Dummy ZIP File Generator
Every dummy ZIP file is a standard archive that passes unzip -t and 7-Zip, from 1 KB to 1 GB.
Sample ZIP files, ready to download:
One click, exact size (1 KB = 1,024 bytes), default options, built in your browser.
A dummy ZIP file is a standard ZIP archive made for testing, and it passes unzip -t and 7-Zip. Download one free at the exact size you need, from 1 KB to 1 GB. It is built in your browser, so you can test uploads, extraction, virus scanning and download speeds without sharing real files.
How we check it: every generated file must be exactly the size you set and pass our own structure and CRC-32 checker, JSZip, Info-ZIP unzip -t and 7-Zip 24.09; the last run on 21 October 2026 passed 155 of 155 runs across 17 formats (how the files are made and checked).
Download a dummy ZIP file by size
Each page below has a ready-made ZIP test file, its exact byte count and the limits it is closest to.
What is inside a dummy ZIP file
The generated archive has a small, predictable structure, so you know exactly what your code will see when it opens it (how we build and check these files):
- Three entries: README.txt (what the file is), sample_manifest.json (a small JSON object with the name, creation time and target size) and archive_payload.dat.
- archive_payload.dat holds zero bytes and carries almost all of the size, so a 100 MB ZIP extracts to roughly 100 MB of data.
- Entries are stored without compression. The size on disk is exactly the number of bytes you asked for, and extraction is fast.
- A standard central directory and end-of-central-directory record, so tools that read the index first, such as unzip and 7-Zip, list the entries correctly.
What a dummy ZIP file is used for
Upload limit testing
Archives are a common upload type. Generate a ZIP one byte under, at and over your limit to confirm the first two are accepted and the third is rejected with a clear error.
Extraction and unzip pipelines
Feed a valid archive to your extraction code, background jobs and "upload a ZIP of images" features to check they list, extract and clean up correctly.
Virus and content scanning
Check that antivirus, ICAP and DLP scanners open archives and finish in time for large ones, instead of timing out or passing them unscanned.
Download and bandwidth tests
A 100 MB or 1 GB ZIP is a realistic large download for testing CDN caching, resumable downloads, progress bars and connection speed.
How to test a ZIP upload limit
Test three files around the boundary: one byte under the limit, exactly at it and one byte over. In this tool, set the unit to B and enter the byte counts, for example 104857599, 104857600 and 104857601 for a 100 MB limit. If the same form accepts documents as well as archives, run the three sizes again with a dummy PDF file.
Check which "MB" your stack uses. 100 MB can mean 100,000,000 or 104,857,600 bytes, and 1 MB here is 1,048,576 bytes, so test both boundaries if you are not sure.
Multipart form uploads add headers and boundaries to the request body. A ZIP exactly at a proxy limit such as nginx client_max_body_size can still be rejected, so also test slightly below the documented figure.
| Limit | Size | Notes |
|---|---|---|
| nginx client_max_body_size (default) | 1 MB 1,048,576 B | Requests with a larger body get HTTP 413. |
| PHP upload_max_filesize (default) | 2 MB 2,097,152 B | Also capped by post_max_size, so raise both. |
| AWS Lambda synchronous invocation payload | 6 MB 6,291,456 B | Applies to request and response. |
| Amazon API Gateway REST API payload | 10 MB 10,485,760 B | Hard quota for REST APIs. |
| Outlook default attachment limit (Exchange accounts) | 10 MB 10,485,760 B | Administrators can change it. |
| Outlook attachment limit (internet accounts) | 20 MB 20,971,520 B | Per Microsoft Outlook guidance. |
| Gmail message size limit | 25 MB 26,214,400 B | Attachments grow about a third when encoded, so a 20 MB file can already be too big. |
| Cloudflare proxy request body (Free and Pro plans) | 100 MB 104,857,600 B | Larger requests return HTTP 413. |
Sample ZIP file sizes and the limits they hit
The sizes above are chosen to land near real thresholds. 1 MB is the default nginx request body limit, 10 MB matches the API Gateway REST payload quota, and 100 MB is the Cloudflare proxy limit on Free and Pro plans, and also the largest file size GitHub accepts in a repository. 500 MB and 1 GB are for large-transfer, timeout and storage testing beyond those limits. The table below lists the limits a dummy ZIP can reach.
Validating ZIP uploads safely
Checking the .zip extension is not enough. A robust handler also checks that the file starts with the ZIP signature (the bytes PK, 50 4B 03 04), that the declared uncompressed sizes are reasonable before extracting, and that entry names cannot escape the target folder (paths such as ../). Limit the total extracted size and the number of entries, too. Office files are ZIP archives as well, so a dummy Excel file starts with the same PK bytes: make sure your ZIP check does not accept or reject workbooks by accident.
This dummy ZIP has honest sizes: the stored size equals the extracted size. That makes it a clean baseline. Your size checks should accept it, and your extraction should produce exactly the bytes listed in the central directory.
ZIP file details
- Extension
- ZIP .zip
- MIME type
- application/zip
- Smallest size
- 1 KB
- Largest size
- 1 GB
- Contents
- Valid PK-ZIP archive (stored, no compression) with a README, a JSON manifest and a zero-filled payload file
Dummy ZIP file FAQ
Is the dummy ZIP file a real archive that opens?
Yes. It is a standard ZIP with a central directory. In our checks it passes unzip -t and a 7-Zip integrity test, as well as our own ZIP validator.
What is the largest dummy ZIP file I can download?
Up to 1 GB. The smallest is 1 KB, which is enough for the archive with its README and manifest. Files are assembled in your browser in chunks, but very large ones still depend on your browser and free disk space, so try a smaller size first if a 1 GB download fails.
Can I get a ZIP of an exact size like 100 MB?
Yes. Pick the size and unit and the download matches it to the byte. 100 MB here is 104,857,600 bytes; enter 100000000 with the unit set to B if you need a decimal 100 MB file.
What files are inside the ZIP?
README.txt, sample_manifest.json and archive_payload.dat. The payload file is filled with zero bytes and makes up almost all of the size.
Is the ZIP compressed?
No. Entries are stored without compression, so the ZIP on disk is exactly the size you chose and extracts to about the same size. If you re-compress the extracted payload it shrinks dramatically, because it is all zeros.
Is it safe? Is anything uploaded?
The archive contains only a text file, a JSON file and zero bytes, with no executables or scripts. It is generated in your browser and never uploaded to a server.