In a website will not be separated from the use of fonts. Among the free font web providers is Google Fonts . How to use custom fonts from Google Fonts is quite easy because the external CSS from the font is already provided. Stay copied and installed on the web.

Unfortunately however, the use of external CSS links such as CSS links for Google Fonts will cause
CSS blocking rendering
.For example CSS links for Google Fonts like the following:

<link href="https://fonts.googleapis.com/css?family=Open+Sans:300,300i,400,400i,600,600i,700,700i,800,800i" rel="stylesheet"> 

Roboto:

@font-face {
  font-family: 'Roboto';
  font-style: normal;
  font-weight: 300;
  src: local('Roboto Light'), local('Roboto-Light'), url(https://fonts.gstatic.com/s/roboto/v16/Hgo13k-tfSpn0qi1SFdUfVtXRa8TVwTICgirnJhmVJw.woff2) format('woff2'), url(https://fonts.gstatic.com/s/roboto/v16/Hgo13k-tfSpn0qi1SFdUfT8E0i7KZn-EPnyo3HZu7kw.woff) format('woff'),url(https://fonts.gstatic.com/s/roboto/v16/Hgo13k-tfSpn0qi1SFdUfSZ2oysoEQEeKwjgmXLRnTc.ttf) format('truetype');
}
@font-face {
  font-family: 'Roboto';
  font-style: normal;
  font-weight: 400;
  src: local('Roboto'), local('Roboto-Regular'), url(https://fonts.gstatic.com/s/roboto/v16/CWB0XYA8bzo0kSThX0UTuA.woff2) format('woff2'), url(https://fonts.gstatic.com/s/roboto/v16/2UX7WLTfW3W8TclTUvlFyQ.woff) format('woff'),url(https://fonts.gstatic.com/s/roboto/v16/QHD8zigcbDB8aPfIoaupKOvvDin1pK8aKteLpeZ5c0A.ttf) format('truetype');
}
@font-face {
  font-family: 'Roboto';
  font-style: normal;
  font-weight: 500;
  src: local('Roboto Medium'), local('Roboto-Medium'), url(https://fonts.gstatic.com/s/roboto/v16/RxZJdnzeo3R5zSexge8UUVtXRa8TVwTICgirnJhmVJw.woff2) format('woff2'), url(https://fonts.gstatic.com/s/roboto/v16/RxZJdnzeo3R5zSexge8UUT8E0i7KZn-EPnyo3HZu7kw.woff) format('woff'),url(https://fonts.gstatic.com/s/roboto/v16/RxZJdnzeo3R5zSexge8UUSZ2oysoEQEeKwjgmXLRnTc.ttf) format('truetype');
}
@font-face {
  font-family: 'Roboto';
  font-style: normal;
  font-weight: 700;
  src: local('Roboto Bold'), local('Roboto-Bold'), url(https://fonts.gstatic.com/s/roboto/v16/d-6IYplOFocCacKzxwXSOFtXRa8TVwTICgirnJhmVJw.woff2) format('woff2'), url(https://fonts.gstatic.com/s/roboto/v16/d-6IYplOFocCacKzxwXSOD8E0i7KZn-EPnyo3HZu7kw.woff) format('woff'),url(https://fonts.gstatic.com/s/roboto/v16/d-6IYplOFocCacKzxwXSOCZ2oysoEQEeKwjgmXLRnTc.ttf) format('truetype');
}
@font-face {
  font-family: 'Roboto';
  font-style: normal;
  font-weight: 900;
