Files, Binary & Compression
Choose a file or paste text, pick an algorithm and direction, then run. Nothing leaves your browser.
Drop a file here, or choose one.
Files and text are compressed locally in your browser; nothing is uploaded.
Add a file or paste text, then choose Compress or Decompress.
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Add a file or paste text, then choose Compress or Decompress.
Pasting a config file into a chat to "just gzip it" or reaching for a command line just to check whether Brotli beats Gzip on a small payload is more setup than the task deserves. The Gzip / Deflate / Brotli Compression Tool runs all three real algorithms locally, so you can compress or decompress a file or a block of text and see exactly how many bytes you saved.
It differs from a quick script in the details that actually bite: an adjustable compression level instead of a fixed default, a byte-for-byte comparison instead of a guess, and a hard cap on how much a decompression can expand before the tool refuses to keep going.
Every run reports the original and result byte counts side by side with the percentage saved, so you can tell whether Brotli's higher quality settings were worth the extra time before you download anything.
A tiny file can decompress into gigabytes. This tool streams the output and counts bytes as they are produced, stopping the moment the total would pass 512 MiB instead of trying to hold the full result in memory first.
There is no auto-run toggle here. Brotli at its highest quality can take real time on a large input, and it needs Cancel to actually mean something — so nothing starts until you click Compress or Decompress, or press Ctrl/Cmd+Enter. Changing the algorithm, level or input marks the current result stale; run again to refresh it.
Once a result is ready, Swap previews putting that result back into the input and flipping the direction — compress then decompress, or the reverse — so you can confirm the bytes come back exactly. It only replaces your input after you click Apply, and Undo restores the previous input and result once.
Compressing text encodes it as UTF-8 first. Decompressing in text mode expects Base64 of the compressed data, because pasting raw binary as text isn't possible. The decompressed result is shown as readable text when it is valid UTF-8, and falls back to Base64 automatically when it isn't. For arbitrary binary, use File instead of Text.
Gzip and Deflate run through fflate with a 0–9 level; Brotli runs through a WebAssembly build with a 1–11 quality setting. All three execute in your browser, including in a background Worker so the page stays responsive.
Drop or choose a single file, or paste text directly. The tool doesn't build or unpack archives — it handles one raw compression stream at a time, which is what Gzip, Deflate and Brotli actually are.
Original bytes, result bytes and the percentage change are shown together after every run, including the honest case where a very small or already-compressed input comes out slightly larger.
Compression and decompression run in a Worker you can terminate mid-task. Cancel discards the in-progress run immediately instead of waiting for it to finish first.
Yes. As an online compressor and decompressor, this tool runs entirely in your browser: files and pasted text are read locally, compressed or decompressed on your device, and never sent to a server. You can check this yourself with your browser's network panel open.
Deflate is the raw algorithm inside a zlib wrapper; Gzip wraps the same algorithm with its own header and checksum, which is why Gzip files are a little larger than the equivalent Deflate output. Brotli generally compresses smaller than both, especially at higher quality settings, at the cost of being slower to compress (decompression stays fast for all three). If you need the widest compatibility, choose Gzip; if you want the smallest result and can afford the extra compression time, choose Brotli.
It trades compression time for output size: 0 stores the data with almost no compression and finishes fastest, 9 spends the most effort looking for repeated patterns and produces the smallest file, and 6 is a common balanced default. The decompressed result is identical no matter which level you pick — only the size and the time to produce it change.
A decompression bomb is a small compressed file crafted to expand into an enormous amount of data, which can freeze a tab or crash it by exhausting memory. This tool decompresses in a stream and counts output bytes as they're produced, stopping immediately once the total would exceed a fixed 512 MiB — before it ever tries to hold the full expanded result in memory.
It's safer than most alternatives because nothing is uploaded and the 512 MiB cap stops runaway expansion, and the tool verifies each format's built-in checksum so silently corrupted output isn't possible. It does not scan the decompressed content for malware, so treat the recovered bytes with the same caution you would apply to any file from an untrusted source.
Yes — select Brotli as the algorithm and use the quality slider (1–11). Quality 11 gives the smallest output but can take noticeably longer on larger files; lower values trade some compression for speed. Cancel is available at any point if a high-quality run takes longer than you'd like.
Still have a question?
Load the example to see a large, repetitive block of text shrink dramatically, or bring your own file or pasted text into the Gzip / Deflate / Brotli Compression Tool.