diff --git a/app/decorators/current_user_decorator.rb b/app/decorators/current_user_decorator.rb
index 962f22b..4f8917f 100644
--- a/app/decorators/current_user_decorator.rb
+++ b/app/decorators/current_user_decorator.rb
@@ -1,7 +1,7 @@
 class CurrentUserDecorator < UserDecorator
 
   def display_name
-    model.username || model.email
+    model.username || model.email || model.temporary_username || "Me"
   end
 
 end
diff --git a/config/test.exs b/config/test.exs
index c0717b8..5a1e3cc 100644
--- a/config/test.exs
+++ b/config/test.exs
@@ -4,6 +4,7 @@ use Mix.Config
 # you can enable the server option below.
 config :asciinema, Asciinema.Endpoint,
   http: [port: 4001],
+  secret_key_base: "ssecretkeybasesecretkeybasesecretkeybasesecretkeybaseecretkeybase",
   server: false
 
 # Print only warnings and errors during test
diff --git a/docker/nginx/asciinema.conf b/docker/nginx/asciinema.conf
index 1a8b655..c333e8c 100644
--- a/docker/nginx/asciinema.conf
+++ b/docker/nginx/asciinema.conf
@@ -24,7 +24,7 @@ server {
 
     client_max_body_size 16m;
 
-    location ~ ^/(phoenix/|css/|js/|images/|fonts/|docs/?|api/asciicasts) {
+    location ~ ^/(phoenix/|css/|js/|images/|fonts/|docs/?|api/asciicasts|/connect/) {
         try_files /maintenance.html $uri/index.html $uri.html $uri @phoenix;
     }
 
diff --git a/lib/asciinema/auth.ex b/lib/asciinema/auth.ex
index 00d2c92..7661f48 100644
--- a/lib/asciinema/auth.ex
+++ b/lib/asciinema/auth.ex
@@ -8,12 +8,21 @@ defmodule Asciinema.Auth do
     opts
   end
 
+  def call(%Plug.Conn{assigns: %{current_user: %User{}}} = conn, _opts) do
+    conn
+  end
   def call(conn, _opts) do
     user_id = get_session(conn, @user_key)
     user = user_id && Repo.get(User, user_id)
     assign(conn, :current_user, user)
   end
 
+  def login(conn, %User{id: id} = user) do
+    conn
+    |> put_session(@user_key, id)
+    |> assign(:current_user, user)
+  end
+
   def get_basic_auth(conn) do
     with ["Basic " <> auth] <- get_req_header(conn, "authorization"),
          auth = String.replace(auth, ~r/^%/, ""), # workaround for 1.3.0-1.4.0 client bug
diff --git a/lib/asciinema/users.ex b/lib/asciinema/users.ex
index bfaab45..fc689a9 100644
--- a/lib/asciinema/users.ex
+++ b/lib/asciinema/users.ex
@@ -1,5 +1,6 @@
 defmodule Asciinema.Users do
   import Ecto.Query, warn: false
+  import Ecto, only: [assoc: 2]
   alias Asciinema.{Repo, User, ApiToken}
 
