diff --git a/include/openspace/util/httprequest.h b/include/openspace/util/httprequest.h
index bdceebc341..52e59d1d91 100644
--- a/include/openspace/util/httprequest.h
+++ b/include/openspace/util/httprequest.h
@@ -35,6 +35,7 @@
 #include <vector>
 #include <mutex>
 #include <atomic>
+#include <thread>
 
 namespace openspace {
     
@@ -125,6 +126,7 @@ private:
 class HttpDownload {
 public:
     HttpDownload();
+    virtual ~HttpDownload() = default;
     using ProgressCallback = std::function<bool(HttpRequest::Progress)>;
     void onProgress(ProgressCallback progressCallback);
     bool hasStarted();
@@ -151,6 +153,7 @@ private:
 class SyncHttpDownload : public virtual HttpDownload {
 public:
     SyncHttpDownload(std::string url);
+    virtual ~SyncHttpDownload() = default;
     void download(HttpRequest::RequestOptions opt);
 protected:
     HttpRequest _httpRequest;
@@ -176,6 +179,7 @@ private:
 class HttpFileDownload : public virtual HttpDownload {
 public:
     HttpFileDownload(std::string destination);
+    virtual ~HttpFileDownload() = default;
 protected:
     bool initDownload() override;
     bool deinitDownload() override;
@@ -187,6 +191,7 @@ private:
 
 class HttpMemoryDownload : public virtual HttpDownload {
 public:
+    virtual ~HttpMemoryDownload() = default;
     const std::vector<char>& downloadedData();
 protected:
     bool initDownload() override;
@@ -200,6 +205,7 @@ private:
 class SyncHttpMemoryDownload : public SyncHttpDownload, public HttpMemoryDownload {
 public:
     SyncHttpMemoryDownload(std::string url);
+    SyncHttpMemoryDownload(SyncHttpMemoryDownload&&);
     virtual ~SyncHttpMemoryDownload() = default;
 };
 
@@ -207,6 +213,7 @@ public:
 class SyncHttpFileDownload : public SyncHttpDownload, public HttpFileDownload {
 public:
     SyncHttpFileDownload(std::string url, std::string destinationPath);
+    SyncHttpFileDownload(SyncHttpFileDownload&&);
     virtual ~SyncHttpFileDownload() = default;
 };
 
@@ -214,6 +221,7 @@ public:
 class AsyncHttpMemoryDownload : public AsyncHttpDownload, public HttpMemoryDownload {
 public:
     AsyncHttpMemoryDownload(std::string url);
+    AsyncHttpMemoryDownload(AsyncHttpMemoryDownload&&);
     virtual ~AsyncHttpMemoryDownload() = default;
 };
 
@@ -221,6 +229,7 @@ public:
 class AsyncHttpFileDownload : public AsyncHttpDownload, public HttpFileDownload {
 public:
     AsyncHttpFileDownload(std::string url, std::string destinationPath);
+    AsyncHttpFileDownload(AsyncHttpFileDownload&&);
     virtual ~AsyncHttpFileDownload() = default;
 };
 
diff --git a/include/openspace/util/resourcesynchronization.h b/include/openspace/util/resourcesynchronization.h
index e14d70be2e..eed9d1c1ef 100644
--- a/include/openspace/util/resourcesynchronization.h
+++ b/include/openspace/util/resourcesynchronization.h
@@ -53,19 +53,21 @@ public:
     virtual void cancel() = 0;
     virtual void clear() = 0;
 
-    virtual float nSynchronizedBytes() = 0;
-    virtual float nTotalBytes() = 0;
+    virtual size_t nSynchronizedBytes() = 0;
+    virtual size_t nTotalBytes() = 0;
     virtual bool nTotalBytesIsKnown() = 0;
     virtual float progress();
 
     void wait();
     bool isResolved();
     void resolve();
+    void reject();
     void updateProgress(float t);
 
 private:
     std::atomic<bool> _started;
     std::atomic<bool> _resolved;
+    std::atomic<bool> _rejected;
 };
 
 
diff --git a/modules/sync/syncs/httpsynchronization.cpp b/modules/sync/syncs/httpsynchronization.cpp
index d29dae1734..105754e948 100644
--- a/modules/sync/syncs/httpsynchronization.cpp
+++ b/modules/sync/syncs/httpsynchronization.cpp
@@ -36,6 +36,7 @@
 
