It depends on the type of contest you are running.
- For a logo design or related category, the contest holder should ask for a vectorized image in either of the two file formats listed below:
- a PDF file (which is a universal file format), or
- an Adobe Illustrator AI file.
If the contest holder wants to view the design without downloading any software, they can ask the designer to provide a JPEG, GIF, or PNG file.
- For website design related category, contest holder should ask for a layered Photoshop PSD file.
- For print design contests, please consult with your printer what file formats they require.
- a PDF file in 300 dpi (dots per inch) CMYK image format, or
- an Adobe Illustrator (.ai) file or Adobe InDesign (.indd) file or Adobe Photoshop (.psd)
The contest holders don’t need to ask the designer to provide any of the files for the font they used in the design, since font licenses are usually non-transferrable. But they can ask the designer for the name of the font so the contest holders can buy a license if they need to.
For a comprehensive idea on files and formats you may require for a contest, please refer to this guide.