Do I need the "begin" and "end" lines?

No. The decoder accepts raw encoded data lines without the header and footer. If a "begin" line is present, the filename and mode are extracted and shown; if not, default values are used.

What if my encoded text has extra blank lines or spaces?

The decoder skips blank lines and ignores the "begin", backtick (end-of-data), and "end" marker lines automatically. Stray whitespace at the end of lines is also trimmed.

Can this tool decode binary files?

Yes. The decoded bytes are reconstructed in full. Text content is shown in the output area, and a "Download File" button lets you save the exact binary output to disk.

Why does my output contain garbage characters?

If the original file was binary (an image, executable, etc.), the raw bytes will not display as readable text. Use the "Download File" button instead of reading the text area.

How does UUdecoding work?

Each encoded line starts with a length character (byte count + 32). The remaining characters encode 6-bit groups that are reassembled into the original 8-bit bytes, four encoded characters per three original bytes.

Is this compatible with the Unix uudecode command?

Yes. The tool follows the standard UUdecode algorithm accepted by Linux and macOS uudecode utilities, including the backtick-as-zero-byte convention used by modern encoders.

Uudecode Decoder

Name: Uudecode Decoder
Availability: InStock
Author: Nham Vu

Paste a UUencoded block and instantly recover the original text or binary content in your browser.

UUencoded Input

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Decoded Output

Decoded content will appear here

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Summary

Paste a UUencoded block and instantly recover the original text or binary content in your browser.

How it works

Paste your UUencoded text into the input field (include the "begin" header and "end" footer if present).
Click "Decode" to run the decoding algorithm client-side in your browser.
Each encoded line is parsed: the first character gives the byte count, and the remaining characters are converted back to 6-bit groups.
The recovered bytes are assembled and displayed as decoded text.
If the original data was binary, click "Download File" to save the exact binary output.
Filename and permission mode shown in the "begin" line are extracted and displayed automatically.

Use cases

Recover the original content from legacy email attachments using UUencoding.
Decode UUencoded Usenet binary posts archived from the early internet.
Verify that your UUencoder produces output that round-trips correctly.
Debug shell scripts that use uuencode/uudecode to embed binary payloads.
Inspect UUencoded configuration blobs embedded in older Unix tools.
Learn the UUencoding algorithm by comparing encoded input with decoded output.

Frequently Asked Questions

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Last updated: 2026-05-23 · Reviewed by Nham Vu