 #include <sstream>
 #include <fstream>
+#include <numeric>
 
 namespace {
     const char* _loggerCat = "HttpSynchronization";
@@ -116,11 +117,12 @@ void HttpSynchronization::start() {
     _syncThread = std::thread([this, listUrls] {
         for (const auto& url : listUrls) {
             if (trySyncFromUrl(url)) {
+                createSyncFile();
                 resolve();
                 return;
             }
         }
-        //fail();
+        reject();
     });
 }
 
@@ -153,7 +155,7 @@ bool HttpSynchronization::trySyncFromUrl(std::string listUrl) {
     opt.requestTimeoutSeconds = 0;
 
     SyncHttpMemoryDownload fileListDownload(listUrl);
-    fileListDownload.onProgress([this](HttpRequest::Progress p) {
+    fileListDownload.onProgress([this](HttpRequest::Progress) {
         return !_shouldCancel;
     });
     fileListDownload.download(opt);
@@ -164,10 +166,21 @@ bool HttpSynchronization::trySyncFromUrl(std::string listUrl) {
 
     const std::vector<char>& buffer = fileListDownload.downloadedData();
 
+    _nSynchronizedBytes = 0;
+    _nTotalBytes = 0;
+    _nTotalBytesKnown = false;
+    
     std::istringstream fileList(std::string(buffer.begin(), buffer.end()));
 
-    std::vector<std::thread> downloadThreads;
     std::string line = "";
+
+    std::unordered_map<std::string, size_t> fileSizes;
+    std::mutex fileSizeMutex;
+    std::atomic_bool startedAllDownloads = false;
+    std::atomic_size_t nDownloads = 0;
+    
+    std::vector<AsyncHttpFileDownload> downloads;
+    
     while (fileList >> line) {
         size_t lastSlash = line.find_last_of('/');
         std::string filename = line.substr(lastSlash + 1);
@@ -175,19 +188,43 @@ bool HttpSynchronization::trySyncFromUrl(std::string listUrl) {
         std::string fileDestination = directory() +
         ghoul::filesystem::FileSystem::PathSeparator +
         filename;
-
-        std::thread t([opt, line, fileDestination]() {
-            SyncHttpFileDownload fileDownload(line, fileDestination);
-            fileDownload.download(opt);
+        
+        downloads.push_back(AsyncHttpFileDownload(line, fileDestination));
+        AsyncHttpFileDownload& fileDownload = downloads.back();
+        
+        bool reportedFileSize = false;
+        ++nDownloads;
+        
+        fileDownload.onProgress(
+            [this, line, &reportedFileSize, &fileSizes, &fileSizeMutex,
+             &startedAllDownloads, &nDownloads](HttpRequest::Progress p)
+        {
+            if (!reportedFileSize && p.totalBytesKnown) {
+                std::lock_guard<std::mutex> guard(fileSizeMutex);
+                fileSizes[line] = p.totalBytes;
+                reportedFileSize = true;
+                
+                if (!_nTotalBytesKnown && startedAllDownloads && fileSizes.size() == nDownloads) {
+                    _nTotalBytesKnown = true;
+                    _nTotalBytes = std::accumulate(fileSizes.begin(), fileSizes.end(), size_t(0),
+                        [](size_t a, auto b) {
+                        return a + b.second;
+                    });
+                }
+            }
+            return !_shouldCancel;
         });
-        downloadThreads.push_back(std::move(t));
-    }
 
-    for (auto& t : downloadThreads) {
-        t.join();
+        fileDownload.start(opt);
+    }
+    startedAllDownloads = true;
+    
+    for (auto& d : downloads) {
+        d.wait();
+        if (!d.hasSucceeded()) {
+            return false;
+        }
     }
-
-    createSyncFile();
     return true;
 }
 