  src: local('Roboto Black'), local('Roboto-Black'), url(https://fonts.gstatic.com/s/roboto/v16/mnpfi9pxYH-Go5UiibESIltXRa8TVwTICgirnJhmVJw.woff2) format('woff2'), url(https://fonts.gstatic.com/s/roboto/v16/mnpfi9pxYH-Go5UiibESIj8E0i7KZn-EPnyo3HZu7kw.woff) format('woff'),url(https://fonts.gstatic.com/s/roboto/v16/mnpfi9pxYH-Go5UiibESIiZ2oysoEQEeKwjgmXLRnTc.ttf) format('truetype');
}
@font-face {
  font-family: 'Roboto';
  font-style: italic;
  font-weight: 300;
  src: local('Roboto Light Italic'), local('Roboto-LightItalic'), url(https://fonts.gstatic.com/s/roboto/v16/7m8l7TlFO-S3VkhHuR0at44P5ICox8Kq3LLUNMylGO4.woff2) format('woff2'), url(https://fonts.gstatic.com/s/roboto/v16/7m8l7TlFO-S3VkhHuR0at4bN6UDyHWBl620a-IRfuBk.woff) format('woff'),url(https://fonts.gstatic.com/s/roboto/v16/7m8l7TlFO-S3VkhHuR0atywlidHJgAgmTjOEEzwu1L8.ttf) format('truetype');
}
@font-face {
  font-family: 'Roboto';
  font-style: italic;
  font-weight: 400;
  src: local('Roboto Italic'), local('Roboto-Italic'), url(https://fonts.gstatic.com/s/roboto/v16/vPcynSL0qHq_6dX7lKVByfesZW2xOQ-xsNqO47m55DA.woff2) format('woff2'), url(https://fonts.gstatic.com/s/roboto/v16/1pO9eUAp8pSF8VnRTP3xnvesZW2xOQ-xsNqO47m55DA.woff) format('woff'),url(https://fonts.gstatic.com/s/roboto/v16/W4wDsBUluyw0tK3tykhXEXYhjbSpvc47ee6xR_80Hnw.ttf) format('truetype');
}
@font-face {
  font-family: 'Roboto';
  font-style: italic;
  font-weight: 500;
  src: local('Roboto Medium Italic'), local('Roboto-MediumItalic'), url(https://fonts.gstatic.com/s/roboto/v16/OLffGBTaF0XFOW1gnuHF0Y4P5ICox8Kq3LLUNMylGO4.woff2) format('woff2'), url(https://fonts.gstatic.com/s/roboto/v16/OLffGBTaF0XFOW1gnuHF0YbN6UDyHWBl620a-IRfuBk.woff) format('woff'),url(https://fonts.gstatic.com/s/roboto/v16/OLffGBTaF0XFOW1gnuHF0SwlidHJgAgmTjOEEzwu1L8.ttf) format('truetype');
}
@font-face {
  font-family: 'Roboto';
  font-style: italic;
  font-weight: 700;
  src: local('Roboto Bold Italic'), local('Roboto-BoldItalic'), url(https://fonts.gstatic.com/s/roboto/v16/t6Nd4cfPRhZP44Q5QAjcC44P5ICox8Kq3LLUNMylGO4.woff2) format('woff2'), url(https://fonts.gstatic.com/s/roboto/v16/t6Nd4cfPRhZP44Q5QAjcC4bN6UDyHWBl620a-IRfuBk.woff) format('woff'),url(https://fonts.gstatic.com/s/roboto/v16/t6Nd4cfPRhZP44Q5QAjcCywlidHJgAgmTjOEEzwu1L8.ttf) format('truetype');
}
@font-face {
  font-family: 'Roboto';
  font-style: italic;
  font-weight: 900;
  src: local('Roboto Black Italic'), local('Roboto-BlackItalic'), url(https://fonts.gstatic.com/s/roboto/v16/bmC0pGMXrhphrZJmniIZpY4P5ICox8Kq3LLUNMylGO4.woff2) format('woff2'), url(https://fonts.gstatic.com/s/roboto/v16/bmC0pGMXrhphrZJmniIZpYbN6UDyHWBl620a-IRfuBk.woff) format('woff'),url(https://fonts.gstatic.com/s/roboto/v16/bmC0pGMXrhphrZJmniIZpSwlidHJgAgmTjOEEzwu1L8.ttf) format('truetype');
}

