Base64 Encoder & Decoder
Encode or decode Base64 for data URLs, MIME attachments, and embedded blobs in JSON. Remember: Base64 is encoding, not encryption—anyone can reverse it.
File upload and download help you round-trip small binaries without a local CLI.
How to use
- Encode: Enter text and click Encode to Base64, or use "Choose file" to encode a file.
- Decode: Paste a Base64 string and click Decode to text, or Download as file for binary data.
- Use Share URL to create a link with your data (
?data=for text,?encoded=for Base64). - Use Copy to copy the result to the clipboard.
1What Base64 is actually doing
Base64 represents binary data using a small alphabet of letters, digits, and a couple of symbols so it can travel through systems that only handle text safely.
You will see it in data URLs, email MIME parts, certain authentication headers, and when APIs embed small images or certificates as strings.
- Encoding is not encryption: anyone can decode Base64, so never treat it as a way to hide sensitive information.
- URL-safe variants swap characters like + and / so values fit cleanly inside query strings and path segments.
2Practical workflows
Developers often decode a chunk from a log line to confirm it matches the original file, or encode a small binary blob to paste into a test harness.
When you work with files, prefer verifying the byte size and a checksum after round-tripping encode and decode to ensure nothing was corrupted in transit.
3Tips for fewer mistakes
Strip whitespace and line breaks from pasted strings if a decode fails—some copy sources add hidden characters.
If you are embedding in JSON, remember that JSON strings need escaping; decoding the inner Base64 first can make nested structures easier to read.
4Where Base64 appears in real systems
Email attachments use MIME encoding. JWT segments are Base64url. Some databases store small binaries as text columns. Data URLs embed images directly in HTML or CSS for icons and thumbnails.
When debugging, developers often copy a Base64 chunk from a log, decode it locally, and compare the result to the expected file hash.
5Padding, line breaks, and URL-safe variants
Standard Base64 may end with one or two `=` padding characters. URL-safe variants replace `+` and `/` so values survive query strings without extra escaping.
Pasted strings from PDFs or chat apps sometimes include line breaks every 76 characters; strip whitespace if decode fails unexpectedly.
6Quick checklist for Base64 workflows
Confirm whether padding characters are required for your target system. After decoding binary output, compare file size and a hash against the source when integrity matters.
- Remember encoding is not encryption.
- Strip line breaks from pasted strings if decode fails unexpectedly.
Examples
Encode plain text
The string "Hello" encodes to the value below (standard alphabet).
SGVsbG8=Decode to inspect
Paste an encoded header value from a log to see the underlying JSON or binary metadata.
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9