CSV Decompressor
Upload a compressed file, either a standard .csv.gz/.gz export or a headerless raw DEFLATE stream, and this tool detects the format and decompresses it back to plain text in your browser. Copy or download the plain CSV; you'll get a clear error message if the file isn't a valid gzip or deflate stream.
Reviewed by Vincenzo Manto, Founder & Lead Developer · Last updated September 27, 2026
How it works
- 1
Upload or drag in the compressed file (.gz, .csv.gz, or .deflate).
- 2
The tool tries gzip/zlib decoding first, then falls back to raw DEFLATE.
- 3
The plain-text result appears instantly, with the detected format shown.
- 4
Copy the text or download it as a .csv file.
Two decompression formats, one tool
Most .gz files use the standard gzip container, but some systems produce raw DEFLATE streams without the gzip header, for example certain HTTP responses or custom export pipelines. Rather than making you guess which one you have, this tool tries gzip decoding first and falls back to raw DEFLATE if that fails, so you get a working result either way.
Clear feedback when something is wrong
Corrupted downloads, truncated files, or files that were never actually compressed are common sources of frustration. Instead of a cryptic crash, this tool surfaces a plain-English error explaining that the uploaded file doesn't look like valid gzip or deflate data, so you know immediately whether the problem is the file itself.
Frequently asked questions
What's the difference between this and the Gzip CSV Reader?
The Gzip CSV Reader assumes gzip input and shows a parsed table preview. This decompressor is more general: it handles both standard gzip/zlib streams and headerless raw DEFLATE data, and focuses on returning clean plain text rather than a table.
What happens if I upload a file that isn't compressed data?
Both the gzip and raw-deflate decoders will fail, and the tool shows a clear error message explaining that the file doesn't look like valid gzip or deflate data.
Does this work for compressed files that aren't CSV?
Yes, it decompresses any gzip or deflate stream to text. It's framed around CSV since that's the most common use case for this kind of export, but the decompression itself doesn't care about the format inside.
Is any part of this processed on a server?
No. Decompression runs with the pako library in your browser tab, and the file stays on your device.
Why would a CSV export use raw deflate instead of gzip?
Some APIs and storage systems strip the gzip header/footer to save a few bytes, producing a raw DEFLATE stream. This tool automatically falls back to that mode when standard gzip decoding fails.