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ConvertBox

Base64 Encoder/Decoder

Encode text to Base64 or decode it back to plain text. Free in-browser tool — handles UTF-8 (CJK, emoji) and Base64URL (JWT), all on your machine.

?What is Base64?

Base64 is a binary-to-text encoding scheme that represents binary data in an ASCII string format. It is commonly used when there is a need to encode binary data that needs to be stored and transferred over media that are designed to deal with text.

  • 1Email attachment transfer
  • 2Embedding images in HTML/CSS
  • 3Basic HTTP Authentication
  • 4URL-safe data transmission
  • 5Binary storage in databases
  • 6Intermediate step in encryption

How to Use

  1. Choose "Encode" or "Decode" mode
  2. Paste the text you want to process — UTF-8 multibyte characters (CJK, emoji, accents) are handled correctly
  3. The result appears in the right panel; copy with one click and use it in Postman, curl, Slack, or a Jira ticket
  4. For Basic auth headers: encode `username:password` and use as `Authorization: Basic '<Base64>'`
  5. For JWT debugging: paste the middle segment (payload) and decode to inspect the sub, exp, and iat claims without installing tools
  6. Everything runs in your browser — credentials, tokens, and API keys never leave your machine

All processing is done in your browser, and files are never sent to a server.

Frequently Asked Questions

Base64 is used to encode binary data into ASCII text, commonly for email attachments, embedding images in HTML/CSS, and data URLs.
No, Base64 is an encoding scheme, not encryption. It does not provide any security or data protection.
This tool encodes text to Base64. For binary file encoding, you would need a file-specific Base64 encoder.
No. Base64 is reversible encoding, not encryption. Anyone can decode it instantly — never use it to hide secrets.
Yes. Text is UTF-8 encoded before Base64, so Japanese, Chinese, Korean, Spanish accents, and emoji round-trip cleanly.
No. Encoding and decoding happen locally in your browser — safe for API keys, tokens, or any sensitive payload.
Yes. Toggle the URL-safe option to swap "+" "/" "=" for "-" "_" and no padding — required by JWT and many web APIs.
No. All operations are processed entirely inside your browser's local sandbox using client-side APIs (like WebAssembly, pdf-lib, or HTML5 Canvas). Your files and data never leave your device.
The tool is completely free with no usage limits. However, since processing occurs in your browser's memory, we recommend keeping file sizes under 50MB (especially for heavy files like PDFs or videos) to ensure stability.
No. All tools on ConvertBox are 100% free. We do not insert watermarks, limit features, or require any registration or payment.
Yes. Once the page and its local library dependencies are loaded in your browser, the conversion logic runs completely offline without needing an active internet connection.

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