diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 4c0296d6..9e397a6b 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -17,7 +17,7 @@ jobs:
     steps:
     - uses: actions/checkout@v4
     - name: Install Apt Dependencies
-      run: sudo apt update && sudo apt install ninja-build qtbase5-dev qttools5-dev libboost-dev libboost-date-time-dev libboost-iostreams-dev nlohmann-json3-dev libasound2-dev librtmidi-dev libminizip-dev doctest-dev
+      run: sudo apt update && sudo apt install ninja-build qtbase5-dev qttools5-dev libboost-dev libboost-date-time-dev libboost-iostreams-dev nlohmann-json3-dev libasound2-dev librtmidi-dev libminizip-dev doctest-dev libfmt-dev
     - name: Install Other Dependencies
       run: vcpkg install pugixml
     - name: Create Build Directory
@@ -44,7 +44,7 @@ jobs:
 
     - name: Install Dependencies
       # CMake 3.17 is already installed
-      run: brew install boost doctest minizip ninja nlohmann-json pugixml qt5 pugixml rtmidi
+      run: brew install boost doctest minizip ninja nlohmann-json pugixml qt5 pugixml rtmidi fmt
     - name: Generate Project
       run: cmake -S ${GITHUB_WORKSPACE} -B ${{runner.workspace}}/build -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH=/usr/local/opt/qt5/lib/cmake
     - name: Build
@@ -98,7 +98,7 @@ jobs:
       run: echo "::set-output name=VERSION_ID::$(git describe --tags --long --always)"
 
     - name: Install Dependencies
-      run: vcpkg install --triplet ${{ matrix.arch }}-windows boost-algorithm boost-date-time boost-endian boost-functional boost-iostreams boost-range boost-rational boost-signals2 boost-stacktrace doctest minizip nlohmann-json pugixml
+      run: vcpkg install --triplet ${{ matrix.arch }}-windows boost-algorithm boost-date-time boost-endian boost-functional boost-iostreams boost-range boost-rational boost-signals2 boost-stacktrace doctest minizip nlohmann-json pugixml fmt
 
     # Building Qt via vcpkg would take a while ...
     - name: Install Qt
diff --git a/README.md b/README.md
index c4991e74..49bf94be 100644
--- a/README.md
+++ b/README.md
@@ -82,9 +82,10 @@ Power Tab Editor 2.0 - A powerful cross platform guitar tablature viewer and edi
 * [pugixml](https://pugixml.org/)
 * [minizip](https://github.com/madler/zlib)
 * [doctest](https://github.com/onqtam/doctest)
+* [fmtlib](https://github.com/fmtlib/fmt)
 * (Linux only) - ALSA library (e.g. `libasound2-dev`)
 * (Linux only) - MIDI sequencer (e.g. `timidity-daemon`)
-* A compiler with C++17 support.
+* A compiler with C++20 support.
 
 ### Building:
 #### Windows:
diff --git a/cmake/PTE_ThirdParty.cmake b/cmake/PTE_ThirdParty.cmake
index ad5da565..c02c0bb0 100644
--- a/cmake/PTE_ThirdParty.cmake
+++ b/cmake/PTE_ThirdParty.cmake
@@ -11,3 +11,4 @@ include ( third_party/nlohmann_json )
 include ( third_party/pugixml )
 include ( third_party/Qt )
 include ( third_party/rtmidi )
+include ( third_party/fmt )
diff --git a/cmake/third_party/fmt.cmake b/cmake/third_party/fmt.cmake
new file mode 100644
index 00000000..31a2e99a
--- /dev/null
+++ b/cmake/third_party/fmt.cmake
@@ -0,0 +1 @@
+find_package ( fmt 8.0.0 REQUIRED )
diff --git a/source/app/CMakeLists.txt b/source/app/CMakeLists.txt
index 68de5d64..6a5cc02f 100644
--- a/source/app/CMakeLists.txt
+++ b/source/app/CMakeLists.txt
@@ -23,6 +23,7 @@ set( headers
     command.h
     documentmanager.h
     paths.h
+    log.h
     powertabeditor.h
     recentfiles.h
     scorearea.h
diff --git a/source/app/log.h b/source/app/log.h
new file mode 100644
index 00000000..50c39fad
--- /dev/null
+++ b/source/app/log.h
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2024 Simon Symeonidis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef APP_LOG_H
+#define APP_LOG_H
+
+#include <util/log.h>
+
+#include <QString>
+#include <fmt/core.h>
+#include <fmt/format.h>
+#include <string>
+
+/* Adapted from: https://fmt.dev/latest/api.html#udt */
+template <>
+struct fmt::formatter<QString> : fmt::formatter<std::string>
+{
+    auto format(const QString& qstr, fmt::format_context& ctx) const {
+        return fmt::formatter<std::string>::format(qstr.toStdString(), ctx);
+    }
+};
+
+#endif
diff --git a/source/app/paths.cpp b/source/app/paths.cpp
index 4d5bce2c..bbb9e0c8 100644
--- a/source/app/paths.cpp
+++ b/source/app/paths.cpp
@@ -39,6 +39,11 @@ path getConfigDir()
 #endif
 }
 
