To convert images to favicons online for free, you can check these 10 websites as mentioned before.
The following will show you another one — ConvertICO.org, which is also free for you to convert images to ICO files online with 4 special features:
1. You can select the output icon type
After uploading an image (whether PNG, GIF, JPG or BMP format, up to 1 MB) from your computer, or entering the URL of an image, you can select one of the following 4 output icon types:
- ICO for Windows 7, Vista and newer,
- ICO for Windows XP and older,
- Favicon for your website (16px*16px), or
- Custom dimensions.
And for the custom dimensions, you can choose original size or multiple sizes in one icon.
2. You can convert multiple PNG files into one ICO file
You can upload up to 15 PNG files (up to 512 KB) from your computer and convert them into one ICO file with 256px*256px size according to my test.
3. You can batch PNG files
You can upload up to 20 PNG image files (up to 512 KB) and convert every of them to an ICO file with one or more sizes.
4. You can batch ICO files
You can upload up to 20 icon files (up to 512 KB) and convert every of them into one or more PNG, GIF or JPG files.
That's how the ConvertICO.org website works, and if you don't like to convert but to design a new favicon or to download an existing favicon, you can check out these 5 web apps or these 10 websites as mentioned before.