   def authenticate(api_token) do
@@ -55,4 +56,17 @@ defmodule Asciinema.Users do
     |> ApiToken.revoke_changeset
     |> Repo.update!
   end
+
+  def merge!(dst_user, src_user) do
+    Repo.transaction(fn ->
+      asciicasts_q = from(assoc(src_user, :asciicasts))
+      Repo.update_all(asciicasts_q, set: [user_id: dst_user.id, updated_at: Timex.now])
+      api_tokens_q = from(assoc(src_user, :api_tokens))
+      Repo.update_all(api_tokens_q, set: [user_id: dst_user.id, updated_at: Timex.now])
+      expiring_tokens_q = from(assoc(src_user, :expiring_tokens))
+      Repo.delete_all(expiring_tokens_q)
+      Repo.delete!(src_user)
+      dst_user
+    end)
+  end
 end
diff --git a/test/controllers/session_controller_test.exs b/test/controllers/session_controller_test.exs
new file mode 100644
index 0000000..10256cb
--- /dev/null
+++ b/test/controllers/session_controller_test.exs
@@ -0,0 +1,104 @@
+defmodule Asciinema.SessionControllerTest do
+  use Asciinema.ConnCase
+  alias Asciinema.{Users, User, ApiToken}
+
+  @revoked_token "eb927b31-9ca3-4a6a-8a0c-dfba318e2e84"
+  @regular_user_token "c4ecd96a-9a16-464d-be6a-bc1f3c50c4ae"
+  @other_regular_user_token "b26c2fe0-603b-4b10-b0fa-f6ec85628831"
+  @tmp_user_token "863f6ae5-3f32-4ffc-8d47-284222d6225f"
+  @other_tmp_user_token "2eafaa20-80c8-47fc-b014-74072027edae"
+
+  setup %{conn: conn} do
+    %User{} = Users.get_user_with_api_token("revoked", @revoked_token)
+    @revoked_token |> Users.get_api_token! |> Users.revoke_api_token!
+
+    regular_user = fixture(:user)
+    ApiToken.create_changeset(regular_user, @regular_user_token) |> Repo.insert!
+
+    other_regular_user = fixture(:user, %{username: "other", email: "other@example.com"})
+    ApiToken.create_changeset(other_regular_user, @other_regular_user_token) |> Repo.insert!
+
+    %User{} = tmp_user = Users.get_user_with_api_token("tmp", @tmp_user_token)
+
+    %User{} = Users.get_user_with_api_token("other_tmp", @other_tmp_user_token)
+
+    {:ok, conn: conn, regular_user: regular_user, tmp_user: tmp_user}
+  end
+
+  test "invalid token", %{conn: conn} do
+    conn = get conn, "/connect/nopenope"
+    assert redirected_to(conn, 302) == "/"
+    assert get_rails_flash(conn, :alert) =~ ~r/invalid token/i
+  end
+
+  test "revoked token", %{conn: conn} do
+    conn = get conn, "/connect/#{@revoked_token}"
+    assert redirected_to(conn, 302) == "/"
+    assert get_rails_flash(conn, :alert) =~ ~r/been revoked/i
+  end
+
+  test "guest with tmp user token", %{conn: conn} do
+    conn = get conn, "/connect/#{@tmp_user_token}"
+    assert redirected_to(conn, 302) == "/user/edit"
+    assert get_rails_flash(conn, :notice) =~ ~r/welcome.+username.+email/i
+  end
+
+  test "guest with regular user token", %{conn: conn} do
+    conn = get conn, "/connect/#{@regular_user_token}"
+    assert redirected_to(conn, 302) == "/~test"
+    assert get_rails_flash(conn, :notice) =~ ~r/welcome back/i
+  end
+
+  test "tmp user with his own token", %{conn: conn, tmp_user: user} do
+    conn = login_as(conn, user)
+    conn = get conn, "/connect/#{@tmp_user_token}"
+    assert redirected_to(conn, 302) == "/user/edit"
+    assert get_rails_flash(conn, :notice)
+  end
+
+  test "tmp user with other tmp user token", %{conn: conn, tmp_user: user} do
+    conn = login_as(conn, user)
+    conn = get conn, "/connect/#{@other_tmp_user_token}"
+    assert redirected_to(conn, 302) == "/user/edit"
+    assert get_rails_flash(conn, :notice)
+  end
+
+  test "tmp user with other regular user token", %{conn: conn, tmp_user: user} do
+    conn = login_as(conn, user)
+    conn = get conn, "/connect/#{@regular_user_token}"
+    assert redirected_to(conn, 302) == "/~test"
+    assert get_rails_flash(conn, :notice)
+  end
+
+  test "regular user with other tmp user token", %{conn: conn, regular_user: user} do
+    conn = login_as(conn, user)
+    conn = get conn, "/connect/#{@tmp_user_token}"
+    assert redirected_to(conn, 302) == "/~test"
+    assert get_rails_flash(conn, :notice)
+  end
+
+  test "regular user with his own token", %{conn: conn, regular_user: user} do
+    conn = login_as(conn, user)
+    conn = get conn, "/connect/#{@regular_user_token}"
+    assert redirected_to(conn, 302) == "/~test"
+    assert get_rails_flash(conn, :notice)
+  end
+
+  test "regular user with other regular user token", %{conn: conn, regular_user: user} do
+    conn = login_as(conn, user)
+    conn = get conn, "/connect/#{@other_regular_user_token}"
+    assert redirected_to(conn, 302) == "/~test"
+    assert get_rails_flash(conn, :alert)
+  end
+
+  defp get_rails_flash(conn, key) do
+    conn
+    |> get_session(:flash)
+    |> get_in([:flashes, key])
+  end
+
+  defp login_as(conn, user) do
+    assign(conn, :current_user, user)
+  end
+
+end
diff --git a/test/support/fixtures.ex b/test/support/fixtures.ex
index 88c9d43..5146a5f 100644
--- a/test/support/fixtures.ex
+++ b/test/support/fixtures.ex
@@ -11,9 +11,10 @@ defmodule Asciinema.Fixtures do
                  content_type: "application/json"}
   end
 
