What is Base64 encoding?

Base64 is a binary-to-text encoding scheme that represents binary data using only 64 printable ASCII characters: A–Z, a–z, 0–9, and two symbols (+ and / in standard mode). It is used to transmit binary data — like images, files, or keys — through systems that only handle text, such as email (MIME), JSON, XML, and HTML.

What is the difference between standard and URL-safe Base64?

Standard Base64 (RFC 4648 §4) uses + and / as the 62nd and 63rd characters, and = for padding. URL-safe Base64 (RFC 4648 §5) replaces + with - and / with _ so the output is safe in URLs and filenames without percent-encoding. URL-safe Base64 also omits the = padding. Use URL-safe when the Base64 string will appear in a URL query parameter, path segment, or filename.

How do I decode a Base64 string?

Switch to "Base64 → Text" mode, paste your Base64 string, and select the correct charset (Standard or URL-safe). The tool decodes it instantly and displays the original text. If the string uses - and _ instead of + and /, select URL-safe mode.

Does Base64 encoding work on Unicode and emoji?

Yes. This tool uses the TextEncoder API to first convert your text to UTF-8 bytes, then encodes those bytes as Base64. This correctly handles any Unicode character — accented letters, CJK characters, Arabic script, emoji, and symbols. The decoder reverses this process using TextDecoder with UTF-8.

Why is the Base64 output longer than the input?

Base64 encodes every 3 bytes of input as 4 characters of output, which means the output is approximately 33% larger than the input. For example, 3 bytes → 4 characters, 6 bytes → 8 characters. This size overhead is the trade-off for making binary data representable as plain text.

Is this tool safe? Is my data sent anywhere?

Yes, completely safe. All encoding and decoding happens entirely in your browser using the built-in btoa() and atob() JavaScript functions and the TextEncoder/TextDecoder APIs. No data is uploaded, stored, or transmitted to any server.

Workspace

Mode

Charset

Text to encode

Base64 output

Base64 output appears here

Quick reference

Standard Base64

Uses A–Z, a–z, 0–9, +, /, = (padding). RFC 4648 §4.

URL-safe Base64

Replaces + → -, / → _, omits = padding. RFC 4648 §5. Safe in URLs and filenames.

Encoding ratio

Base64 output is ~33% larger than the input (every 3 bytes → 4 chars).

UTF-8 support

This tool handles full Unicode — emoji, accented letters, CJK characters all encode correctly.

Letters to Numbers

Trusted Conversion Tools

Base64 Encoder and Decoder

Our free Base64 Encoder and Decoder converts any text to Base64 format or decodes Base64 strings back to readable text — instantly, in your browser, with no uploads. It supports both standard Base64 (RFC 4648 §4, using +/= characters) and URL-safe Base64 (RFC 4648 §5, using -_ with no padding), handles full UTF-8 including emoji and Unicode, and shows input/output character counts with the encoding ratio. A built-in reference explains the difference between the two variants and when to use each.

Who Is It For?

Developers & Engineers

Encoding API keys, tokens, binary payloads, and credentials for use in HTTP headers, JSON configs, or environment variables.

Security Analysts

Decoding Base64-encoded payloads found in malware samples, phishing emails, SAML assertions, or JWT tokens during security analysis.

Web Developers

Encoding images or fonts as Base64 data URIs for embedding directly in HTML/CSS, or decoding Base64 strings from API responses.

DevOps & SREs

Decoding Kubernetes secrets (which are Base64-encoded), Docker credentials, or TLS certificate data stored in base64 format.

Students & Learners

Understanding how Base64 encoding works as a fundamental part of learning about data encoding, email protocols (MIME), and web security.

How It Works

Select a mode (Encode or Decode) and a charset (Standard or URL-safe). In Encode mode, type or paste any text — the tool converts it to UTF-8 bytes first, then produces the Base64 string instantly. In Decode mode, paste a Base64 string and the tool reverses the process, decoding the bytes back to readable UTF-8 text. Switch to URL-safe mode when your Base64 output will appear in a URL or filename — it replaces + with -, / with _, and omits = padding.

Features

Encode any text to Standard Base64 (RFC 4648 §4)
Encode to URL-safe Base64 (RFC 4648 §5) with - and _ instead of + and /
Decode Standard and URL-safe Base64 back to text
Full UTF-8 support — handles emoji, accented letters, CJK, and all Unicode
Shows input/output character counts and encoding size ratio
Swap button to instantly flip encode ↔ decode with current output
Clear error messages for invalid Base64 input
100% browser-based — no data leaves your device

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Your Privacy Matters

All processing happens in your browser. We never store, send, or log your data. Completely private and secure.