# What is CORS ?
Cross Origin Resource Sharing
Meaning a security mechanism, which allows web applications to access resources hosted on different domains/origins.
Example: We have an API running on our localhost. We want to access this API through our Blazor Application. When we want to access the APIs data we get the following response:
Access to fetch at 'https://localhost:7246/WeatherForecast' from origin 'http://localhost:3000'
has been blocked by CORS policy:
No 'Access-Control-Allow-Origin' header is present on the requested resource.
If an opaque response serves your needs, set the request's mode to 'no-cors'
to fetch the resource with CORS disabled.# Enabling CORS
// Program.cs
var corsOrigin = "corsOrigin";
builder.Services.AddCors(options =>
{
options.AddPolicy(corsOrigin,
policy =>
{
policy.AllowAnyMethod()
.AllowAnyHeader()
.AllowAnyOrigin();
});
});
app.UseCors(corsOrigin);OR
// Program.cs
builder.Services.AddCors();
app.UseCors(cpb =>
{
cpb.AllowAnyHeader()
.AllowAnyMethod()
.AllowAnyOrigin();
});