slash with underscore so the value survives URLs more easily.
  • Padding: equals signs at the end help align the byte length; some URL-safe formats omit them.
  • UTF-8 text: non-English characters are encoded as bytes first, then represented as Base64.

Base64 Encoder/Decoder FAQ

Is Base64 encryption?
No. Base64 is reversible encoding, not encryption. It hides nothing from anyone who can decode the text.
Why does decoding fail?
The input may contain invalid characters, missing bytes, wrong URL-safe mode, or copied whitespace that changes the value.
When should I use URL-safe Base64?
Use it when the encoded value needs to appear in URLs, JWT-like token segments, or filenames where plus and slash can cause trouble.
Does Base64 make data smaller?
No. Base64 usually increases size by about one third because binary bytes are represented as printable text.
Is my Base64 text uploaded?
No. Encoding and decoding run locally in the browser and the input is not uploaded to wetool.site.

Base64 vs URL encoding

Base64 is for representing bytes as text. URL encoding is for escaping characters inside a URL. If you put Base64 inside a query string, URL-safe Base64 is usually easier to handle than standard Base64.

Standard Base64 vs URL-safe Base64

When Base64 appears in URLs, JWTs, filenames, or form fields, the common failures are the alphabet variant and padding.

  • Standard Base64 uses + and /; it usually needs URL encoding before being placed in a query string.
  • URL-safe Base64 uses - and _, and is common in JWTs, OAuth state values, short tokens, and filename-like fields.
  • Some protocols keep trailing = padding and others omit it; when decoding fails, first check whether the length must be padded to a multiple of 4.

Base64 security boundary

Base64 is encoding, not encryption. It turns binary or UTF-8 text into printable characters, but it does not hide the content.

  • Anyone with the Base64 string can decode it, so do not treat secrets, passwords, or private keys as protected data just because they are encoded.
  • When decoding JWT payloads, Basic Auth headers, or config values, assume the content may be sensitive before pasting it into logs or tickets.
  • Use real encryption for confidentiality, signatures for authenticity, and hashes for integrity; Base64 is only a representation layer.

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