To apply JWT (JSON Web Token) access tokens and refresh tokens in an ASP .NET Core Web API, you can follow these steps: Install the necessary NuGet packages: dotnet add package Microsoft.AspNetCore.Authentication.JwtBearer dotnet add package Microsoft.AspNetCore.Authorization In the Startup.cs file, configure the JWT authentication scheme in the ConfigureServices method: services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme) .AddJwtBearer(options => { options.TokenValidationParameters = new TokenValidationParameters { ValidateIssuer = true, ValidateAudience = true, ValidateLifetime = true, ValidateIssuerSigningKey = true, ValidIssuer = Configuration["Jwt:Issuer"], ValidAudience = Configuration["Jwt:Audience"], IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(Configuration["Jwt:Key"])) }; }); In the Config...