diff --git a/launcher/CMakeLists.txt b/launcher/CMakeLists.txt
index b5c52afa..0052f0e2 100644
--- a/launcher/CMakeLists.txt
+++ b/launcher/CMakeLists.txt
@@ -769,6 +769,8 @@ SET(LAUNCHER_SOURCES
     ui/dialogs/LoginDialog.h
     ui/dialogs/MSALoginDialog.cpp
     ui/dialogs/MSALoginDialog.h
+    ui/dialogs/OfflineLoginDialog.cpp
+    ui/dialogs/OfflineLoginDialog.h
     ui/dialogs/NewComponentDialog.cpp
     ui/dialogs/NewComponentDialog.h
     ui/dialogs/NewInstanceDialog.cpp
@@ -880,6 +882,7 @@ qt5_wrap_ui(LAUNCHER_UI
     ui/dialogs/ExportInstanceDialog.ui
     ui/dialogs/IconPickerDialog.ui
     ui/dialogs/MSALoginDialog.ui
+    ui/dialogs/OfflineLoginDialog.ui
     ui/dialogs/AboutDialog.ui
     ui/dialogs/LoginDialog.ui
     ui/dialogs/EditAccountDialog.ui
diff --git a/launcher/ui/dialogs/OfflineLoginDialog.cpp b/launcher/ui/dialogs/OfflineLoginDialog.cpp
new file mode 100644
index 00000000..f6ecc4e9
--- /dev/null
+++ b/launcher/ui/dialogs/OfflineLoginDialog.cpp
@@ -0,0 +1,113 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "OfflineLoginDialog.h"
+#include "ui_OfflineLoginDialog.h"
+
+#include "minecraft/auth/AccountTask.h"
+
+#include <QtWidgets/QPushButton>
+
+OfflineLoginDialog::OfflineLoginDialog(QWidget *parent) : QDialog(parent), ui(new Ui::OfflineLoginDialog)
+{
+    ui->setupUi(this);
+    ui->progressBar->setVisible(false);
+    ui->buttonBox->button(QDialogButtonBox::Ok)->setEnabled(false);
+
+    connect(ui->buttonBox, &QDialogButtonBox::accepted, this, &QDialog::accept);
+    connect(ui->buttonBox, &QDialogButtonBox::rejected, this, &QDialog::reject);
+}
+
+OfflineLoginDialog::~OfflineLoginDialog()
+{
+    delete ui;
+}
+
+// Stage 1: User interaction
+void OfflineLoginDialog::accept()
+{
+    setUserInputsEnabled(false);
+    ui->progressBar->setVisible(true);
+
+    // Setup the login task and start it
+    m_account = MinecraftAccount::createFromUsername(ui->userTextBox->text());
+    m_loginTask = m_account->login("TODO: create offline mode account flow");
+    connect(m_loginTask.get(), &Task::failed, this, &OfflineLoginDialog::onTaskFailed);
+    connect(m_loginTask.get(), &Task::succeeded, this, &OfflineLoginDialog::onTaskSucceeded);
+    connect(m_loginTask.get(), &Task::status, this, &OfflineLoginDialog::onTaskStatus);
+    connect(m_loginTask.get(), &Task::progress, this, &OfflineLoginDialog::onTaskProgress);
+    m_loginTask->start();
+}
+
+void OfflineLoginDialog::setUserInputsEnabled(bool enable)
+{
+    ui->userTextBox->setEnabled(enable);
+    ui->buttonBox->setEnabled(enable);
+}
+
+// Enable the OK button only when the textbox contains something.
+void OfflineLoginDialog::on_userTextBox_textEdited(const QString &newText)
+{
+    ui->buttonBox->button(QDialogButtonBox::Ok)
+        ->setEnabled(!newText.isEmpty());
+}
+
+void OfflineLoginDialog::onTaskFailed(const QString &reason)
+{
+    // Set message
+    auto lines = reason.split('\n');
+    QString processed;
+    for(auto line: lines) {
+        if(line.size()) {
+            processed += "<font color='red'>" + line + "</font><br />";
+        }
+        else {
+            processed += "<br />";
+        }
+    }
+    ui->label->setText(processed);
+
+    // Re-enable user-interaction
+    setUserInputsEnabled(true);
+    ui->progressBar->setVisible(false);
+}
+
+void OfflineLoginDialog::onTaskSucceeded()
+{
+    QDialog::accept();
+}
+
+void OfflineLoginDialog::onTaskStatus(const QString &status)
+{
+    ui->label->setText(status);
+}
+
+void OfflineLoginDialog::onTaskProgress(qint64 current, qint64 total)
+{
+    ui->progressBar->setMaximum(total);
+    ui->progressBar->setValue(current);
+}
+
+// Public interface
+MinecraftAccountPtr OfflineLoginDialog::newAccount(QWidget *parent, QString msg)
+{
+    OfflineLoginDialog dlg(parent);
+    dlg.ui->label->setText(msg);
+    if (dlg.exec() == QDialog::Accepted)
+    {
+        return dlg.m_account;
+    }
+    return 0;
+}
diff --git a/launcher/ui/dialogs/OfflineLoginDialog.h b/launcher/ui/dialogs/OfflineLoginDialog.h
new file mode 100644
index 00000000..ba0c1823
--- /dev/null
+++ b/launcher/ui/dialogs/OfflineLoginDialog.h
@@ -0,0 +1,58 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QtWidgets/QDialog>
+#include <QtCore/QEventLoop>
+
+#include "minecraft/auth/MinecraftAccount.h"
+#include "tasks/Task.h"
+
+namespace Ui
+{
+class OfflineLoginDialog;
+}
+
+class OfflineLoginDialog : public QDialog
+{
+    Q_OBJECT
+
+public:
+    ~OfflineLoginDialog();
+
+    static MinecraftAccountPtr newAccount(QWidget *parent, QString message);
+
+private:
+    explicit OfflineLoginDialog(QWidget *parent = 0);
+
+    void setUserInputsEnabled(bool enable);
+
+protected
+slots:
+    void accept();
+
+    void onTaskFailed(const QString &reason);
