Free Base64 Encoder & Decoder Online

Quickly encode text to Base64 or decode Base64 back to plain text with this free online tool. Supports full UTF-8 text including emoji and special characters. Everything runs in your browser — no data is sent to any server.

TL;DR: Encode text to Base64 or decode Base64 back to plain text instantly in your browser. Supports full UTF-8 including emoji. No data is sent to any server — completely private and offline-capable.

How to Use

1. To encode: Paste your plain text and click “Encode to Base64”
2. To decode: Paste Base64 string and click “Decode from Base64”
3. Use Copy Output to grab the result

What Is Base64 Encoding?

Base64 is a binary-to-text encoding scheme that converts binary data into a set of 64 printable ASCII characters (A-Z, a-z, 0-9, +, /). It’s widely used in:

• Email attachments (MIME encoding)
• Data URLs in CSS and HTML (data:image/png;base64,...)
• API authentication (HTTP Basic Auth headers)
• JWT tokens (JSON Web Tokens use Base64URL encoding)
• Embedding binary data in JSON or XML payloads

Base64 vs Other Encodings

• Base64 — 33% size overhead, uses A-Za-z0-9+/=
• Base64URL — Same but uses – and _ instead of + and / (URL-safe)
• Hex encoding — 100% size overhead, uses 0-9a-f
• URL encoding — Variable overhead, uses %XX for special chars

Privacy & Security

This Base64 tool processes everything locally in your browser using JavaScript’s built-in btoa() and atob() functions. No data is transmitted. Safe for encoding API keys, tokens, or sensitive configuration values.

Important: Base64 is encoding, not encryption. Anyone can decode Base64 data. Never use Base64 alone to protect sensitive information.

Recommended Reading

Want to understand encoding, encryption, and web security in depth?

• Encoding & Encryption Fundamentals — essential reading for understanding encoding
• HTTP: The Definitive Guide — essential reading for HTTP headers and encoding
• Cryptography Made Simple — essential reading for data encoding

Frequently Asked Questions

What is Base64 encoding used for?

Base64 converts binary data into printable ASCII characters so it can be safely transmitted through text-based protocols. Common uses include encoding email attachments (MIME), embedding images as data URIs in HTML/CSS, transmitting binary data in JSON API payloads, and encoding credentials in HTTP Basic Authentication headers.

Is Base64 the same as encryption?

No. Base64 is an encoding scheme, not encryption. Anyone can decode a Base64 string without any key or password. It provides zero confidentiality. Never use Base64 alone to protect sensitive information — use proper encryption (AES-256, ChaCha20) for that purpose.

Why does Base64 make data about 33% larger?

Base64 represents every 3 bytes of input as 4 ASCII characters. This 4:3 ratio means the output is always approximately 33% larger than the input. The tradeoff is universal compatibility with text-based systems that cannot handle raw binary data.

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

Standard Base64 uses +, /, and = characters, which have special meaning in URLs. URL-safe Base64 (Base64URL) replaces + with - and / with _, and typically omits padding. This variant is used in JWTs, URL parameters, and filename-safe contexts.

References

• RFC 4648 — The Base16, Base32, and Base64 Data Encodings — The IETF standard defining Base64 and Base64URL encoding
• MDN Web Docs — btoa() Global Function — Documentation for the browser API used for Base64 encoding
• MDN Web Docs — Base64 Glossary — Overview of Base64 encoding concepts and browser support
• RFC 7515 — JSON Web Signature (JWS) Base64URL — How Base64URL encoding is used in JSON Web Tokens

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