ZLib Decompress Online

Decompress zlib-encoded data instantly. Paste Base64-encoded zlib content or upload a compressed file to get the original text.

Compressed Input

Upload File

Decompressed Output

Decompressed output will appear here

About ZLib:

• Uses DEFLATE compression algorithm
• Common in PNG images and HTTP compression
• Simpler header than gzip format
• All processing happens in your browser

Instant ZLib Decompression

Decompress zlib-encoded data directly in your browser. Works with Base64-encoded strings or raw compressed files. All processing happens locally, ensuring your data remains private and secure.

ZLib Decoder

How this ZLib Decompress Online works

This decompression tool processes zlib-formatted data using the DEFLATE algorithm implementation from the pako library. Unlike gzip, zlib uses a simpler header structure with just a compression method byte and flags, making it more suitable for embedded data streams. The tool accepts Base64-encoded zlib data or raw compressed file uploads.

The decoder validates the zlib header checksum (Adler-32) before inflating the compressed stream through Huffman tree reconstruction and sliding window dictionary processing. The tool handles all standard compression levels and window sizes specified in RFC 1950. Invalid or corrupted data triggers clear error messages indicating the failure point.

Processing happens entirely within your browser, eliminating data transmission concerns for sensitive compressed content. Common use cases include debugging PNG image data chunks, extracting embedded zlib streams from PDF files, and processing HTTP compressed responses for API development and testing workflows.

How to Use

Input compressed data

Paste Base64-encoded zlib data or upload a compressed file.

Automatic decompression

The tool instantly decompresses your data using the DEFLATE algorithm.

Get your output

Copy the decompressed text or download it as a file.

Example Usage

A simple Base64-encoded zlib string decompressed to plain text.

Input

eJwrSS0u0c1IzcnJBwALywME

Output

test data

Frequently Asked Questions

What is ZLib compression?

ZLib is a software library and data format used for data compression. It uses the DEFLATE algorithm and adds a small header and checksum, making it slightly different from raw DEFLATE or gzip.

What's the difference between Gzip and ZLib?

Both use DEFLATE compression, but they have different headers and checksums. Gzip includes file metadata like filename and timestamp, while ZLib has a simpler structure focused on data streams.

What formats does this tool accept?

You can paste Base64-encoded zlib data directly, or upload a raw compressed file. The tool automatically decompresses the zlib-formatted data.

Is my data secure?

Yes, all decompression happens locally in your browser. Your data is never uploaded to any server, ensuring complete privacy and security.

What if decompression fails?

Ensure your input is valid zlib-compressed data. If the data was compressed with gzip, use our Gzip Decompress tool instead. ZLib and Gzip are similar but not interchangeable.

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The ZLib Decompress Online is maintained by CodeItBro. We aim to provide the best free developer tools on the web. If you have feedback or suggestions, please visit our contact page.

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