diff --git a/app/src/main/java/org/fdroid/fdroid/net/BluetoothDownloader.java b/app/src/main/java/org/fdroid/fdroid/net/BluetoothDownloader.java
index 63c125f44..c782d3ee6 100644
--- a/app/src/main/java/org/fdroid/fdroid/net/BluetoothDownloader.java
+++ b/app/src/main/java/org/fdroid/fdroid/net/BluetoothDownloader.java
@@ -80,7 +80,7 @@ public class BluetoothDownloader extends Downloader {
 
     @Override
     public void download() throws IOException, InterruptedException {
-        downloadFromStream(1024);
+        downloadFromStream(1024, false);
         connection.closeQuietly();
     }
 
diff --git a/app/src/main/java/org/fdroid/fdroid/net/Downloader.java b/app/src/main/java/org/fdroid/fdroid/net/Downloader.java
index 8be443376..ab5474ffb 100644
--- a/app/src/main/java/org/fdroid/fdroid/net/Downloader.java
+++ b/app/src/main/java/org/fdroid/fdroid/net/Downloader.java
@@ -31,8 +31,6 @@ public abstract class Downloader {
     private volatile int totalBytes;
     private Timer timer;
 
-    private final OutputStream outputStream;
-
     public final File outputFile;
 
     protected final URL sourceUrl;
@@ -60,7 +58,6 @@ public abstract class Downloader {
             throws FileNotFoundException, MalformedURLException {
         this.sourceUrl = url;
         outputFile = destFile;
-        outputStream = new FileOutputStream(outputFile);
     }
 
     public final InputStream getInputStream() throws IOException {
@@ -100,9 +97,10 @@ public abstract class Downloader {
 
     public abstract boolean isCached();
 
-    protected void downloadFromStream(int bufferSize) throws IOException, InterruptedException {
+    protected void downloadFromStream(int bufferSize, boolean resumable) throws IOException, InterruptedException {
         Utils.debugLog(TAG, "Downloading from stream");
         InputStream input = null;
+        OutputStream outputStream = new FileOutputStream(outputFile, resumable);
         try {
             input = getInputStream();
 
@@ -110,7 +108,7 @@ public abstract class Downloader {
             // we were interrupted before proceeding to the download.
             throwExceptionIfInterrupted();
 
-            copyInputToOutputStream(input, bufferSize);
+            copyInputToOutputStream(input, bufferSize, outputStream);
         } finally {
             Utils.closeQuietly(outputStream);
             Utils.closeQuietly(input);
@@ -126,6 +124,7 @@ public abstract class Downloader {
      * interrupt occured during that blocking operation. The goal is to ensure we
      * don't move onto another slow, network operation if we have cancelled the
      * download.
+     *
      * @throws InterruptedException
      */
     private void throwExceptionIfInterrupted() throws InterruptedException {
@@ -150,7 +149,7 @@ public abstract class Downloader {
      * keeping track of the number of bytes that have flowed through for the
      * progress counter.
      */
-    private void copyInputToOutputStream(InputStream input, int bufferSize) throws IOException, InterruptedException {
+    private void copyInputToOutputStream(InputStream input, int bufferSize, OutputStream output) throws IOException, InterruptedException {
         bytesRead = 0;
         totalBytes = totalDownloadSize();
         byte[] buffer = new byte[bufferSize];
@@ -178,14 +177,13 @@ public abstract class Downloader {
                 Utils.debugLog(TAG, "Finished downloading from stream");
                 break;
             }
-
             bytesRead += count;
-            outputStream.write(buffer, 0, count);
+            output.write(buffer, 0, count);
         }
         timer.cancel();
         timer.purge();
-        outputStream.flush();
-        outputStream.close();
+        output.flush();
+        output.close();
     }
 
     /**
diff --git a/app/src/main/java/org/fdroid/fdroid/net/HttpDownloader.java b/app/src/main/java/org/fdroid/fdroid/net/HttpDownloader.java
index 20dc237f2..f6a41c4fd 100644
--- a/app/src/main/java/org/fdroid/fdroid/net/HttpDownloader.java
+++ b/app/src/main/java/org/fdroid/fdroid/net/HttpDownloader.java
@@ -2,6 +2,7 @@ package org.fdroid.fdroid.net;
 
 import com.nostra13.universalimageloader.core.download.BaseImageDownloader;
 
