Gzip Compression Test

Test how well your text or Base64 strings compress with gzip. See compression ratios, size comparisons, and verify data integrity — all in your browser.

Last Updated: August 2026
100% Client-Side — Your data never leaves your device

Enter text or a Base64 string to test how well it compresses with gzip

Why this tool is safe

Your data never leaves your device — everything runs in your browser.

No server uploads. Other tools send your files to their servers. Ours don't.
Zero tracking of content. We never see, store, or log anything you convert.
Works offline. Once loaded, the tool works without an internet connection.

Gzip Compression in Code

Compress and decompress data with gzip in your language.

Python
import gzip
import base64

# Compress text with gzip and encode as Base64
text = "Hello, World! " * 100
compressed = gzip.compress(text.encode("utf-8"))
b64 = base64.b64encode(compressed).decode()
print(f"Original: {len(text)} bytes, Compressed: {len(compressed)} bytes")
print(f"Ratio: {len(compressed) / len(text):.1%}")

# Decompress from Base64-encoded gzip
decoded = base64.b64decode(b64)
decompressed = gzip.decompress(decoded).decode("utf-8")
assert decompressed == text  # Data integrity check

# Compress a file
with open("data.json", "rb") as f:
    compressed = gzip.compress(f.read())
with open("data.json.gz", "wb") as f:
    f.write(compressed)

Frequently Asked Questions

Search below or browse through our most commonly asked questions.

Paste your text, JSON, or Base64 string into the input area, and the tool uses your browser's built-in Compression Streams API to gzip it. You'll see the original size, compressed size, and the compression ratio — all computed locally without any data leaving your device.
Base64 strings are already about 33% larger than the original binary data. Compressing them with gzip can often recover that overhead, especially for repetitive or textual content. This tool helps you decide whether enabling gzip on your API or web server is worth the effort.
It depends entirely on the content. Highly repetitive text can compress by 80-90%, while random or already-compressed data (like JPEG images or encrypted content) may barely shrink at all. The tool shows you the exact ratio so you can make an informed decision.
Generally no — and it can actually make things slightly larger due to gzip's header overhead. If you're testing data that's already compressed (like PNG images or ZIP files encoded as Base64), expect little to no additional compression. The tool will show you the honest result either way.
Yes, gzip is completely lossless. When you decompress the data, you get back exactly what you put in. The tool verifies this by decompressing the gzipped output and comparing it to the original input.