Free AVIF test files and sample generator
Modern image format based on the AV1 codec, offering excellent compression and quality.
What is a .avif file?
AVIF: AV1 Image File Format. AVIF is a still image, but not a simple one: it is a single AV1 keyframe wrapped in the same HEIF container that HEIC uses. That means the picture is not stored as a stream but as an item: a metadata box describes it, records its dimensions and codec configuration as properties, marks which of those properties are essential, and points at the compressed bytes by absolute file offset. Get that offset wrong by one byte and every decoder refuses the file. AVIF typically beats JPEG substantially at the same quality, which is why browsers adopted it quickly.
Why generate a test AVIF file?
- Test an image upload path with a modern format older tooling may not know.
- Exercise format detection and thumbnail generation for HEIF-family files.
- Check graceful fallback when a library cannot decode AVIF.
What you can put inside a .avif file
You get 3 content options for AVIF, so the file holds something meaningful rather than random padding: Logo motion, Color bars, Timer / counter. For AVIF these are alternatives, so choose the one that matches what you need to test.
How a .avif file is identified
Every .avif file begins at offset 4 with 66 74 79 70, "ftyp" at offset 4, with an AVIF brand. That is what a validator inspecting content rather than the file name looks for.
Negative testing with broken AVIF files
- Invalid. Identifiable, but wrong inside, so it fails during parsing.
- Corrupted. The leading bytes are destroyed, so the
66 74 79 70identifying a .avif 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 AVIF content
[Binary image], AV1, HDR-capable, unusually small.
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 it in any recent browser, which decodes AVIF natively, or inspect the box tree with `exiftool` / `ffprobe`. Files here are 320x240 AV1 keyframes encoded by your own browser and wrapped by hand, verified by handing them back to the browser's own decoder, which reads them at the correct dimensions.
Media type image/avif · extension .avif · category Images
Generate a .avif file → · questions about sizes, privacy or cost are answered on the site FAQ.
Frequently asked questions about AVIF files
What identifies a .avif file?
A .avif file begins at offset 4 with the bytes 66 74 79 70, "ftyp" at offset 4, with an AVIF brand. Those bytes are what a content-sniffing validator looks for, and what the Corrupted condition destroys.
What can go inside the AVIF file?
There are 3 content options for .avif: Logo motion, Color bars, Timer / counter. For AVIF these are alternatives, so pick the one matching what you need to test.
Can I download several broken AVIF files at once?
Yes, select more than one File Condition and you get one ZIP containing a .avif per condition, each named after its condition.
Can the AVIF file use UTF-16 or a byte-order mark?
No, and deliberately. A .avif 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 AVIF file?
Open it in any recent browser, which decodes AVIF natively, or inspect the box tree with exiftool / ffprobe. Files here are 320x240 AV1 keyframes encoded by your own browser and wrapped by hand, verified by handing them back to the browser's own decoder, which reads them at the correct dimensions.