Base64 Encoder / Decoder

Encode plain text to Base64 or decode Base64 strings back instantly.

Loading ratings...

Rate this tool

Quick Answer

Base64 is a method of representing binary data as ASCII text using 64 characters. It is encoding, not encryption — anyone can decode it.

What Is Base64 Encoder / Decoder?

Base64 Encoder / Decoder is a free online developer tools tool that encode plain text to base64 or decode base64 strings back instantly. Base64 is a way to represent binary data as ASCII text using 64 safe characters (A–Z, a–z, 0–9, +, /, and = for padding). It is not encryption — anyone with the encoded string can decode it. Its purpose is to let binary data travel through systems that only handle text, such as email attachments, data URIs in HTML, and HTTP headers. This tool encodes plain text to Base64 or decodes a Base64 string back to the original text. It handles UTF-8, so accented characters and emojis work correctly. A common pitfall is thinking Base64 compresses data: it actually expands it by about 33%. Also, Base64 is not a security measure — if you need confidentiality, use actual encryption before encoding. Everything runs in your browser, so your input stays on your device. Unlike many similar tools, it runs entirely in your browser — no data is sent to any server, no account is required, and there are no usage limits. Whether you are a developer, writer, SEO professional, or casual user, this tool provides instant, accurate results without friction.

base64 encoderbase64 decoderbase64 encode decodeencode base64 onlinedecode base64 stringbase64 converter freebase64 to text

How to Use Base64 Encoder / Decoder

Paste the text or Base64 string, pick encode or decode, and the result appears instantly. Copy it or use it directly. All processing is client-side.

Key Features

Encode and decode in one place
Handles UTF-8 text including emoji and accented characters
Copy result to clipboard
Fully client-side, nothing uploaded

Common Use Cases

Encoding credentials or tokens for basic auth headers
Building data URIs for inline images or fonts in HTML
Decoding JWT payloads or Base64-encoded tokens during debugging

Common Mistakes to Avoid

Thinking Base64 is encryption or obfuscation
Assuming Base64 compresses data (it grows it ~33%)
Pasting corrupted Base64 with bad padding (missing = signs)

Common Questions About Base64 Encoder / Decoder

Is Base64 secure?

No. Base64 is not encryption. It only changes the representation of the data. Never use it to protect secrets.

Does Base64 compress data?

No. It expands the data by roughly one third. A 100 KB file becomes about 133 KB when Base64-encoded.

Related Tools & Resources

Image to Base64
Data URI Maker
URL Encoder

Best Practices for Base64 Encoder / Decoder

To get the most out of Base64 Encoder / Decoder, follow these best practices. Ensure your input data is clean and properly formatted for the most accurate results. Use the copy function to transfer output directly to your clipboard. Bookmark the tool for easy access. Check the related tools section below for complementary utilities that can enhance your workflow. Remember that all processing is client-side, so your data never leaves your browser.

More Encoding & Encryption Tools

Base64 Encoder / Decoder is part of the Encoding & Encryption Tools topic. Explore related tools in this cluster:

Privacy & Security

Base64 Encoder / Decoder processes all data entirely within your browser using JavaScript. No text, files, or personal information is transmitted to any server. Your data stays on your device, making this tool safe for sensitive content. We do not track usage, store inputs, or share data with third parties. The tool works offline after the initial page load and requires no account to use.

Frequently Asked Questions

Find answers to common questions about this tool.

Why does my Base64 output contain "=" at the end?

The "=" padding character indicates the input length was not a multiple of 3 bytes. Base64 encodes 3 bytes into 4 characters, and padding is added for the final block.

What is the difference between Base64 and Base64URL?

Base64URL uses "-" instead of "+" and "_" instead of "/" to make the output URL-safe without percent-encoding. This tool supports both formats.

Can I encode a file without sending it to a server?

Yes. The Base64 Encoder runs entirely in your browser. Files are read locally using the FileReader API and never transmitted to any server.

Why does my decoded Base64 output show garbled characters?

The decoded output may not be UTF-8 text. Base64 can encode any binary data. Try saving the decoded output as a file or checking if the original data was binary.

What is the size overhead when encoding to Base64?

Base64 increases data size by approximately 33%. Every 3 bytes of input becomes 4 characters of output. For large files, consider whether the convenience is worth the size increase.

Resources

Topic Cluster

Base64 encoder/decoder, URL encoder, Caesar cipher, text obfuscator, and JWT decoder for encoding, encryption, and cipher operations.

Browse all Encoding & Encryption Tools

5 tools in this topic

About Testrefy

All tools run entirely in your browser. No data is sent to any server. 100% private and free.

Browse all tools