diff --git a/androidprojectmodifier.cpp b/androidprojectmodifier.cpp
index 60da22f..f53951f 100644
--- a/androidprojectmodifier.cpp
+++ b/androidprojectmodifier.cpp
@@ -123,8 +123,7 @@ QString AndroidProjectModifier::randomString(int length)
     const auto possibleCharacters = QStringLiteral("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789");
 
     QString randomString;
-    for(int i = 0; i < length; ++i)
-    {
+    for(int i = 0; i < length; ++i) {
        int index = qrand() % possibleCharacters.length();
        QChar nextChar = possibleCharacters.at(index);
        randomString.append(nextChar);
@@ -147,7 +146,7 @@ QString AndroidProjectModifier::resizeImage(const QHash<QString, QString> imageD
     convert.waitForFinished();
 
     if (convert.exitCode() != 0) {
-        throw QString("Warning: could not resize the image. Do you have the 'convert' utility installed?");
+        throw QString("Error: could not resize the image. Do you have the 'convert' utility installed?");
     }
 
     return tmpFile.fileName();
diff --git a/main.cpp b/main.cpp
index 953a3ef..572bd71 100644
--- a/main.cpp
+++ b/main.cpp
@@ -1,4 +1,5 @@
 #include <QCoreApplication>
+#include <QScopedPointer>
 
 #include "inputoutput.h"
 #include "githelper.h"
@@ -15,21 +16,31 @@ int main(int argc, char *argv[])
         if (app.arguments().count() < 4 || app.arguments().contains("--help")) {
             const auto binaryName = app.arguments().at(0);
 
-            io.writeError("Usage: " + binaryName + " androidPackageName pwaUrl outputPath [--manifest path-to-manifest]");
+            io.writeError("Usage: " + binaryName + " androidPackageName pwaUrl outputPath [--manifest path-to-manifest] [--local-manifest path-to-manifest]");
             io.writeError("Example: " + binaryName + " com.vendor.pwa https://pwa.vendor.com ./my-cool-pwa");
             io.writeError("Example: " + binaryName + " com.vendor.pwa https://pwa.vendor.com ./my-cool-pwa --manifest relative/path/to/manifest");
+            io.writeError("Example: " + binaryName + " com.vendor.pwa https://pwa.vendor.com ./my-cool-pwa --local-manifest ./manifest.json");
             return app.arguments().contains("--help") ? 0 : 1;
         }
 
         QString manifestPath;
+        QFile *localManifestFile = nullptr;
 
         if (app.arguments().contains("--manifest")) {
             auto index = app.arguments().indexOf("--manifest") + 1;
             if (app.arguments().count() <= index) {
-                qCritical() << "You must set a value for --manifest";
-                return 1;
+                throw QString("You must set a value for --manifest");
             }
             manifestPath = app.arguments().at(index);
+        } else if (app.arguments().contains("--local-manifest")) {
+            auto index = app.arguments().indexOf("--local-manifest") + 1;
+            if (app.arguments().count() <= index) {
+                throw QString("You must set a value for --local-manifest");
+            }
+            localManifestFile = new QFile(app.arguments().at(index), &app);
+            if (!localManifestFile->exists()) {
+                throw QString("The specified local manifest file does not exist");
+            }
         }
 
         auto url = app.arguments().at(2);
@@ -42,11 +53,15 @@ int main(int argc, char *argv[])
         gitHelper.checkout(outputDirectory);
         gitHelper.reinitGitDirectory(outputDirectory);
 
-        WebsiteParser parser(url, manifestPath);
+        QScopedPointer<WebsiteParser> parser(
+                    localManifestFile == nullptr
+                    ? new WebsiteParser(url, manifestPath)
+                    : new WebsiteParser(url, *localManifestFile)
+        );
 
-        auto basicData = parser.getData();
+        auto basicData = parser->getData();
         basicData.insert("package", packageName);
-        auto icons = parser.getImages();
+        auto icons = parser->getImages();
 
