diff --git a/src/Api/Controllers/AliveController.cs b/src/Api/Controllers/AliveController.cs
index 17914bd89..32936e658 100644
--- a/src/Api/Controllers/AliveController.cs
+++ b/src/Api/Controllers/AliveController.cs
@@ -1,5 +1,6 @@
 using System;
 using Microsoft.AspNetCore.Mvc;
+using System.Linq;
 
 namespace Bit.Api.Controllers
 {
@@ -11,5 +12,11 @@ namespace Bit.Api.Controllers
         {
             return DateTime.UtcNow;
         }
+
+        [HttpGet("claims")]
+        public IActionResult Claims()
+        {
+            return new JsonResult(User.Claims.Select(c => new { c.Type, c.Value }));
+        }
     }
 }
diff --git a/src/Api/Startup.cs b/src/Api/Startup.cs
index c81949554..40e4d5ece 100644
--- a/src/Api/Startup.cs
+++ b/src/Api/Startup.cs
@@ -25,6 +25,10 @@ using Microsoft.Net.Http.Headers;
 using Newtonsoft.Json.Serialization;
 using AspNetCoreRateLimit;
 using Bit.Api.Middleware;
+using IdentityServer4.Validation;
+using IdentityServer4.Services;
+using IdentityModel.AspNetCore.OAuth2Introspection;
+using Microsoft.AspNetCore.Authorization.Infrastructure;
 
 namespace Bit.Api
 {
@@ -81,6 +85,15 @@ namespace Bit.Api
             services.AddSingleton<IIpPolicyStore, MemoryCacheIpPolicyStore>();
             services.AddSingleton<IRateLimitCounterStore, MemoryCacheRateLimitCounterStore>();
 
+            // IdentityServer
+            services.AddIdentityServer()
+                // TODO: Add proper signing creds
+                .AddTemporarySigningCredential()
+                .AddInMemoryApiResources(Resources.GetApiResources())
+                .AddInMemoryClients(Clients.GetClients());
+            services.AddSingleton<IResourceOwnerPasswordValidator, ResourceOwnerPasswordValidator>();
+            services.AddSingleton<IProfileService, ProfileService>();
+
             // Identity
             services.AddTransient<ILookupNormalizer, LowerInvariantLookupNormalizer>();
             services.AddJwtBearerIdentity(options =>
@@ -121,13 +134,19 @@ namespace Bit.Api
             var jwtIdentityOptions = provider.GetRequiredService<IOptions<JwtBearerIdentityOptions>>().Value;
             services.AddAuthorization(config =>
             {
-                config.AddPolicy("Application", new AuthorizationPolicyBuilder()
-                    .AddAuthenticationSchemes(JwtBearerDefaults.AuthenticationScheme‌​)
-                    .RequireAuthenticatedUser().RequireClaim(ClaimTypes.AuthenticationMethod, jwtIdentityOptions.AuthenticationMethod).Build());
+                config.AddPolicy("Application", policy =>
+                {
+                    policy.AddAuthenticationSchemes(JwtBearerDefaults.AuthenticationScheme, "Bearer2");
+                    policy.RequireAuthenticatedUser();
+                    policy.RequireClaim(ClaimTypes.AuthenticationMethod, jwtIdentityOptions.AuthenticationMethod);
+                });
 
-                config.AddPolicy("TwoFactor", new AuthorizationPolicyBuilder()
-                    .AddAuthenticationSchemes(JwtBearerDefaults.AuthenticationScheme)
-                    .RequireAuthenticatedUser().RequireClaim(ClaimTypes.AuthenticationMethod, jwtIdentityOptions.TwoFactorAuthenticationMethod).Build());
+                config.AddPolicy("TwoFactor", policy =>
+                {
+                    policy.AddAuthenticationSchemes(JwtBearerDefaults.AuthenticationScheme, "Bearer2");
+                    policy.RequireAuthenticatedUser();
+                    policy.RequireClaim(ClaimTypes.AuthenticationMethod, jwtIdentityOptions.TwoFactorAuthenticationMethod);
+                });
             });
 
             services.AddScoped<AuthenticatorTokenProvider>();
@@ -207,6 +226,18 @@ namespace Bit.Api
             // Add Cors
             app.UseCors("All");
 
+            // Add IdentityServer to the request pipeline.
+            app.UseIdentityServer();
+            app.UseIdentityServerAuthentication(new IdentityServerAuthenticationOptions
+            {
+                AllowedScopes = new string[] { "api" },
+                Authority = env.IsProduction() ? "https://api.bitwarden.com" : "http://localhost:4000",
+                RequireHttpsMetadata = env.IsProduction(),
+                ApiName = "Vault API",
+                AuthenticationScheme = "Bearer2",
+                TokenRetriever = TokenRetrieval.FromAuthorizationHeader("Bearer2")
+            });
+
             // Add Jwt authentication to the request pipeline.
             app.UseJwtBearerIdentity();
 
