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LZ77 Compressor

Compression · Free Online Tool

LZ77 sliding window compress/decompress for learning.

By EZ4Code TeamLast updated: 2026-10-29

Implementation note：Educational implementation. This is a compact, readable version intended to illustrate how the algorithm works. Its output is not byte-compatible with standard implementations, so do not use it to compress or decompress real data.

Input Text209 chars

LZ77 Tokens (JSON)

0 chars

Click "Compress" to run...

Sliding Window

Searches a 4 KB window for matches up to 18 bytes — the textbook LZ77 scheme.

Inspectable Output

Emits literal/match tokens as JSON so you can see exactly how the data was encoded.

Educational

Great for learning how deflate and LZ4 build on the LZ77 idea.

How to Use LZ77 Compressor

1Enter or paste the text you want to compress.
2Select the compression algorithm (gzip, deflate, or brotli).
3Click compress to reduce the data size.
4Copy or download the compressed output.

Features

✓100% free — no signup, no subscription, no ads
✓Runs entirely in your browser — data never leaves your device
✓Fast and lightweight — instant results
✓Cross-platform — works on desktop, tablet, and mobile

Frequently Asked Questions

What compression algorithms are supported?

We support gzip, deflate, and brotli compression algorithms for text data.

Is there a file size limit?

Since tools run in your browser, the limit depends on your device memory. Most tools handle several megabytes without issues.

Can I decompress data produced by other software?

Yes. The decompression tools accept standard gzip, deflate, and brotli streams from any compliant source — command-line tools, web servers, or other libraries.

Why does the compressed output look unreadable?

Compressed data is binary, not text. Use Copy as Base64 or download it as a file — pasting raw compressed bytes into a text field will show garbled characters.