About this tool
A small tool for a common chore.
ZIP files are still the simplest way to hand a group of files to someone else. The YunoNext ZIP Compressor makes that job local, direct, and honest about the result.
The reason
The file does not need to travel to be compressed.
Most online ZIP tools ask you to upload files, wait for a server, and download the result. For a folder of private documents, that is an unnecessary detour. Browsers already have permission to read the files you select and enough compute to deflate them.
This tool uses that capability directly. The files stay in the tab, a Web Worker handles the compression, and the download is created from memory. The host serves the page; it never receives the archive.
That choice also sets the boundaries. A browser tab has finite memory, so the tool refuses jobs that are too large instead of risking a crash. It cannot open password-protected archives because the browser-side library does not support them. And it will tell you when a rebuild is larger instead of pretending every file benefits from compression.
What it does
One job, done carefully.
- Creates a standard ZIP from files or a folder, with relative paths intact.
- Rebuilds an existing ZIP at any level from Low (1) to Max (9).
- Validates entries while loading and reports the actual before/after byte count.
- Lets you cancel a running job without producing a partial download.
What it does not do
No hidden server, no fake savings.
- It does not upload, store, or scan your files for malware.
- It does not create or remove passwords, split archives, or produce RAR/7z files.
- It does not promise that already-compressed media will get smaller.
- It does not keep your files between visits. Reloading the page clears them.
How it is built
A small stack with visible boundaries.
The tool is part of the YunoNext site. It uses the File API, a module Web Worker, and JSZip to build the archive. The result is turned into a Blob URL in the page, so the download never needs a server round trip.
File API
Selected files and folder entries are read only after you choose them.
Web Worker + JSZip
Compression runs off the main thread so the page stays responsive.
Local Blob
The finished archive becomes a download link created inside the browser.
A note on third-party code
JSZip is bundled with the site rather than loaded from a CDN. The browser downloads the page's own JavaScript, CSS, and fonts; it does not send file data to an external service.
Principles
The result should be believable.
These are the choices that shape the tool, even when a simpler marketing claim would be easier.
Show the bytes
Savings are calculated from the actual input and output sizes. A small archive may grow, and the result says so.
Keep the original in reach
When compression does not help, the original ZIP stays as the primary download instead of being replaced by a larger rebuild.
Refuse rather than freeze
The file and entry limits are there to protect the tab. An honest limit is better than a browser crash halfway through.
Try it
Put it to work on a real folder.
The compressor is free, needs no account, and runs in the page you already have open.