It depends on the type of contest you are running.
For a logo design or related category, you 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 you want to view the design without downloading any software, you can ask the designer to provide a JPEG, GIF, or PNG file.
For website design related category, you 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)
Don’t ask the designer to provide any of the files for the font they used in your design, since font licenses are usually non-transferrable. But do ask the designer for the name of the font so you can buy a license if you need to.