7-Zip Compressor
Compress files to 7z format using real 7-Zip in your browser — no installation, no upload, completely private.
Drop files here or click to browse
Select files to compress into a 7z archive
How to Compress Files to 7z
- 1Click Add Files or drag and drop any files you want to compress into the tool.
- 2The tool packs your files into a single .7z archive using the LZMA2 algorithm — entirely inside your browser with no upload.
- 3Click Download to save the compressed archive to your device. Your original files are untouched.
7z vs ZIP — Which Compression Format Should You Use?
ZIP is the most universally compatible archive format — it opens natively on Windows, macOS, and Linux without any extra software. 7z typically achieves significantly better compression (often 30–70% smaller than ZIP for the same files), but requires 7-Zip or compatible software to open. For sharing with non-technical recipients, ZIP is the safer choice. For archiving your own files, compressing developer assets, or sending to people who already have 7-Zip, the 7z format wins on efficiency.
Common Uses for 7z Compression
Archiving Projects
Pack an entire project folder — source code, assets, configs — into a single portable archive with maximum compression before long-term storage or handoff.
Email Attachments
Email providers limit attachment size (usually 25 MB). Compressing files to 7z often reduces total size enough to stay under the limit without a file-sharing service.
Log File Archives
Log files are highly repetitive text — ideal for 7z compression. A 500 MB log directory often compresses to under 20 MB, saving significant storage or transfer costs.
Deployment Packages
Bundle static builds, configuration files, or deployment assets into a single lightweight archive for transfer to a server or CI/CD pipeline.
Point-in-Time Backups
Before a major refactor or system change, compress the current state into a .7z archive as a lightweight snapshot — no full version control system needed.
Sharing Multiple Files
Instead of sending many files one by one, combine them into a single .7z archive. Recipients extract everything at once with a single action.
Frequently Asked Questions
What is 7z format and why use it instead of ZIP?
7z is a compressed archive format introduced by the 7-Zip project. It uses the LZMA2 compression algorithm, which typically achieves 30–70% better compression ratios than ZIP for the same files. The trade-off is that 7z is less universally supported than ZIP — recipients need 7-Zip or compatible software to open the archive. Use 7z when file size is the priority and your recipients are comfortable with it; stick with ZIP for maximum compatibility.
How much compression can I expect?
Compression ratio depends heavily on file type. Plain text, log files, and source code often compress by 70–90%. Office documents (Word, Excel) typically compress by 50–80%. Already-compressed formats like JPEG images, MP3 audio, and existing ZIP files gain very little (0–5%) because the data is already compact. This tool uses maximum LZMA2 compression by default.
Is the compression lossless — will my files be identical after extraction?
Yes. 7-Zip compression is always lossless. Every byte of every file is perfectly preserved in the archive. When you extract the archive later, files are bit-for-bit identical to the originals. Nothing is changed, approximated, or removed.
Are my files uploaded to a server?
No. This tool runs entirely in your browser using WebAssembly — the real 7-Zip engine compiled to run locally. Your files are processed in browser memory and never transmitted to any server. There is no upload, no server-side processing, and no data retention of any kind.
Can I compress multiple files at once?
Yes. Add as many files as you need and they will all be packed into a single .7z archive. The archive preserves the original file names. There is no limit on the number of files, only the total size relative to your device's available memory.
What is the maximum file size I can compress?
The practical limit is your browser's available memory. On a modern desktop with 8 GB RAM, archives up to several hundred megabytes work reliably. Very large files (1 GB+) may cause the browser tab to run out of memory. For those, use the desktop 7-Zip application instead.