1x1 GIF
1x1 GIF is a Graphics Interchange Format sample generated for file format testing. It can be used to test downloads, parsers, previews, and file type detection.
1x1.gifType Sample
43 B DownloadImage
GIF Graphics Interchange Format
Graphics Interchange Format is a image format commonly identified by .gif. Use the listed signatures, MIME types, and structure notes to validate files beyond the extension.
Extensions .gif
MIME image/gif
Magic numbers
Analyze your fileoffset 0 Graphics Interchange Format leading signature
47 49 46 38 37 61 GIF87aoffset 0 Graphics Interchange Format leading signature
47 49 46 38 39 61 GIF89aStructure
- Header
- Logical screen descriptor
- Global color table
- Image blocks
- Trailer
Caveats
- Do not trust the extension alone. Check the MIME type, the first bytes such as 47 49 46 38 37 61, and format-specific structure when possible.
- Container formats and damaged files can share the same opening bytes, so deeper validation may be required for production upload, preview, or conversion flows.
Detection example
SIGNATURE = bytes.fromhex("474946383761")
OFFSET = 0
def is_gif(path: str) -> bool:
with open(path, "rb") as f:
f.seek(OFFSET)
head = f.read(len(SIGNATURE))
return head == SIGNATUREconst SIGNATURE = [0x47, 0x49, 0x46, 0x38, 0x37, 0x61];
const OFFSET = 0;
// bytes: a Uint8Array / Buffer holding the start of the file
export function isGif(bytes) {
return SIGNATURE.every((byte, i) => bytes[OFFSET + i] === byte);
}package fileid
import "bytes"
var isgifSignature = []byte{0x47, 0x49, 0x46, 0x38, 0x37, 0x61}
const isgifOffset = 0
func IsGif(b []byte) bool {
end := isgifOffset + len(isgifSignature)
if len(b) < end {
return false
}
return bytes.Equal(b[isgifOffset:end], isgifSignature)
}const SIGNATURE: &[u8] = &[0x47, 0x49, 0x46, 0x38, 0x37, 0x61];
const OFFSET: usize = 0;
fn is_gif(bytes: &[u8]) -> bool {
bytes.get(OFFSET..OFFSET + SIGNATURE.len()) == Some(SIGNATURE)
}<?php
$signature = "\x47\x49\x46\x38\x37\x61";
$offset = 0;
function is_gif(string $bytes): bool {
global $signature, $offset;
return substr($bytes, $offset, strlen($signature)) === $signature;
}Practical usage
Use cases
Graphics Interchange Format is commonly used for image previews, thumbnails, metadata checks, and upload validation. Test multiple sizes because resolution, alpha support, compression, and file size often affect implementation behavior.
Common detection mistakes
- The .gif extension alone does not prove the file contents. Upload and conversion flows should combine extension, MIME type, leading bytes, and format-specific structure checks.
- Graphics Interchange Format can start with signatures such as 47 49 46 38 37 61 or 47 49 46 38 39 61, but related containers and damaged files may require additional validation.
Security notes
Media files can still stress decoders through corrupt metadata, extreme dimensions, long durations, or unusual chunks. Read size, dimensions, and duration before processing.
Using samples
11 samples help test tiny images, high-resolution images, alpha channels, and hard-to-compress assets.
Sample files
11 / 11 files
Blue Sky GIF
Blue Sky GIF is a Graphics Interchange Format sample based on Wikimedia Commons, 96 x 72. It can be used to test downloads, parsers, previews, and file type detection.
01-blue-sky.gifResolution 96 x 72 7 Kpx
3.6 KB SHA-256
4fe4554fb7eb8920681a37b43035b8cd6cdb94869ccbbca60d484b47e9371e1d
Flower Garden GIF
Flower Garden GIF is a Graphics Interchange Format sample based on Wikimedia Commons, 160 x 90. It can be used to test downloads, parsers, previews, and file type detection.
