If you want to self-host Google fonts for your server, you can use the following free service:
https://google-webfonts-helper.herokuapp.com/
That is a great site to use Google font offline!
Add unicode-range property to increase site performace.
Let say your website has an online Google font called Karla and your site call the font using the following API:
https://fonts.googleapis.com/css?family=Karla:400,700
When you open the above URL in a browser you will see the following output:
/* latin-ext */
@font-face {
font-family: 'Karla';
font-style: normal;
font-weight: 400;
src: url(https://fonts.gstatic.com/s/karla/v15/qkBbXvYC6trAT7RbLtyG5Q.woff2) format('woff2');
unicode-range: U+0100-024F, U+0259, U+1E00-1EFF, U+2020, U+20A0-20AB, U+20AD-20CF, U+2113, U+2C60-2C7F, U+A720-A7FF;
}
/* latin */
@font-face {
font-family: 'Karla';
font-style: normal;
font-weight: 400;
src: url(https://fonts.gstatic.com/s/karla/v15/qkBbXvYC6trAT7RVLtw.woff2) format('woff2');
unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
/* latin-ext */
@font-face {
font-family: 'Karla';
font-style: normal;
font-weight: 700;
src: url(https://fonts.gstatic.com/s/karla/v15/qkBbXvYC6trAT7RbLtyG5Q.woff2) format('woff2');
unicode-range: U+0100-024F, U+0259, U+1E00-1EFF, U+2020, U+20A0-20AB, U+20AD-20CF, U+2113, U+2C60-2C7F, U+A720-A7FF;
}
/* latin */
@font-face {
font-family: 'Karla';
font-style: normal;
font-weight: 700;
src: url(https://fonts.gstatic.com/s/karla/v15/qkBbXvYC6trAT7RVLtw.woff2) format('woff2');
unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
The above is the font CSS definition and it already contains some unicode ranges that will make the fonts load only necessary blocks to increase site performance. See the unicode-range and why you should use it. Use the above online service to generate offline Google fonts, upload them to your website then add an additional unicode-range for each font definition.
