ZIP Builder
Bundles arbitrary files into one ZIP archive directly in the browser. Files are compressed with deflate (level 6) using the in-page `fflate` library, so nothing is uploaded and the work scales with your machine. Useful when you need to send a few attachments at once but the original tools are on your phone or a locked-down machine.
No files yet — drop or pick a few.
Everything runs in your browser — files never leave your device.
How to use
- Drop files into the upload area, or click to pick them.
- Set the output filename (defaults to `archive.zip`).
- Hit Build, then Download. The size of the archive and the compression ratio are shown after building.
Frequently asked questions
- Are the files uploaded anywhere?
- No. The bundling runs in your browser tab — the files are read, compressed, and offered as a download all locally. Closing the tab discards everything.
- What's the size limit?
- There's no hard cap, but the whole archive is held in memory at once. For mobile that's typically fine up to a few hundred MB; for very large bundles use a desktop tool that streams.
- What about duplicate filenames?
- When two dropped files would share a name inside the archive, the second one becomes `name (2).ext`, the third `name (3).ext`, and so on — same behaviour as macOS Finder and Windows Explorer copy-paste.
- What compression level is used?
- Deflate level 6, the default for most archivers. Higher levels save little extra and would noticeably slow down a phone.
Related tools
ZIP Inspector
Drop a ZIP and see every file inside — sizes, contents, and per-file download — without unpacking it locally.
PDF Merger
Drop two or more PDFs, reorder them with the arrow buttons, and download a single merged PDF — all in your browser, no upload.
PDF Compressor
Shrink a PDF by re-encoding the images inside it. Text stays selectable and searchable. Nothing is uploaded.
Audio Trimmer
Cut a clip out of an audio file by dragging across its waveform, add fades, and download it as a WAV. Nothing is uploaded.
Add Page Numbers to a PDF
Number the pages of a PDF — position, style, starting number and whether to skip the cover — and download it. Nothing is uploaded.
Add a Watermark to a PDF
Stamp text like DRAFT or CONFIDENTIAL across a PDF — size, colour, opacity and angle you choose — and download it. Nothing is uploaded.