Telerik UI for Blazor CDN
The Telerik Blazor CDN is a complimentary service that can be used in development and production environments. This article describes the CDN URLs and what to keep in mind when using CDN in general.
The CDN hosts theme CSS files for the Telerik UI for Blazor components.
The
blazor.cdn.telerik.comCDN is deprecated and will be shut down in the future. The newest CSS files that it hosts are for version15.1.0released in October 2026. Useunpkg.cominstead.
CSS Theme URLs
The Telerik CSS themes are available on the unpkg.com host. It provides all built-in theme swatches. The version number in the theme URL matches the version of the theme itself. Make sure to use compatible theme and component versions. For example, use theme version 14.6.1 with UI for Blazor version 15.1.0.
The CSS file URLs on unpkg.com look like this:
unpkg.com/@progress/kendo-theme-<THEME-NAME>@<THEME-VERSION>/dist/<SWATCH-NAME>.css
The separate font icons stylesheet URL looks like this:
unpkg.com/@progress/kendo-font-icons@<PACKAGE-VERSION>/dist/index.css
Here are a few examples. Note the duplicate At signs @. This syntax is compatible with .razor files. When loading a theme from index.html, use just one @.
UNPKG CDN URLs for Telerik CSS themes
<!-- Main swatch of the Meridian theme -->
<link rel="stylesheet" href="https://unpkg.com/@@progress/kendo-theme-meridian@@14.6.1/dist/meridian-main.css" />
<!-- Ocean Blue swatch of the Default theme -->
<link rel="stylesheet" href="https://unpkg.com/@@progress/kendo-theme-default@@14.6.1/dist/default-ocean-blue.css" />
<!-- Main swatch of the Bootstrap theme -->
<link rel="stylesheet" href="https://unpkg.com/@@progress/kendo-theme-bootstrap@@14.6.1/dist/bootstrap-main.css" />
<!-- Latest font icon stylesheet. Using a version number instead of latest is recommended with older component versions. -->
<link rel="stylesheet" href="https://unpkg.com/@@progress/kendo-font-icons@@latest/dist/index.css" />Pros and Cons of Using CDN
The benefits of using a CDN in Blazor apps are:
- Possible performance gains in the application loading time. Blazor apps are single page applications and browsers rely on cache by default, so this benefit is marginal and relates only to users that open the application for the first time.
- Avoidance of browser caching issues after component version upgrades. The CSS and JS files change with every component version, and so do the CDN URLs. This URL change guarantees that browsers will reload the static assets.
The drawbacks of using a CDN are:
- Additional component version upgrade steps. You must change the version number in the URL, otherwise the application can display broken UI or throw JavaScript errors.
- A CDN is a critical external dependency for your app. Regardless of the claimed uptime, you must implement a CDN fallback for cases when the CDN is not accessible to your users due to geographical, networking or system issues.