Authentication Swagger with JWT Bearer token

Update - The Swagger spec has changed. check answer by @nilay below for the correct solution.

I had the very same problem.

2 things are neccessary

1. You have to put "bearer <token-here>" like this. Putting only token will not work.

to get this to work in swagger 2.x, you need to accompany your scheme definition with a corresponding requirement to indicate that the scheme is applicable to all operations in your API:

c.AddSecurityRequirement(new Dictionary<string, IEnumerable<string>>
{
    { "Bearer", new string[] { } }
});

Complete definition:

services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new Info { Title = "Some API", Version = "v1" });
                c.AddSecurityDefinition("Bearer", new ApiKeyScheme()
                {
                    Description = "JWT Authorization header using the Bearer scheme. Example: \"Authorization: Bearer {token}\"",
                    Name = "Authorization",
                    In = "header",
                    Type = "apiKey"
                });
                c.AddSecurityRequirement(new Dictionary<string, IEnumerable<string>>
                {
                    { "Bearer", new string[] { } }
                });
            });

I also face same issue, but I am using new version of Swagger which is based on OpenAPI. So, I have to use below snippet for same.

var securityScheme = new OpenApiSecurityScheme()
{
    Description = "JWT Authorization header using the Bearer scheme. Example: \"Authorization: Bearer {token}\"",
    Name = "Authorization",
    In = ParameterLocation.Header,
    Type = SecuritySchemeType.Http,
    Scheme = "bearer",
    BearerFormat = "JWT"
};

var securityRequirement = new OpenApiSecurityRequirement
{
    {
            new OpenApiSecurityScheme
            {
                Reference = new OpenApiReference
                {
                    Type = ReferenceType.SecurityScheme,
                    Id = "bearerAuth"
                }
            },
            new string[] {}
    }
};

options.AddSecurityDefinition("bearerAuth", securityScheme);
options.AddSecurityRequirement(securityRequirement);