Base64 Encoder/Decoder

Base64 encode and decode online. Convert text to Base64 or decode Base64 strings back to plain text. View size comparison and encoding ratio.

Text → Base64

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APIPOST /api/v1/util/base64
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Try also: URL Encoder/Decoder
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Key Features

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Real-time analysis with detailed output

REST API Access

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Accurate Data

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What is Base64 Encoder/Decoder?

The Base64 encoder and decoder converts text and binary data to Base64 encoding and back. Base64 transforms any data into a string of 64 safe ASCII characters (A-Z, a-z, 0-9, +, /), making it suitable for transmission through text-only channels. It is widely used in web development for embedding data in JSON and XML payloads, encoding email attachments (MIME), storing binary data in databases as text, passing data in URL parameters (URL-safe Base64 variant), and embedding images in CSS and HTML as data URIs.

The tool shows a real-time size comparison between original and encoded data so you can see the 33% size overhead. This free online Base64 converter processes everything in your browser — nothing is sent to any server, making it safe for encoding sensitive data like API keys and authentication tokens.

How to Use

  1. 1Enter or paste the text you want to encode or decode
  2. 2Select mode: Encode (text to Base64) or Decode (Base64 to text)
  3. 3The result appears instantly as you type — no need to click a button
  4. 4Review the size comparison: original bytes vs encoded bytes and the encoding ratio
  5. 5Copy the output with one click for use in your code, API, or configuration

Who Uses This

System Administrators

Monitor and troubleshoot infrastructure

Developers

Debug network issues and integrate via API

SEO Specialists

Verify domain configuration and performance

Security Analysts

Audit and assess network security

Frequently Asked Questions

What is Base64 encoding and when is it used?
Base64 is a binary-to-text encoding scheme that represents any data using 64 safe ASCII characters: A-Z, a-z, 0-9, plus (+), and slash (/), with equals (=) for padding. It's used whenever binary or non-ASCII data needs to travel through text-only channels: email attachments (MIME encoding), embedding images in CSS/HTML as data URIs, passing binary data in JSON API payloads, storing binary data as text in databases, encoding authentication credentials in HTTP headers (Basic Auth), and transmitting data in URLs (URL-safe Base64 variant uses - and _ instead of + and /).
How do I decode a Base64 string back to readable text?
Paste the Base64-encoded string into the tool and select Decode mode. The original text is displayed instantly. The tool handles both standard Base64 (using + and /) and URL-safe Base64 (using - and _). If decoding produces garbled text, the original data may have been binary (like an image or file) rather than text, or it may use a different character encoding than UTF-8. Base64 decoding is deterministic — the same Base64 string always decodes to the same original data.
Why is Base64-encoded data larger than the original?
Base64 increases data size by approximately 33% because of how the encoding works: every 3 bytes of original data (24 bits) are split into 4 groups of 6 bits, and each 6-bit group maps to one Base64 character (1 byte). So 3 bytes become 4 bytes — a 33% increase. Additionally, padding characters (=) are added when the input length isn't a multiple of 3. This size overhead is the tradeoff for being able to safely represent any binary data as printable ASCII text.
Is Base64 encryption? Is it secure?
No — Base64 is encoding, not encryption. It does not provide any security. Anyone with the Base64 string can decode it back to the original data instantly without any key or password. Base64 is purely a data representation format for compatibility with text-based systems, not a protection mechanism. Never use Base64 to 'hide' sensitive data like passwords or API secrets — use proper encryption (AES, RSA) for security. However, encoding data in Base64 in this tool is safe because processing happens entirely in your browser.
What is the difference between Base64 and Base64URL?
Standard Base64 uses the characters + and / which have special meaning in URLs (+ means space, / is a path separator). Base64URL is a variant that replaces + with - (hyphen) and / with _ (underscore), making the output safe for use in URLs, filenames, and query parameters without additional encoding. Base64URL also typically omits the trailing = padding characters. JSON Web Tokens (JWTs) use Base64URL encoding, as do many API authentication schemes.

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API Endpoint

POST /api/v1/util/base64
View Documentation