Free WEBP test files and sample generator
Modern web image format with strong lossy and lossless compression. Smaller than PNG/JPG at similar quality.
What is a .webp file?
WEBP: WebP Image. WebP is Google's image format offering smaller files than JPEG or PNG at similar quality. Modern browsers support it universally, but older tooling and libraries often do not, which is what makes it worth testing.
Why generate a test WEBP file?
- Verify your upload path and image library actually support WebP.
- Test format-conversion fallbacks for older clients.
- Check that content-type sniffing identifies it correctly.
What you can put inside a .webp file
You get 4 content options for WEBP, so the file holds something meaningful rather than random padding: Image, Bar chart, Pie chart, QR code. Pick several and they are merged into one file, with a section, sheet, slide or folder for each.
How a .webp file is identified
Every .webp file begins with 52 49 46 46 … 57 45 42 50, "RIFF", then the length, then "WEBP" at offset 8. That is what a validator inspecting content rather than the file name looks for.
How the size lands on the exact byte
The image is encoded by the browser, then padded past the length declared in the RIFF header. A decoder stops at the declared length, so the extra bytes never reach it.
Negative testing with broken WEBP files
- Invalid. Identifiable, but wrong inside, so it fails during parsing.
- Corrupted. The leading bytes are destroyed, so the
52 49 46 46 … 57 45 42 50identifying a .webp is gone. Same length as the valid file. - Incomplete. Truncated part-way, so it is genuinely shorter.
- Empty. Chosen under Content rather than File Condition: valid structure, no data.
Which failure to reach for, and what to assert for each, is covered in how to make a corrupted file for testing. For upload limits and type checks see testing file upload validation.
Sample WEBP content
[Binary image], 1920×1080, lossy, ~30% smaller than JPG.
This shows the shape of the file. Your download is generated fresh at the size you choose, so the values will differ.
How to open and verify the file
Open in any modern browser; inspect with `webpinfo` or ImageMagick.
Media type image/webp · extension .webp · category Images
Generate a .webp file → · questions about sizes, privacy or cost are answered on the site FAQ.
Frequently asked questions about WEBP files
What identifies a .webp file?
A .webp file begins with the bytes 52 49 46 46 … 57 45 42 50, "RIFF", then the length, then "WEBP" at offset 8. Those bytes are what a content-sniffing validator looks for, and what the Corrupted condition destroys.
How can a .webp file be an exact number of bytes?
The image is encoded by the browser, then padded past the length declared in the RIFF header. A decoder stops at the declared length, so the extra bytes never reach it.
What can go inside the WEBP file?
There are 4 content options for .webp: Image, Bar chart, Pie chart, QR code. Choose more than one and they are combined into a single file, a section, sheet, slide or folder per option, rather than downloaded separately.
Can I download several broken WEBP files at once?
Yes, select more than one File Condition and you get one ZIP containing a .webp per condition, each named after its condition.
Can the WEBP file use UTF-16 or a byte-order mark?
No, and deliberately. A .webp file is a container rather than plain text, so rewriting its bytes as UTF-16 would not produce a UTF-16 document. It would produce a broken file. Use a text format such as CSV, JSON or XML for encoding tests.
How do I open or verify the WEBP file?
Open in any modern browser; inspect with webpinfo or ImageMagick.