02-flower-garden.gifResolution 160 x 90 14 Kpx
8.3 KB SHA-256
eb1da0c8aec6b337ab6abc292a3cda4c8569a39d7e69bf57c16861e6f20315af
Navy Blue Sky GIF
Navy Blue Sky GIF is a Graphics Interchange Format sample based on Wikimedia Commons, 256 x 128. It can be used to test downloads, parsers, previews, and file type detection.
03-navy-blue-sky.gifResolution 256 x 128 33 Kpx
8.8 KB SHA-256
dd308bc7618cc18f8e98e88125947ce91e33cd64ea848fd4aa576f3da7a3a1bd
Nature of the Sky GIF
Nature of the Sky GIF is a Graphics Interchange Format sample based on Wikimedia Commons, 360 x 270. It can be used to test downloads, parsers, previews, and file type detection.
04-nature-sky.gifResolution 360 x 270 97 Kpx
17 KB SHA-256
c6887346eeaf19a2072aa65bcb1b70ef5891913e4fc78e5be85e3e124803876b
Sky Landscape GIF
Sky Landscape GIF is a Graphics Interchange Format sample based on Wikimedia Commons, 512 x 384. It can be used to test downloads, parsers, previews, and file type detection.
05-sky-landscape.gifResolution 512 x 384 197 Kpx
48 KB SHA-256
d4a52af9bb7c49d41ff42926b4708c698a9e03303d33df6a750787b2ebcab072
Starry Sky GIF
Starry Sky GIF is a Graphics Interchange Format sample based on Wikimedia Commons, 720 x 480. It can be used to test downloads, parsers, previews, and file type detection.
06-starry-sky.gifResolution 720 x 480 346 Kpx
86 KB SHA-256
dc373d7e797e546a709403ad8b648f630f1c2e78fb1dbc78247527789c6a0f99
Blue Night Sky GIF
Blue Night Sky GIF is a Graphics Interchange Format sample based on Wikimedia Commons, 960 x 640. It can be used to test downloads, parsers, previews, and file type detection.
07-blue-night-sky.gifResolution 960 x 640 614 Kpx
277 KB SHA-256
ad72a17789fbe7f26e9691fd6355e3672c4f7d2ba7d8dbd2d0a2942eb5d3fa7b
Hibiscus Flower GIF
Hibiscus Flower GIF is a Graphics Interchange Format sample based on Wikimedia Commons, 1280 x 2770. It can be used to test downloads, parsers, previews, and file type detection.
08-hibiscus-flower.gifResolution 1280 x 2770 3.5 MP
1.34 MB SHA-256
1284d2d2ae1365187adee386b5630766fb5452e2f61189342888b5adddf42065
Arctic Sky GIF
Arctic Sky GIF is a Graphics Interchange Format sample based on Wikimedia Commons, 1600 x 1062. It can be used to test downloads, parsers, previews, and file type detection.
09-arctic-sky.gifResolution 1600 x 1062 1.7 MP
625 KB SHA-256
8c3e6a7a91f978f524a5b885c955ad22b912c71e62f7e6119a2b133c46499fd7
NASA Blue Marble GIF
NASA Blue Marble GIF is a Graphics Interchange Format sample based on NASA Image and Video Library, 640 x 640. It can be used to test downloads, parsers, previews, and file type detection.
nasa-blue-marble-2012-east.gifResolution 640 x 640 410 Kpx
112 KB SHA-256
102a04cf58beec5478958cc4d88bf5b2ddd21d19aef22a2f3b67bb2e3f4f0760
Frequently asked questions
What is the magic number (file signature) of Graphics Interchange Format?
Graphics Interchange Format files begin with the byte signature 47 49 46 38 37 61 ("GIF87a") or 47 49 46 38 39 61 ("GIF89a"). Detect the format by reading these leading bytes rather than trusting the file extension alone.
What is the MIME type of Graphics Interchange Format?
The MIME type for Graphics Interchange Format is image/gif.
What file extension does Graphics Interchange Format use?
Graphics Interchange Format files use the .gif extension. The extension is a convention only and does not guarantee the file contents, so combine it with signature and structure checks.