@@ -200,11 +237,11 @@ void HttpSynchronization::createSyncFile() {
     syncFile.close();
 }
 
-float HttpSynchronization::nSynchronizedBytes() {
-    return 0;
+size_t HttpSynchronization::nSynchronizedBytes() {
+    return _nSynchronizedBytes;
 }
 
-float HttpSynchronization::nTotalBytes() {
+size_t HttpSynchronization::nTotalBytes() {
     return 0;
 }
 
diff --git a/modules/sync/syncs/httpsynchronization.h b/modules/sync/syncs/httpsynchronization.h
index 6680bc370b..76541c528d 100644
--- a/modules/sync/syncs/httpsynchronization.h
+++ b/modules/sync/syncs/httpsynchronization.h
@@ -46,8 +46,8 @@ public:
     void cancel() override;
     void clear() override;
 
-    float nSynchronizedBytes() override;
-    float nTotalBytes() override;
+    size_t nSynchronizedBytes() override;
+    size_t nTotalBytes() override;
     bool nTotalBytesIsKnown() override;
 
 private:
@@ -57,8 +57,8 @@ private:
     void createSyncFile();
 
     std::atomic_bool _nTotalBytesKnown;
-    std::atomic<float> _nTotalBytes;
-    std::atomic<float> _nSynchronizedBytes;
+    std::atomic_size_t _nTotalBytes;
+    std::atomic_size_t _nSynchronizedBytes;
 
     std::atomic_bool _shouldCancel;
     std::string _identifier;
diff --git a/modules/sync/syncs/torrentsynchronization.cpp b/modules/sync/syncs/torrentsynchronization.cpp
index f0d31d5401..f47985f257 100644
--- a/modules/sync/syncs/torrentsynchronization.cpp
+++ b/modules/sync/syncs/torrentsynchronization.cpp
@@ -123,11 +123,11 @@ void TorrentSynchronization::clear() {
 }
 
 
-float TorrentSynchronization::nSynchronizedBytes() {
+size_t TorrentSynchronization::nSynchronizedBytes() {
     return 0;
 }
 
-float TorrentSynchronization::nTotalBytes() {
+size_t TorrentSynchronization::nTotalBytes() {
     return 0;
 }
 
diff --git a/modules/sync/syncs/torrentsynchronization.h b/modules/sync/syncs/torrentsynchronization.h
index 108dfd7586..ac30b85d9f 100644
--- a/modules/sync/syncs/torrentsynchronization.h
+++ b/modules/sync/syncs/torrentsynchronization.h
@@ -49,8 +49,8 @@ public:
     void cancel() override;
     void clear() override;
 
-    float nSynchronizedBytes() override;
-    float nTotalBytes() override;
+    size_t nSynchronizedBytes() override;
+    size_t nTotalBytes() override;
     bool nTotalBytesIsKnown() override;
 
 private:
diff --git a/src/scene/assetsynchronizer.cpp b/src/scene/assetsynchronizer.cpp
index e55df21a5d..7add472e21 100644
--- a/src/scene/assetsynchronizer.cpp
+++ b/src/scene/assetsynchronizer.cpp
@@ -105,10 +105,10 @@ float AssetSynchronizer::assetProgress(Asset* asset) {
 
     for (const auto& sync : syncs) {
         if (sync->nTotalBytesIsKnown()) {
-            return 0;
-        } else {
             nTotalBytes += sync->nTotalBytes();
             nSyncedBytes += sync->nSynchronizedBytes();
+        } else {
+            return 0;
         }
     }
 
diff --git a/src/util/resourcesynchronization.cpp b/src/util/resourcesynchronization.cpp
index 8b8f8252ec..d72adce337 100644
--- a/src/util/resourcesynchronization.cpp
+++ b/src/util/resourcesynchronization.cpp
@@ -106,6 +106,10 @@ void ResourceSynchronization::resolve() {
     _resolved = true;
 }
 
+void ResourceSynchronization::reject() {
+    _rejected = true;
+}
+
 float ResourceSynchronization::progress() {
     if (!nTotalBytesIsKnown()) {
         return 0.f;