How do I zip files online for free?
Drag your files or a folder into the box above, keep Zip Files selected and press Create ZIP. Your browser packs everything into one .zip on your own device, then you press Download ZIP. It is free, needs no account or login, and your files are never uploaded.
What does this tool do?
Okviro Tools Zip & Compress is a free online file compressor and ZIP maker that runs entirely in your web browser. It has two modes:
- Zip Files packs many files, or whole folders with their subfolders, into a single .zip archive of up to 500 MB. Use it to email or upload a bundle of documents, share a project, or back up a folder.
- Compress Files makes each file smaller. Photos are re-encoded as WebP or JPG with the quality and size you choose. JSON, CSV, TXT, XML and code files are compressed with DEFLATE (level 9) into .zip or .gz, and JSON can be minified first.
The work is done by a background Web Worker, so the page stays responsive even with hundreds of megabytes, and a progress bar shows how far it has got. When it finishes you see exactly how much space you saved, for example "Reduced from 400 MB to 15 MB".
How to zip a folder or several files
- Drag your files or a whole folder into the box, or click Choose files. They stay on your device.
- Keep the Zip Files tab selected and type a name for the archive. Text and table files get level 9 compression automatically; archives, photos and other binary files are stored as-is.
- Press Create ZIP and watch the progress bar. Your browser packs the files in the background.
- Press Download ZIP. The report shows the original and the new size, for example 400 MB to 120 MB.
Which files are compressed and which are stored?
Before packing, the tool checks each file's extension and its first 512 bytes, in parallel, so a renamed archive is still recognised:
| Files | Inside the ZIP |
|---|---|
| CSV, JSON, TXT, LOG, XML, HTML, code | Maximum compression (DEFLATE level 9) |
| ZIP, RAR, 7Z, TAR, GZ | Stored as-is, never compressed twice |
| XLSX, DOCX, PPTX, PDF | Stored as-is (they are already compressed inside) |
| JPG, PNG, WebP, MP4, MP3, other binary files | Stored as-is, in their original folder |
Every file ends up in exactly the folder and subfolder it came from, for example project/data/users.csv. Empty folders you drag in are kept too.
How to compress photos, JSON, CSV and text files
- Add the files, then switch to the Compress Files tab.
- For photos, pick WebP (smallest) or JPG (accepted everywhere), a quality between 40 and 95, and optionally a maximum size such as 1920 px.
- For text and data files, pick .zip or .gz and leave "Minify JSON" on for the smallest result.
- Press Compress and download each file, or all of them together in one ZIP.
How much smaller will my files get?
| File type | Typical saving | Best option |
|---|---|---|
| JSON, CSV, TXT, logs | 70–90% | Compress Files, .zip or .gz |
| HTML, CSS, JS, XML, SVG | 60–85% | Compress Files or Zip Files |
| Phone photos (JPG, HEIC) | 50–80% as WebP, more with 1920 px | Compress Files, WebP |
| PNG screenshots | 60–90% as WebP | Compress Files, WebP |
| PDF, DOCX, XLSX | 0–15% | Zip Files, to bundle them |
| Videos, MP3, ZIP | about 0% | Zip Files, to bundle them |
Savings depend on the content. Text with lots of repetition shrinks the most; files that are already compressed hardly shrink at all, which is normal and not a fault of the tool.
Why use this instead of other online ZIP tools?
- Free, with no login. No account, no email, no watermark, no daily limit and no "premium" upsell.
- No upload: files stay on your device. Most online compressors send your files to their server. Here your browser does the work, so contracts, photos and customer data never leave your device.
- Faster for big files. There is no upload or download wait: a 300 MB folder is zipped at the speed of your own computer, not your internet connection.
- One page for both jobs. Bundle files into a ZIP or shrink them, without installing WinZip, WinRAR or 7-Zip.
How do I reduce file size online?
It depends on the file. Photos shrink the most when they are re-encoded: use the Compress Files tab to turn them into WebP or JPG at a lower quality or size. Text, tables and data files such as JSON, CSV and logs shrink by 70–90% when packed into a ZIP or GZIP. Files that are already compressed, like MP4 videos, MP3s, PDFs and existing ZIPs, barely get smaller in any file compressor.
How do I create a ZIP file without WinRAR or 7-Zip?
Drop your files or a folder into the box, keep Zip Files selected and press Create ZIP. This zip online tool builds the archive in your browser, so you don't need to install WinRAR, 7-Zip or WinZip, and it works the same on Windows, Mac, Chromebook, Android and iPhone. The ZIP opens with a double-click on any computer.
Questions
Is this ZIP tool really free?
Yes. It is completely free, with no sign-up, no login, no watermark and no daily limit. There is no paid version.
Are my files uploaded to a server?
No. Zipping and compression run inside your browser on your own device. Your files are never sent to Okviro Tools or anyone else. The page only downloads the open-source JSZip and FileSaver.js code from jsDelivr.
How big can the files be?
Each file can be up to 500 MB, and all files together up to 500 MB per ZIP. A larger file is marked in red with a clear error and nothing is processed until you remove it. On phones and older computers with little memory, batches under 200 MB are more reliable.
What happens if two files have the same name?
The second file is renamed automatically, for example data.csv becomes data (1).csv, so nothing is overwritten inside the ZIP. If you add the exact same file twice, the copy is skipped.
Are ZIP, RAR or 7z files compressed again?
No. Archives (ZIP, RAR, 7Z, TAR, GZ), Office files such as XLSX, photos, videos and other binary files are recognised by their extension and their first bytes and stored as-is. Compressing them again would only cost time. CSV, JSON, TXT, LOG and XML files get maximum compression, level 9.
Can I zip a whole folder?
Yes. Drag the folder into the box or click Choose folder. Subfolders are kept inside the ZIP exactly as they are on your computer.
Why is my ZIP barely smaller than the original files?
Photos, videos, music, PDFs and Office files are already compressed, so zipping them saves little. Text files such as JSON, CSV and TXT usually shrink by 70 to 90 percent. To make photos smaller, use the Compress Files tab, which re-encodes them as WebP or JPG.
How much smaller do photos get?
A phone photo saved as WebP at quality 80 is often 50 to 80 percent smaller, and limiting the longest side to 1920 pixels saves even more. The page shows the exact before and after size for every photo.
Does it work on iPhone and Android?
Yes. Open the page in Safari or Chrome, tap the box and pick files. Folder selection works on computers; on phones choose the files themselves. Safari cannot create WebP images, so on iPhone photos are saved as JPG.
How do I open a .zip or .gz file?
Windows and macOS open ZIP files with a double-click. GZIP (.gz) files open with 7-Zip on Windows, the built-in Archive Utility on macOS, or gunzip on Linux. Choose ZIP if you are not sure.
Is this file compressor safe for private documents?
Yes. Unlike most online file compressors, nothing is uploaded: your browser reads and packs the files on your own device, so contracts, ID scans and customer data never leave it.