+import org.apache.commons.io.FileUtils;
 import org.fdroid.fdroid.FDroidApp;
 import org.fdroid.fdroid.Utils;
 import org.spongycastle.util.encoders.Base64;
@@ -65,7 +66,7 @@ public class HttpDownloader extends Downloader {
      */
     @Override
     protected InputStream getDownloadersInputStream() throws IOException {
-        setupConnection();
+        setupConnection(false);
         return new BufferedInputStream(connection.getInputStream());
     }
 
@@ -79,8 +80,25 @@ public class HttpDownloader extends Downloader {
      */
     @Override
     public void download() throws IOException, InterruptedException {
-        setupConnection();
-        doDownload();
+        boolean resumable = false;
+        long fileLength = outputFile.length();
+
+        // get the file size from the server
+        HttpURLConnection tmpConn = getConnection();
+        int contentLength = -1;
+        if (tmpConn.getResponseCode() == 200) {
+            contentLength = tmpConn.getContentLength();
+        }
+        tmpConn.disconnect();
+        if (fileLength > contentLength) {
+            FileUtils.deleteQuietly(outputFile);
+        } else if (fileLength == contentLength && outputFile.isFile()) {
+            return; // already have it!
+        } else if (fileLength > 0) {
+            resumable = true;
+        }
+        setupConnection(resumable);
+        doDownload(resumable);
     }
 
     private boolean isSwapUrl() {
@@ -90,10 +108,8 @@ public class HttpDownloader extends Downloader {
                 && FDroidApp.subnetInfo.isInRange(host); // on the same subnet as we are
     }
 
-    protected void setupConnection() throws IOException {
-        if (connection != null) {
-            return;
-        }
+    private HttpURLConnection getConnection() throws IOException {
+        HttpURLConnection connection;
         if (isSwapUrl()) {
             // swap never works with a proxy, its unrouted IP on the same subnet
             connection = (HttpURLConnection) sourceUrl.openConnection();
@@ -113,9 +129,25 @@ public class HttpDownloader extends Downloader {
             String authString = username + ":" + password;
             connection.setRequestProperty("Authorization", "Basic " + Base64.toBase64String(authString.getBytes()));
         }
+        return connection;
     }
 
-    protected void doDownload() throws IOException, InterruptedException {
+    /**
+     * @return Whether the connection is resumable or not
+     */
+    protected void setupConnection(boolean resumable) throws IOException {
+        if (connection != null) {
+            return;
+        }
+        connection = getConnection();
+
+        if (resumable) {
+            // partial file exists, resume the download
+            connection.setRequestProperty("Range", "bytes=" + outputFile.length() + "-");
+        }
+    }
+
+    protected void doDownload(boolean resumable) throws IOException, InterruptedException {
         if (wantToCheckCache()) {
             setupCacheCheck();
             Utils.debugLog(TAG, "Checking cached status of " + sourceUrl);
@@ -125,8 +157,8 @@ public class HttpDownloader extends Downloader {
         if (isCached()) {
             Utils.debugLog(TAG, sourceUrl + " is cached, so not downloading (HTTP " + statusCode + ")");
         } else {
-            Utils.debugLog(TAG, "Downloading from " + sourceUrl);
-            downloadFromStream(4096);
+            Utils.debugLog(TAG, "doDownload for " + sourceUrl + " " + resumable);
+            downloadFromStream(8192, resumable);
             updateCacheCheck();
         }
     }
@@ -166,6 +198,8 @@ public class HttpDownloader extends Downloader {
 
     @Override
     public void close() {
-        connection.disconnect();
+        if (connection != null) {
+            connection.disconnect();
+        }
     }
 }
diff --git a/app/src/main/java/org/fdroid/fdroid/net/LocalFileDownloader.java b/app/src/main/java/org/fdroid/fdroid/net/LocalFileDownloader.java
index 7e249040e..2207a689f 100644
--- a/app/src/main/java/org/fdroid/fdroid/net/LocalFileDownloader.java
+++ b/app/src/main/java/org/fdroid/fdroid/net/LocalFileDownloader.java
@@ -43,7 +43,7 @@ public class LocalFileDownloader extends Downloader {
 
     @Override
     public void download() throws IOException, InterruptedException {
-        downloadFromStream(1024 * 50);
+        downloadFromStream(1024 * 50, false);
     }
 
     @Override