Free · Lossless · Browser-local
Compress CSV Files Online
Create a .csv.gz download from the original CSV bytes. Nothing is parsed, normalized, or sent to a file-processing server.
CSV → Gzip
The original bytes are compressed in this browser tab. File contents are not uploaded.
Byte-exact round trip
What the CSV compressor does
This tool uses the browser’s native gzip stream to compress the selected file as-is. Byte order marks, delimiters, quotes, encodings, and line endings remain part of the original byte sequence and return unchanged after decompression.
Inputs must be non-empty .csv files no larger than 50 MB. The download appends .gz to the complete original filename, such as report.csv.gz.
Plain answers
CSV compression questions
Does compression change my CSV?+
No. The original file bytes are passed directly into gzip without parsing or reserializing the CSV. Decompressing the result restores the exact selected bytes.
Is my CSV uploaded?+
No. Compression runs in this browser tab. Loading the page, code, or bundled sample still makes ordinary web requests.
Will gzip always make a CSV smaller?+
No. Repeated text usually compresses well, but a very small or high-entropy CSV can grow because a gzip file also contains framing data.
How do I open the .csv.gz download?+
Use a gzip-compatible archive tool or command to decompress it. The restored file keeps the original .csv filename.