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zLib Decompress Online

Decode zLib or deflate-compressed data from Base64, hex, or binary-string form and inspect the decompressed text locally.

Last updated: May 28, 2026

Client-Side Processing
Input Data Stays on Device
Instant Local Execution

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What is zLib Decompress Online?

zLib is a compressed data format often used inside application protocols, caches, databases, and server-side compression libraries. It wraps deflate-compressed bytes with metadata and a checksum. This tool inflates zLib data into UTF-8 text and also attempts raw deflate where the browser supports it.

How to Use zLib Decompress Online

1

Paste your zLib or deflate payload into the input area.

2

Select Base64, hex, or binary string for the input encoding.

3

Click Decompress to inflate the bytes.

4

Review the decoded output and byte counts.

5

Copy or download the result for debugging or documentation.

Common Use Cases

  • Inspecting compressed cache values from application logs.
  • Decoding Base64 zLib strings from integration payloads.
  • Debugging deflate output from a backend service.
  • Checking whether a payload is zlib-wrapped or GZip-wrapped.
  • Reviewing compressed text without installing a local inflate utility.

Example Input and Output

A Base64 zLib sample expands to readable UTF-8 text.

zLib Base64 input
eJwFwUEOgCAMBMCv7At4h0cPJJ5B1kjSUtJq1N87s1DEcLgpNtZsJrFKGbwS8tkDu+l0RrAhik4h+M4yWqAPfHY7qtsT9PQDBZ0bpA==
Decompressed text
Hello from WebToolsPlanet. This compressed sample expands in your browser.

Privacy note

Decompression happens client-side. Sensitive compressed logs or test payloads are not transmitted.

Workflow tip

zLib Base64 often starts with eJ for small text payloads, while GZip Base64 often starts with H4sI.

Frequently Asked Questions

What is the difference between zLib and GZip?
Both commonly use deflate compression, but GZip and zLib have different wrappers. If one tool fails, try the other format.
Can this decode raw deflate?
The tool first tries zlib-wrapped deflate and then raw deflate when the browser supports that decompression format.
Does this upload my compressed data?
No. It uses browser decompression APIs, so the input and output stay on your device.
Why does my output look garbled?
The decompressed bytes may not be UTF-8 text. This page is intended for compressed text payloads.

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