diff --git a/src/Core/Identity/Clients.cs b/src/Core/Identity/Clients.cs
new file mode 100644
index 000000000..8669d4f49
--- /dev/null
+++ b/src/Core/Identity/Clients.cs
@@ -0,0 +1,31 @@
+using IdentityServer4.Models;
+using System.Collections.Generic;
+
+namespace Bit.Core.Identity
+{
+    public class Clients
+    {
+        public static IEnumerable<Client> GetClients()
+        {
+            return new List<Client>
+            {
+                new ApiClient("mobile"),
+                new ApiClient("web"),
+                new ApiClient("browser"),
+                new ApiClient("desktop")
+            };
+        }
+
+        public class ApiClient : Client
+        {
+            public ApiClient(string id)
+            {
+                ClientId = id;
+                RequireClientSecret = false;
+                AllowedGrantTypes = GrantTypes.ResourceOwnerPassword;
+                AllowOfflineAccess = true;
+                AllowedScopes = new string[] { "api" };
+            }
+        }
+    }
+}
diff --git a/src/Core/Identity/ProfileService.cs b/src/Core/Identity/ProfileService.cs
new file mode 100644
index 000000000..600fa1420
--- /dev/null
+++ b/src/Core/Identity/ProfileService.cs
@@ -0,0 +1,36 @@
+using IdentityServer4.Services;
+using System.Threading.Tasks;
+using IdentityServer4.Models;
+using Bit.Core.Repositories;
+using Bit.Core.Services;
+using System.Security.Claims;
+
+namespace Bit.Core.Identity
+{
+    public class ProfileService : IProfileService
+    {
+        private readonly IUserService _userService;
+        private readonly IUserRepository _userRepository;
+
+        public ProfileService(
+            IUserRepository userRepository,
+            IUserService userService)
+        {
+            _userRepository = userRepository;
+            _userService = userService;
+        }
+
+        public Task GetProfileDataAsync(ProfileDataRequestContext context)
+        {
+            // TODO: load proper claims for user
+            context.AddFilteredClaims(new Claim[] { new Claim(ClaimTypes.AuthenticationMethod, "Application") });
+            return Task.FromResult(0);
+        }
+
+        public Task IsActiveAsync(IsActiveContext context)
+        {
+            context.IsActive = true;
+            return Task.FromResult(0);
+        }
+    }
+}
diff --git a/src/Core/Identity/ResourceOwnerPasswordValidator.cs b/src/Core/Identity/ResourceOwnerPasswordValidator.cs
new file mode 100644
index 000000000..e121cb5d8
--- /dev/null
+++ b/src/Core/Identity/ResourceOwnerPasswordValidator.cs
@@ -0,0 +1,41 @@
+using Bit.Core.Domains;
+using Bit.Core.Repositories;
+using IdentityServer4.Models;
+using IdentityServer4.Validation;
+using Microsoft.AspNetCore.Identity;
+using System.Security.Claims;
+using System.Threading.Tasks;
+
+namespace Bit.Core.Identity
+{
+    public class ResourceOwnerPasswordValidator : IResourceOwnerPasswordValidator
+    {
+        private readonly IUserRepository _userRepository;
+        private readonly UserManager<User> _userManager;
+
+        public ResourceOwnerPasswordValidator(
+            IUserRepository userRepository,
+            UserManager<User> userManager)
+        {
+            _userRepository = userRepository;
+            _userManager = userManager;
+        }
+
+        public async Task ValidateAsync(ResourceOwnerPasswordValidationContext context)
+        {
+            var user = await _userRepository.GetByEmailAsync(context.UserName.ToLowerInvariant());
+            if(user != null)
+            {
+                if(await _userManager.CheckPasswordAsync(user, context.Password))
+                {
+                    // TODO: proper claims and auth method
+                    context.Result = new GrantValidationResult(subject: user.Id.ToString(), authenticationMethod: "Application",
+                         identityProvider: "bitwarden", claims: new Claim[] { new Claim(ClaimTypes.AuthenticationMethod, "Application") });
+                    return;
+                }
+            }
+
+            context.Result = new GrantValidationResult(TokenRequestErrors.InvalidGrant, "Username or password is incorrect.");
+        }
+    }
+}
diff --git a/src/Core/Identity/Resources.cs b/src/Core/Identity/Resources.cs
new file mode 100644
index 000000000..0ed65914b
--- /dev/null
+++ b/src/Core/Identity/Resources.cs
@@ -0,0 +1,17 @@
+using IdentityServer4.Models;
+using System.Collections.Generic;
+using System.Security.Claims;
+
+namespace Bit.Core.Identity
+{
+    public class Resources
+    {
+        public static IEnumerable<ApiResource> GetApiResources()
+        {
+            return new List<ApiResource>
+            {
+                new ApiResource("api", "Vault API", new string[] { ClaimTypes.AuthenticationMethod })
+            };
+        }
+    }
+}
diff --git a/src/Core/project.json b/src/Core/project.json
index 1cd5c35f0..7d6c38e7e 100644
--- a/src/Core/project.json
+++ b/src/Core/project.json
@@ -8,7 +8,9 @@
     "DataTableProxy": "1.2.0",
     "Sendgrid": "6.3.4",
     "PushSharp": "4.0.10",
-    "WindowsAzure.Storage": "8.0.0"
+    "WindowsAzure.Storage": "8.0.0",
+    "IdentityServer4": "1.0.1",
+    "IdentityServer4.AccessTokenValidation": "1.0.2"
   },
 
   "frameworks": {