Base64 Encoder / Decoder
Encode plain text to Base64 or decode Base64 strings back to readable text. Full UTF-8 support with instant conversion — all processing happens in your browser.
Base64 Encoder / Decoder — Encode & Decode Base64 Online Free: Free Base64 Encoder / Decoder tool: encode text to Base64 or decode Base64 strings back to plain text instantly. Supports UTF-8, file encoding, and data.
How to Encode and Decode Base64
Paste Your Input
Enter the text you want to encode, or paste a Base64-encoded string you need to decode. The tool handles both directions.
Click Encode or Decode
Click "Encode to Base64" to convert plain text, or "Decode from Base64" to convert back. Results appear instantly in the output box.
Copy the Result
Use the Copy button or Swap button to move the output back to input for chained operations. Input and output lengths are displayed for reference.
What Is Base64 Encoding?
Base64 is a binary-to-text encoding scheme that converts binary data into a string of ASCII characters. It uses a set of 64 characters — the letters A-Z, a-z, digits 0-9, and the symbols + and / — to represent arbitrary binary data in a format that's safe to transmit through text-based systems like email, URLs, and JSON payloads.
The most common real-world use case developers encounter is embedding small images or files directly in HTML
or CSS. Instead of linking to an external image file, you can convert the image to a Base64 string and use
it as a data URI: data:image/png;base64,iVBOR.... This eliminates an extra HTTP request, which
can improve page load performance for small assets like icons.
Email attachments use Base64 internally — when you attach a PDF or image to an email, the MIME standard encodes the file's binary content as Base64 text so it can travel through email protocols that only support ASCII. Your email client handles the encoding and decoding transparently, but if you've ever had to debug email delivery issues, you've probably seen raw Base64 blocks in message headers.
A critical thing to understand about Base64: it is not encryption. The encoded text is trivially reversible — anyone with a Base64 decoder can read the original content. It's purely a format conversion, not a security measure. Never use Base64 to "hide" sensitive data like passwords, API keys, or personal information. Despite this, it shows up incorrectly in security contexts regularly, which has led to numerous data exposure incidents.
Base64 encoding increases the data size by approximately 33%. A 100-byte input becomes roughly 133 characters of Base64 output. This is the trade-off for text-safe encoding — you gain compatibility with text-only channels at the cost of increased payload size. For this reason, Base64 encoding large files (videos, high-resolution images) is generally impractical and wasteful. It's best suited for small payloads, inline assets, and protocol requirements.
Why Use Our Base64 Tool?
Full UTF-8 Support
Unlike basic Base64 tools that break on emojis and non-Latin characters, our encoder handles the full Unicode range through proper UTF-8 encoding before Base64 conversion.
Size Analytics
See exactly how encoding changes your data size. The tool shows input length, output length, and the percentage size difference — useful for payload optimization decisions.
Swap & Chain
The Swap button moves output back to input, letting you chain operations or verify round-trip encoding. Encode → Decode should always return your original text.
Browser-Only
All encoding and decoding happens locally using JavaScript's built-in btoa/atob functions with a UTF-8 wrapper. Your data stays in your browser — nothing is transmitted.
Frequently Asked Questions
No — and this is a critical distinction. Base64 encoding is a reversible format conversion, not a security mechanism. Anyone can decode a Base64 string without any key or password. It's designed for data transport compatibility, not confidentiality. Never use Base64 to protect sensitive information. Use actual encryption (AES, RSA) for security.
Base64 represents every 3 bytes of input as 4 ASCII characters, resulting in a ~33% size increase. This overhead is the cost of converting binary data into a text-safe format. The 64-character alphabet (6 bits per character vs. 8 bits per byte) means you need more characters to represent the same amount of information.
Yes. Our tool uses a UTF-8 encoding wrapper around the standard btoa function, so emojis, Chinese characters, Arabic text, and any other Unicode content will encode and decode correctly. The basic JavaScript btoa function alone fails on non-ASCII characters, which is why we add the UTF-8 conversion step.
Common legitimate uses include embedding small images as data URIs in CSS/HTML, encoding binary data in JSON payloads (which only support text), transmitting binary content through text-only APIs, and encoding authentication tokens in HTTP headers (like Basic Auth, which uses Base64). Avoid it for large files or as a security measure.
There's no hard limit in the tool itself, but browser performance will degrade with very large inputs (several megabytes). For text encoding, inputs up to a few hundred kilobytes process instantly. For larger payloads, consider using a command-line tool or programming language library instead.