PNG MIME Type

About PNG image files

Lossless, with full transparency, which makes it the format for screenshots, logos and UI graphics. Photos as PNG are several times larger than JPEG, WebP or AVIF. PNG data is already deflate-compressed, so don’t gzip it again on the server; use an optimizer such as oxipng instead.

File signature

PNG files start with 89 50 4E 47 0D 0A 1A 0A ("\x89PNG\r\n\x1a\n"). The extension and the type a browser reports for an upload both come from the file name, so check these bytes on the server before trusting a file.

Serve .png with the right Content-Type

Content-Type: image/png

image/png png;

AddType image/png .png

@png path *.png
header @png Content-Type "image/png"

curl -sI https://example.com/file.png | grep -i '^content-type'
# Content-Type: image/png

Set the type in code

res.set('Content-Type', 'image/png');
// Or make the browser download it:
res.attachment('file.png');

import mimetypes

mimetypes.add_type('image/png', '.png')  # if your system doesn't know it
mimetypes.guess_type('file.png')[0]  # 'image/png'

mime.AddExtensionType(".png", "image/png")
w.Header().Set("Content-Type", "image/png")

Accept .png uploads

<input type="file" accept=".png,image/png">

The accept attribute only filters the file picker; users can still choose another file. Listing the extension as well as the type matters, because operating systems don’t always report the type you expect.

Related types

• .jpg (image/jpeg): JPEG image
• .webp (image/webp): WebP image
• .avif (image/avif): AVIF image
• .svg (image/svg+xml): SVG image

More images

.gif , .heic , .ico , .bmp , .tiff . Look up any extension or type with the MIME type lookup.

Sources

• IANA registration: image/png
• MDN: Common media types

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Frequently asked questions