+    void onTaskSucceeded();
+    void onTaskStatus(const QString &status);
+    void onTaskProgress(qint64 current, qint64 total);
+
+    void on_userTextBox_textEdited(const QString &newText);
+
+private:
+    Ui::OfflineLoginDialog *ui;
+    MinecraftAccountPtr m_account;
+    Task::Ptr m_loginTask;
+};
diff --git a/launcher/ui/dialogs/OfflineLoginDialog.ui b/launcher/ui/dialogs/OfflineLoginDialog.ui
new file mode 100644
index 00000000..d8964a2e
--- /dev/null
+++ b/launcher/ui/dialogs/OfflineLoginDialog.ui
@@ -0,0 +1,67 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>OfflineLoginDialog</class>
+ <widget class="QDialog" name="OfflineLoginDialog">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>400</width>
+    <height>150</height>
+   </rect>
+  </property>
+  <property name="sizePolicy">
+   <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
+    <horstretch>0</horstretch>
+    <verstretch>0</verstretch>
+   </sizepolicy>
+  </property>
+  <property name="windowTitle">
+   <string>Add Account</string>
+  </property>
+  <layout class="QVBoxLayout" name="verticalLayout">
+   <item>
+    <widget class="QLabel" name="label">
+     <property name="text">
+      <string notr="true">Message label placeholder.</string>
+     </property>
+     <property name="textFormat">
+      <enum>Qt::RichText</enum>
+     </property>
+     <property name="textInteractionFlags">
+      <set>Qt::LinksAccessibleByKeyboard|Qt::LinksAccessibleByMouse|Qt::TextBrowserInteraction|Qt::TextSelectableByKeyboard|Qt::TextSelectableByMouse</set>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QLineEdit" name="userTextBox">
+     <property name="placeholderText">
+      <string>Username</string>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QProgressBar" name="progressBar">
+     <property name="value">
+      <number>69</number>
+     </property>
+     <property name="textVisible">
+      <bool>false</bool>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QDialogButtonBox" name="buttonBox">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+     <property name="standardButtons">
+      <set>QDialogButtonBox::Cancel|QDialogButtonBox::Ok</set>
+     </property>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <resources/>
+ <connections/>
+</ui>
diff --git a/launcher/ui/pages/global/AccountListPage.cpp b/launcher/ui/pages/global/AccountListPage.cpp
index b8da6c75..b9aa7628 100644
--- a/launcher/ui/pages/global/AccountListPage.cpp
+++ b/launcher/ui/pages/global/AccountListPage.cpp
@@ -24,6 +24,7 @@
 #include "net/NetJob.h"
 
 #include "ui/dialogs/ProgressDialog.h"
+#include "ui/dialogs/OfflineLoginDialog.h"
 #include "ui/dialogs/LoginDialog.h"
 #include "ui/dialogs/MSALoginDialog.h"
 #include "ui/dialogs/CustomMessageBox.h"
@@ -153,6 +154,22 @@ void AccountListPage::on_actionAddMicrosoft_triggered()
     }
 }
 
+void AccountListPage::on_actionAddOffline_triggered()
+{
+    MinecraftAccountPtr account = OfflineLoginDialog::newAccount(
+        this,
+        tr("Please enter your desired username to add your offline account.")
+    );
+
+    if (account)
+    {
+        m_accounts->addAccount(account);
+        if (m_accounts->count() == 1) {
+            m_accounts->setDefaultAccount(account);
+        }
+    }
+}
+
 void AccountListPage::on_actionRemove_triggered()
 {
     QModelIndexList selection = ui->listView->selectionModel()->selectedIndexes();
diff --git a/launcher/ui/pages/global/AccountListPage.h b/launcher/ui/pages/global/AccountListPage.h
index 1c65e708..841c3fd2 100644
--- a/launcher/ui/pages/global/AccountListPage.h
+++ b/launcher/ui/pages/global/AccountListPage.h
@@ -62,6 +62,7 @@ public:
 public slots:
     void on_actionAddMojang_triggered();
     void on_actionAddMicrosoft_triggered();
+    void on_actionAddOffline_triggered();
     void on_actionRemove_triggered();
     void on_actionRefresh_triggered();
     void on_actionSetDefault_triggered();
diff --git a/launcher/ui/pages/global/AccountListPage.ui b/launcher/ui/pages/global/AccountListPage.ui
index 29738c02..d21a92e2 100644
--- a/launcher/ui/pages/global/AccountListPage.ui
+++ b/launcher/ui/pages/global/AccountListPage.ui
@@ -54,6 +54,7 @@
    </attribute>
    <addaction name="actionAddMicrosoft"/>
    <addaction name="actionAddMojang"/>
+   <addaction name="actionAddOffline"/>
    <addaction name="actionRefresh"/>
    <addaction name="actionRemove"/>
    <addaction name="actionSetDefault"/>
@@ -103,6 +104,11 @@
     <string>Add Microsoft</string>
    </property>
   </action>
+  <action name="actionAddOffline">
+   <property name="text">
+    <string>Add Offline</string>
+   </property>
+  </action>
   <action name="actionRefresh">
    <property name="text">
     <string>Refresh</string>