Base64 Encoder Decoder

About Base64 Encoding and Decoding

Base64 is an encoding scheme that converts binary data into a stream of ASCII characters. It uses a set of 64 characters (A–Z, a–z, 0–9, plus + and /, with = for padding) so that binary content can be safely transmitted or stored in systems that only support text. This tool encodes text or decoded Base64 strings in your browser; your data is not sent to a server.

How to Use

For encoding, enter or paste the text you want to convert. The tool outputs the Base64 string, which you can copy or download. For decoding, paste a Base64 string and the tool attempts to decode it back to readable text. Invalid Base64 may produce errors or garbled output. Choose the operation (encode or decode) and ensure the input matches that operation.

• Select encode or decode.
• Enter or paste the input (plain text for encoding, Base64 for decoding).
• Copy or use the result as needed.

Where Base64 Is Used

Base64 is common in email (MIME attachments), web APIs (e.g. JSON payloads carrying binary data), Data URLs (embedding images in HTML or CSS), Basic Auth (credentials in HTTP headers), and certificates and tokens (e.g. JWT segments). It is not encryption; it is encoding. Anyone can decode Base64, so do not use it to hide sensitive data. Use proper encryption for secrets.

How Base64 Works

Binary data is read in groups of 3 bytes (24 bits). Those 24 bits are split into four 6-bit values, each mapped to one of the 64 characters. So every 3 bytes become 4 Base64 characters, leading to about 33% size increase. If the data length is not a multiple of 3, padding (=) is added so the decoder can handle it correctly. Decoding reverses the process: four characters become three bytes.

Encoding vs. Encryption

Encoding changes the representation of data so it can be stored or transmitted; it does not require a key and can be reversed by anyone. Encryption scrambles data so that only someone with the correct key can recover it. Base64 is encoding only. Do not rely on it for confidentiality or integrity; use encryption and authentication (e.g. TLS, AES, HMAC) for sensitive or regulated data.

Character Sets and Compatibility

The standard Base64 alphabet is safe for URLs in many contexts, but + and / can be problematic in query strings or some systems. Variants such as Base64url replace these with - and _ and omit padding when needed. If you are integrating with an API or storage system, check whether it expects standard Base64 or a URL-safe variant.

How to Use This Base64 Encoder

Paste text or (where supported) upload or paste binary data. Click Encode to get the Base64 string, or Decode to convert a Base64 string back to text or binary. Encoding increases size by about one-third; decoding reverses it. Use it for embedding small images in HTML or CSS, sending binary in JSON, or testing APIs that expect Base64. Do not use Base64 for secrets—it is encoding, not encryption. For sensitive data, use proper encryption (e.g. AES) and secure key management.

When Base64 Is Used

Base64 is common in email attachments (MIME), data URIs in web pages, JWT tokens, and APIs that carry binary. Many programming languages have built-in Base64 support; this tool is handy for quick checks or when you do not have code at hand. For large or repeated operations, use a library in your application to avoid pasting sensitive data into a browser.

How Base64 Encoding and Decoding Work

Encoding: the input (text or binary) is split into 6-bit groups. Each group is mapped to a character in the Base64 alphabet (A–Z, a–z, 0–9, +, /). If the input length is not a multiple of 3 bytes, padding (usually =) is added so the output length is a multiple of 4. Decoding reverses this: each Base64 character is converted back to 6 bits, then the bits are regrouped into bytes. The result is the original data (or text, when interpreted with the correct encoding such as UTF-8). This tool runs in the browser; your data is not sent to a server. For Base64url (URL-safe), + and / are replaced with - and _ and padding may be omitted. This tool is for informational and general use only.

Limitations and Tips

Base64 increases size by about one-third; it is not compression. Do not use it for passwords or secrets—it is encoding, not encryption. For text, ensure you use the same character encoding (e.g. UTF-8) when encoding and decoding. Invalid Base64 input may cause decode errors or garbage output. This tool is for informational use only; for production use validated libraries and secure handling of data.

Disclaimer

This tool is for informational and general use. Decoded content may include sensitive information; avoid pasting confidential data in shared or unsecured environments. For production systems, consider validated libraries and secure handling of inputs and outputs. Base64 does not provide confidentiality or integrity.