Open Sans:

@font-face {
  font-family: 'Open Sans';
  font-style: normal;
  font-weight: 300;
  src: local('Open Sans Light'), local('OpenSans-Light'), url(https://fonts.gstatic.com/s/opensans/v14/DXI1ORHCpsQm3Vp6mXoaTegdm0LZdjqr5-oayXSOefg.woff2) format('woff2'), url(https://fonts.gstatic.com/s/opensans/v14/DXI1ORHCpsQm3Vp6mXoaTXhCUOGz7vYGh680lGh-uXM.woff) format('woff'),url(https://fonts.gstatic.com/s/opensans/v14/DXI1ORHCpsQm3Vp6mXoaTZS3E-kSBmtLoNJPDtbj2Pk.ttf) format('truetype');
}
@font-face {
  font-family: 'Open Sans';
  font-style: normal;
  font-weight: 400;
  src: local('Open Sans Regular'), local('OpenSans-Regular'), url(https://fonts.gstatic.com/s/opensans/v14/cJZKeOuBrn4kERxqtaUH3VtXRa8TVwTICgirnJhmVJw.woff2) format('woff2'), url(https://fonts.gstatic.com/s/opensans/v14/cJZKeOuBrn4kERxqtaUH3T8E0i7KZn-EPnyo3HZu7kw.woff) format('woff'),url(https://fonts.gstatic.com/s/opensans/v14/cJZKeOuBrn4kERxqtaUH3SZ2oysoEQEeKwjgmXLRnTc.ttf) format('truetype');
}
@font-face {
  font-family: 'Open Sans';
  font-style: normal;
  font-weight: 600;
  src: local('Open Sans SemiBold'), local('OpenSans-SemiBold'), url(https://fonts.gstatic.com/s/opensans/v14/MTP_ySUJH_bn48VBG8sNSugdm0LZdjqr5-oayXSOefg.woff2) format('woff2'), url(https://fonts.gstatic.com/s/opensans/v14/MTP_ySUJH_bn48VBG8sNSnhCUOGz7vYGh680lGh-uXM.woff) format('woff'),url(https://fonts.gstatic.com/s/opensans/v14/MTP_ySUJH_bn48VBG8sNSpS3E-kSBmtLoNJPDtbj2Pk.ttf) format('truetype');
}
@font-face {
  font-family: 'Open Sans';
  font-style: normal;
  font-weight: 700;
  src: local('Open Sans Bold'), local('OpenSans-Bold'), url(https://fonts.gstatic.com/s/opensans/v14/k3k702ZOKiLJc3WVjuplzOgdm0LZdjqr5-oayXSOefg.woff2) format('woff2'), url(https://fonts.gstatic.com/s/opensans/v14/k3k702ZOKiLJc3WVjuplzHhCUOGz7vYGh680lGh-uXM.woff) format('woff'),url(https://fonts.gstatic.com/s/opensans/v14/k3k702ZOKiLJc3WVjuplzJS3E-kSBmtLoNJPDtbj2Pk.ttf) format('truetype');
}
@font-face {
  font-family: 'Open Sans';
  font-style: normal;
  font-weight: 800;
  src: local('Open Sans ExtraBold'), local('OpenSans-ExtraBold'), url(https://fonts.gstatic.com/s/opensans/v14/EInbV5DfGHOiMmvb1Xr-hugdm0LZdjqr5-oayXSOefg.woff2) format('woff2'), url(https://fonts.gstatic.com/s/opensans/v14/EInbV5DfGHOiMmvb1Xr-hnhCUOGz7vYGh680lGh-uXM.woff) format('woff'),url(https://fonts.gstatic.com/s/opensans/v14/EInbV5DfGHOiMmvb1Xr-hpS3E-kSBmtLoNJPDtbj2Pk.ttf) format('truetype');
}
@font-face {
  font-family: 'Open Sans';
  font-style: italic;
  font-weight: 300;
  src: local('Open Sans Light Italic'), local('OpenSans-LightItalic'), url(https://fonts.gstatic.com/s/opensans/v14/PRmiXeptR36kaC0GEAetxko2lTMeWA_kmIyWrkNCwPc.woff2) format('woff2'), url(https://fonts.gstatic.com/s/opensans/v14/PRmiXeptR36kaC0GEAetxh_xHqYgAV9Bl_ZQbYUxnQU.woff) format('woff'),url(https://fonts.gstatic.com/s/opensans/v14/PRmiXeptR36kaC0GEAetxt6Naowg1QhaIq8kLGtQSos.ttf) format('truetype');
}
@font-face {
  font-family: 'Open Sans';
  font-style: italic;
  font-weight: 400;
  src: local('Open Sans Italic'), local('OpenSans-Italic'), url(https://fonts.gstatic.com/s/opensans/v14/xjAJXh38I15wypJXxuGMBo4P5ICox8Kq3LLUNMylGO4.woff2) format('woff2'), url(https://fonts.gstatic.com/s/opensans/v14/xjAJXh38I15wypJXxuGMBobN6UDyHWBl620a-IRfuBk.woff) format('woff'),url(https://fonts.gstatic.com/s/opensans/v14/xjAJXh38I15wypJXxuGMBiwlidHJgAgmTjOEEzwu1L8.ttf) format('truetype');
}
@font-face {
  font-family: 'Open Sans';
  font-style: italic;
  font-weight: 600;
  src: local('Open Sans SemiBold Italic'), local('OpenSans-SemiBoldItalic'), url(https://fonts.gstatic.com/s/opensans/v14/PRmiXeptR36kaC0GEAetxl2umOyRU7PgRiv8DXcgJjk.woff2) format('woff2'), url(https://fonts.gstatic.com/s/opensans/v14/PRmiXeptR36kaC0GEAetxn5HxGBcBvicCpTp6spHfNo.woff) format('woff'),url(https://fonts.gstatic.com/s/opensans/v14/PRmiXeptR36kaC0GEAetxs1QGe9x6ME_FQCWJB3n6z8.ttf) format('truetype');
}
@font-face {
  font-family: 'Open Sans';
  font-style: italic;
  font-weight: 700;
  src: local('Open Sans Bold Italic'), local('OpenSans-BoldItalic'), url(https://fonts.gstatic.com/s/opensans/v14/PRmiXeptR36kaC0GEAetxolIZu-HDpmDIZMigmsroc4.woff2) format('woff2'), url(https://fonts.gstatic.com/s/opensans/v14/PRmiXeptR36kaC0GEAetxjqR_3kx9_hJXbbyU8S6IN0.woff) format('woff'),url(https://fonts.gstatic.com/s/opensans/v14/PRmiXeptR36kaC0GEAetxjdGNerWpg2Hn6A-BxWgZ_I.ttf) format('truetype');
}
@font-face {
  font-family: 'Open Sans';
  font-style: italic;
  font-weight: 800;
  src: local('Open Sans ExtraBold Italic'), local('OpenSans-ExtraBoldItalic'), url(https://fonts.gstatic.com/s/opensans/v14/PRmiXeptR36kaC0GEAetxnibbpXgLHK_uTT48UMyjSM.woff2) format('woff2'), url(https://fonts.gstatic.com/s/opensans/v14/PRmiXeptR36kaC0GEAetxkCDe67GEgBv_HnyvHTfdew.woff) format('woff'),url(https://fonts.gstatic.com/s/opensans/v14/PRmiXeptR36kaC0GEAetxkdJXfhP-2RmnAuS9A2rxpE.ttf) format('truetype');
}