Use JWT (Authorization: Bearer) in Swagger in ASP.NET Core

Currently Swagger has functionality for authentication with JWT-token and can automatically add token into header (I'm using Swashbuckle.AspNetCore 1.1.0).

The following code should help achieve this.

In the Startup.ConfigureServices():

services.AddSwaggerGen(c =>
{
    // Your custom configuration
    c.SwaggerDoc("v1", new Info { Title = "My API", Version = "v1" });
    c.DescribeAllEnumsAsStrings();
    // JWT-token authentication by password
    c.AddSecurityDefinition("oauth2", new OAuth2Scheme
    {
        Type = "oauth2",
        Flow = "password",
        TokenUrl = Path.Combine(HostingEnvironment.WebRootPath, "/token"),
        // Optional scopes
        //Scopes = new Dictionary<string, string>
        //{
        //    { "api-name", "my api" },
        //}
    });
});

Check and configure TokenUrl if your endpoint is different.

In the Startup.Configure():

app.UseSwagger();
app.UseSwaggerUI(c =>
{
    c.SwaggerEndpoint("/swagger/v1/swagger.json", "API V1");

    // Provide client ID, client secret, realm and application name (if need)

    // Swashbuckle.AspNetCore 4.0.1
    c.OAuthClientId("swagger-ui");
    c.OAuthClientSecret("swagger-ui-secret");
    c.OAuthRealm("swagger-ui-realm");
    c.OAuthAppName("Swagger UI");

    // Swashbuckle.AspNetCore 1.1.0
    // c.ConfigureOAuth2("swagger-ui", "swagger-ui-secret", "swagger-ui-realm", "Swagger UI");
});

If your endpoint for authentication by token follows the OAuth2 standard, all should work. But just in case, I have added sample of this endpoint:

public class AccountController : Controller
{
    [ProducesResponseType(typeof(AccessTokens), (int)HttpStatusCode.OK)]
    [ProducesResponseType((int)HttpStatusCode.BadRequest)]
    [ProducesResponseType((int)HttpStatusCode.Unauthorized)]
    [HttpPost("/token")]
    public async Task<IActionResult> Token([FromForm] LoginModel loginModel)
    {
        switch (loginModel.grant_type)
        {
            case "password":
                var accessTokens = // Authentication logic
                if (accessTokens == null)
                    return BadRequest("Invalid user name or password.");
                return new ObjectResult(accessTokens);

            case "refresh_token":
                var accessTokens = // Refresh token logic
                if (accessTokens == null)
                    return Unauthorized();
                return new ObjectResult(accessTokens);

            default:
                return BadRequest("Unsupported grant type");
        }
    }
}

public class LoginModel
{
    [Required]
    public string grant_type { get; set; }

    public string username { get; set; }
    public string password { get; set; }
    public string refresh_token { get; set; }
    // Optional
    //public string scope { get; set; }
}

public class AccessTokens
{
    public string access_token { get; set; }
    public string refresh_token { get; set; }
    public string token_type { get; set; }
    public int expires_in { get; set; }
}

I struggled with the same problem and found a working solution in this blogpost: http://blog.sluijsveld.com/28/01/2016/CustomSwaggerUIField

It comes down to adding this in your configurationoptions

services.ConfigureSwaggerGen(options =>
{
   options.OperationFilter<AuthorizationHeaderParameterOperationFilter>();
});

and the code for the operationfilter

public class AuthorizationHeaderParameterOperationFilter : IOperationFilter
{
   public void Apply(Operation operation, OperationFilterContext context)
   {
      var filterPipeline = context.ApiDescription.ActionDescriptor.FilterDescriptors;
      var isAuthorized = filterPipeline.Select(filterInfo => filterInfo.Filter).Any(filter => filter is AuthorizeFilter);
      var allowAnonymous = filterPipeline.Select(filterInfo => filterInfo.Filter).Any(filter => filter is IAllowAnonymousFilter);

      if (isAuthorized && !allowAnonymous)
      {
          if (operation.Parameters == null)
             operation.Parameters = new List<IParameter>();

          operation.Parameters.Add(new NonBodyParameter
          {                    
             Name = "Authorization",
             In = "header",
             Description = "access token",
             Required = true,
             Type = "string"
         });
      }
   }
}

Then you will see an extra Authorization TextBox in your swagger where you can add your token in the format 'Bearer {jwttoken}' and you should be authorized in your swagger requests.