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Paste the Base64- or hex-encoded GZIP payload you want to decompress.

For .gz files (e.g. archives, log files) use the file upload form below.
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Output

text
Compressed (bytes): 0 · Decompressed (bytes): 0 · Ratio: —
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Decompress .gz files

Select a .gz file to upload and decompress.

Drag & Drop file here or click to select

Decompressing gzip blobs is part of debugging life on US and UK developer teams: pulling apart an AWS S3 `Content-Encoding: gzip` object that came out of CloudFront, inspecting a Sentry minidump uploaded gzipped, or unwrapping the RFC 1952 stream nested inside an HTTP archive (HAR) file exported from Chrome DevTools. UK public-sector engineers analysing API response bodies dumped by the GOV.UK Performance Platform reach for the same operation. This decompressor runs entirely client-side through the browser DecompressionStream API, so the file or hex string you paste in never crosses a network boundary and stays out of any third-party audit trail.

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What is GZIP decompression?

GZIP is a lossless compression file format defined by RFC 1952. Decompression reverses the DEFLATE algorithm (RFC 1951) — reading back the LZ77 references and Huffman-coded symbols to reconstruct the original bytes exactly.

How does GZIP decompression work?

Your input is processed entirely in your browser using the native DecompressionStream('gzip') API. The high-level steps are:

  1. The tool parses your input as either Base64 or hex (for text) or reads the raw bytes of the .gz file you upload.
  2. The 10-byte gzip header is validated, the DEFLATE payload is identified, and the 8-byte footer (CRC32 + original-length-mod-2^32) is set aside for verification.
  3. Bytes are fed through a DecompressionStream configured for the gzip format.
  4. The browser reverses DEFLATE: Huffman codes are decoded back to symbols and LZ77 back-references are expanded into the original byte stream.
  5. The stream verifies the CRC32 and length footer against the recovered bytes, then emits them as UTF-8 text in the text form or as a downloadable file in the upload form.

Why decompress with this tool?

  • Inspect responses: read GZIP-encoded HTTP bodies and CDN payloads that other tools would render as binary noise.
  • Recover archives: extract .gz log files, configuration dumps, and tarball components without installing extra software.
  • Privacy: decompression happens entirely in your browser. The input never reaches our servers.
  • Standards-compliant: accepts any RFC 1952 stream produced by the gzip CLI, by HTTP servers, or by language standard libraries in Python, Node.js, Go, Java, or Rust.

What are common applications of GZIP decompression?

Decompressing GZIP shows up across web work and tooling:

  • Debugging APIs: pasting a raw Content-Encoding: gzip response body to see the underlying JSON or HTML.
  • Log forensics: opening rotated .log.gz files to grep for events without a full extraction pipeline.
  • Verifying backups: confirming that a .gz archive produced by another tool decompresses cleanly before relying on it.

What does a GZIP decompression example look like?

A 200 byte Base64 string starting with H4sI is the canonical sign of a gzip header — the magic bytes 1f 8b encode to those characters. Pasting that string and pressing DECOMPRESS reproduces the original text exactly, byte for byte, including whitespace and trailing newlines.

This GZIP decompressor accepts any RFC 1952 input and produces the original bytes directly in your browser. Pair it with the GZIP Compressor to round-trip text or files without ever leaving the page.