8.7Setting the default User-Agent

Created on Aug 17, 2026~1 min read

When sending an HTTP request, if the user does not specify a User-Agent request header, the framework uses the Edge browser (version 142) User-Agent by default. The example is as follows:

text
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36 Edg/142.0.0.0

To customize the default User-Agent, use the following approaches:

Global configuration:

cs
// Configure the default client's User-Agentservices.AddHttpClient(string.Empty, client =>{    client.DefaultRequestHeaders.Add("User-Agent", UserAgents.Chrome.PC);   // Recommended: use the UserAgents static class    // client.DefaultRequestHeaders.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36 Edg/142.0.0.0"); // Or set the User-Agent string directly});

Per-request configuration:

cs
HttpRequestBuilder.Post("https://furion.net/")    .SetUserAgent(UserAgents.Chrome.PC);   // Recommended: use the UserAgents static class    // .SetUserAgent("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36 Edg/142.0.0.0");   // Or set the User-Agent string directly    // .WithHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36 Edg/142.0.0.0", replace: true);   // Or use the WithHeader method