-  def fixture(:user, _attrs) do
-    attrs = %{username: "test",
-              auth_token: "authy-auth-auth"}
+  def fixture(:user, attrs) do
+    attrs = Map.merge(%{username: "test",
+                        email: "test@example.com",
+                        auth_token: "authy-auth-auth"}, attrs)
     Repo.insert!(User.changeset(%User{}, attrs))
   end
 
diff --git a/web/controllers/session_controller.ex b/web/controllers/session_controller.ex
new file mode 100644
index 0000000..8965a6c
--- /dev/null
+++ b/web/controllers/session_controller.ex
@@ -0,0 +1,78 @@
+defmodule Asciinema.SessionController do
+  use Asciinema.Web, :controller
+  import Asciinema.UserView, only: [profile_path: 1]
+  alias Asciinema.{Auth, Users, User}
+
+  def create(conn, %{"api_token" => api_token}) do
+    case Users.authenticate(api_token) do
+      {:ok, user} ->
+        login(conn, user)
+      {:error, :token_not_found} ->
+        conn
+        |> put_rails_flash(:alert, "Invalid token. Make sure you pasted the URL correctly.")
+        |> redirect(to: "/")
+      {:error, :token_revoked} ->
+        conn
+        |> put_rails_flash(:alert, "This token has been revoked.")
+        |> redirect(to: "/")
+    end
+  end
+
+  defp login(conn, logging_user) do
+    current_user = conn.assigns.current_user
+
+    case {current_user, logging_user} do
+      {nil, %User{email: nil}} ->
+        conn
+        |> Auth.login(logging_user)
+        |> put_rails_flash(:notice, "Welcome! Setting username and email will help you with logging in later.")
+        |> redirect_to_edit_profile
+      {nil, %User{}} ->
+        conn
+        |> Auth.login(logging_user)
+        |> put_rails_flash(:notice, "Welcome back!")
+        |> redirect_to_profile
+      {%User{id: id, email: nil}, %User{id: id}} ->
+        conn
+        |> put_rails_flash(:notice, "Setting username and email will help you with logging in later.")
+        |> redirect_to_edit_profile
+      {%User{email: nil}, %User{email: nil}} ->
+        Users.merge!(current_user, logging_user)
+        conn
+        |> put_rails_flash(:notice, "Setting username and email will help you with logging in later.")
+        |> redirect_to_edit_profile
+      {%User{email: nil}, %User{}} ->
+        Users.merge!(logging_user, current_user)
+        conn
+        |> Auth.login(logging_user)
+        |> put_rails_flash(:notice, "Recorder token has been added to your account.")
+        |> redirect_to_profile
+      {%User{}, %User{email: nil}} ->
+        Users.merge!(current_user, logging_user)
+        conn
+        |> put_rails_flash(:notice, "Recorder token has been added to your account.")
+        |> redirect_to_profile
+      {%User{id: id}, %User{id: id}} ->
+        conn
+        |> put_rails_flash(:notice, "You're already logged in.")
+        |> redirect_to_profile
+      {%User{}, %User{}} ->
+        conn
+        |> put_rails_flash(:alert, "This recorder token belongs to a different user.")
+        |> redirect_to_profile
+        # TODO offer merging
+    end
+  end
+
+  defp put_rails_flash(conn, key, value) do
+    put_session(conn, :flash, %{discard: [], flashes: %{key => value}})
+  end
+
+  defp redirect_to_profile(conn) do
+    redirect(conn, to: profile_path(conn.assigns.current_user))
+  end
+
+  defp redirect_to_edit_profile(conn) do
+    redirect(conn, to: user_path(conn, :edit))
+  end
+end
diff --git a/web/models/expiring_token.ex b/web/models/expiring_token.ex
new file mode 100644
index 0000000..0038f65
--- /dev/null
+++ b/web/models/expiring_token.ex
@@ -0,0 +1,7 @@
+defmodule Asciinema.ExpiringToken do
+  use Asciinema.Web, :model
+
+  schema "expiring_tokens" do
+    belongs_to :user, Asciinema.User
+  end
+end
diff --git a/web/models/user.ex b/web/models/user.ex
index 270af52..e87d6ff 100644
--- a/web/models/user.ex
+++ b/web/models/user.ex
@@ -14,6 +14,8 @@ defmodule Asciinema.User do
     timestamps(inserted_at: :created_at)
 
     has_many :asciicasts, Asciinema.Asciicast
+    has_many :api_tokens, Asciinema.ApiToken
+    has_many :expiring_tokens, Asciinema.ExpiringToken
   end
 
   @doc """
diff --git a/web/router.ex b/web/router.ex
index f248394..40ce858 100644
--- a/web/router.ex
+++ b/web/router.ex
@@ -50,6 +50,8 @@ defmodule Asciinema.Router do
 
     get "/docs", DocController, :index
     get "/docs/:topic", DocController, :show
+
+    get "/connect/:api_token", SessionController, :create
   end
 
   scope "/api", Asciinema.Api, as: :api do
@@ -65,6 +67,10 @@ end
 defmodule Asciinema.Router.Helpers.Extra do
   alias Asciinema.Router.Helpers, as: H
 
+  def user_path(_conn, :edit) do
+    "/user/edit"
+  end
+
   def asciicast_file_download_path(conn, asciicast) do
     H.asciicast_file_path(conn, :show, asciicast)
     |> String.replace_suffix("/json", ".json")