Base64 Encoder / Decoder – Encode & Decode Online
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Calcon's free Base64 Encoder/Decoder converts text or files to Base64 and back instantly. Supports Unicode input, URL-safe Base64, and file uploads. All processing happens in your browser — nothing is sent to a server.
Base64 Character Set
| Characters | Count | URL-safe |
|---|---|---|
| A–Z | 26 | Same |
| a–z | 26 | Same |
| 0–9 | 10 | Same |
| + | 1 | - |
| / | 1 | _ |
| = (padding) | — | Omitted |
Frequently Asked Questions
What is Base64 encoding?
Base64 encodes binary data as printable ASCII text using 64 safe characters. It is used to embed images in HTML, send binary data in JSON APIs, and encode email attachments. Every 3 bytes of input become 4 Base64 characters, increasing size by ~33%.
What is URL-safe Base64?
Standard Base64 uses + and / which conflict with URL syntax. URL-safe Base64 replaces them with - and _, making the result safe for use in URLs, query strings, and filenames without percent-encoding.
Does Base64 compress data?
No — Base64 expands data by approximately 33%. It is an encoding scheme, not compression. For compression, use gzip or Brotli before encoding. Base64's purpose is safe transmission, not size reduction.
What are common uses of Base64?
Common uses: embedding images as data URIs in CSS or HTML, encoding binary payloads in JSON APIs, encoding credentials in HTTP Basic Auth headers, MIME email attachments, and storing binary data in text-only systems.
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