         AndroidProjectModifier androidProject(outputDirectory);
         androidProject.addSupportLibrary();
diff --git a/websiteparser.cpp b/websiteparser.cpp
index cb9fec9..4f8cd16 100644
--- a/websiteparser.cpp
+++ b/websiteparser.cpp
@@ -6,6 +6,19 @@ WebsiteParser::WebsiteParser(QString url, QString manifestPath)
     m_manifestPath = manifestPath;
 }
 
+WebsiteParser::WebsiteParser(QString url, QFile &manifestFile)
+{
+    m_url.setUrl(url);
+    m_manifestFile = &manifestFile;
+}
+
+WebsiteParser::~WebsiteParser()
+{
+    if (m_manifestFile != nullptr) {
+        delete m_manifestFile;
+    }
+}
+
 const QString WebsiteParser::getWebsiteContent()
 {
     if(!m_websiteContent.isNull() && !m_websiteContent.isEmpty()) {
@@ -60,27 +73,47 @@ const QString WebsiteParser::getManifestUrl()
 
 const QJsonDocument WebsiteParser::getManifestContent()
 {
-    if(m_manifestContent.isNull() || m_manifestContent.isEmpty()) {
-        QUrl manifestUrl = getManifestUrl();
+    if (m_manifestContent.isNull() || m_manifestContent.isEmpty()) {
+        if (m_manifestFile == nullptr) {
+            m_manifestContent = getDownloadedManifestContent();
+        } else {
+            m_manifestContent = getLocalManifestContent();
+        }
+    }
 
-        QNetworkAccessManager networkManager;
-        QNetworkRequest request(manifestUrl);
-        QEventLoop loop;
+    return QJsonDocument::fromJson(m_manifestContent.toUtf8());
+}
 
-        QObject::connect(&networkManager, &QNetworkAccessManager::finished, &loop, &QEventLoop::quit);
+const QString WebsiteParser::getDownloadedManifestContent()
+{
+    QUrl manifestUrl = getManifestUrl();
 
-        auto reply = networkManager.get(request);
+    QNetworkAccessManager networkManager;
+    QNetworkRequest request(manifestUrl);
+    QEventLoop loop;
 
-        loop.exec();
+    QObject::connect(&networkManager, &QNetworkAccessManager::finished, &loop, &QEventLoop::quit);
 
-        QString response = reply->readAll();
+    auto reply = networkManager.get(request);
 
-        delete reply;
+    loop.exec();
 
-        m_manifestContent = response;
+    QString response = reply->readAll();
+
+    delete reply;
+
+    return response.toUtf8();
+}
+
+const QString WebsiteParser::getLocalManifestContent()
+{
+    if (!m_manifestFile->open(QIODevice::ReadOnly)) {
+        throw QString("Could not open local manifest file for writing");
     }
+    auto result = m_manifestFile->readAll();
+    m_manifestFile->close();
 
-    return QJsonDocument::fromJson(m_manifestContent.toUtf8());
+    return result;
 }
 
 const QHash<QString, QString> WebsiteParser::getData()
diff --git a/websiteparser.h b/websiteparser.h
index af2c8a0..6524899 100644
--- a/websiteparser.h
+++ b/websiteparser.h
@@ -2,6 +2,7 @@
 #define WEBSITEPARSER_H
 
 #include <memory>
+#include <QFile>
 #include <QString>
 #include <QNetworkAccessManager>
 #include <QNetworkRequest>
@@ -17,6 +18,8 @@ class WebsiteParser
 {
 public:
     WebsiteParser(QString url, QString manifestPath);
+    WebsiteParser(QString url, QFile &manifestFile);
+    ~WebsiteParser();
 
     const QHash<QString, QString> getData();
     const QList<QHash<QString, QString>> getImages();
@@ -26,11 +29,14 @@ class WebsiteParser
     const QString getWebsiteContent();
     const QString getManifestUrl();
     const QJsonDocument getManifestContent();
+    const QString getDownloadedManifestContent();
+    const QString getLocalManifestContent();
 
     QString m_websiteContent;
     QString m_manifestContent;
     QString m_manifestPath;
     QUrl m_url;
+    QFile *m_manifestFile = nullptr;
 };
 
 #endif // WEBSITEPARSER_H