+path getLogPath()
+{
+    return getConfigDir() / "log.txt";
+}
+
 path getUserDataDir()
 {
     return fromQString(
diff --git a/source/app/paths.h b/source/app/paths.h
index 898a3ab4..e81bb6cf 100644
--- a/source/app/paths.h
+++ b/source/app/paths.h
@@ -26,6 +26,9 @@ namespace Paths {
     /// Return a path to a directory where config files should be written to.
     path getConfigDir();
 
+    /// Return a path to the log file
+    path getLogPath();
+
     /// Return a path to a directory where persistent application data should
     /// be written to.
     path getUserDataDir();
diff --git a/source/app/powertabeditor.cpp b/source/app/powertabeditor.cpp
index f6c952d2..b596bfb7 100644
--- a/source/app/powertabeditor.cpp
+++ b/source/app/powertabeditor.cpp
@@ -79,6 +79,7 @@
 #include <app/command.h>
 #include <app/documentmanager.h>
 #include <app/paths.h>
+#include <app/log.h>
 #include <app/recentfiles.h>
 #include <app/scorearea.h>
 #include <app/settings.h>
@@ -260,14 +261,14 @@ void PowerTabEditor::openFile(QString filename)
     int validationResult = myDocumentManager->findDocument(path);
     if (validationResult > -1)
     {
-        qDebug() << "File: " << filename << " is already open";
+        Log::d("file: {} is already open", filename);
         myTabWidget->setCurrentIndex(validationResult);
         return;
     }
 
     auto start = std::chrono::high_resolution_clock::now();
 
-    qDebug() << "Opening file: " << filename;
+    Log::d("opening file: {}", filename);
 
     QFileInfo fileInfo(filename);
     std::optional<FileFormat> format = myFileFormatManager->findFormat(
@@ -285,9 +286,8 @@ void PowerTabEditor::openFile(QString filename)
         Document &doc = myDocumentManager->addDocument(*mySettingsManager);
         myFileFormatManager->importFile(doc.getScore(), path, *format);
         auto end = std::chrono::high_resolution_clock::now();
-        qDebug() << "File loaded in"
-                 << std::chrono::duration_cast<std::chrono::milliseconds>(end - start) .count()
-                 << "ms";
+
+	Log::d("file loaded in: {}ms", std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count());
 
         doc.setFilename(path);
         setPreviousDirectory(filename);
@@ -3616,7 +3616,7 @@ void PowerTabEditor::setPreviousDirectory(const QString &fileName)
 void PowerTabEditor::setupNewTab()
 {
     auto start = std::chrono::high_resolution_clock::now();
-    qDebug() << "Tab creation started ...";
+    Log::d("tab creation started...");
 
     Q_ASSERT(myDocumentManager->hasOpenDocuments());
     Document &doc = myDocumentManager->getCurrentDocument();
@@ -3788,9 +3788,7 @@ void PowerTabEditor::setupNewTab()
     scorearea->setFocus();
 
     auto end = std::chrono::high_resolution_clock::now();
-    qDebug() << "Tab opened in"
-             << std::chrono::duration_cast<std::chrono::milliseconds>(
-                    end - start).count() << "ms";
+    Log::d("tab opened in: {}ms", std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count());
 }
 
 namespace
diff --git a/source/app/scorearea.cpp b/source/app/scorearea.cpp
index 4ae21258..3a9c6949 100644
--- a/source/app/scorearea.cpp
+++ b/source/app/scorearea.cpp
@@ -14,7 +14,7 @@
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
-  
+
 #include "scorearea.h"
 
 #include <app/documentmanager.h>
@@ -32,6 +32,7 @@
 #include <QPrinter>
 #include <QScrollBar>
 #include <score/score.h>
+#include <util/log.h>
 
 void ScoreArea::Scene::dragEnterEvent(QGraphicsSceneDragDropEvent *event)
 {
@@ -114,7 +115,7 @@ void ScoreArea::renderDocument(const Document &document)
 #endif
     std::vector<std::future<void>> tasks;
     const int work_size = myRenderedSystems.size() / num_threads;
-    qDebug() << "Using" << num_threads << "worker thread(s)";
+    Log::d("using {} worker thread(s)", num_threads);
 
     for (int i = 0; i < num_threads; ++i)
     {
@@ -162,10 +163,13 @@ void ScoreArea::renderDocument(const Document &document)
     myScene.setSceneRect(myScene.itemsBoundingRect());
 
     auto end = std::chrono::high_resolution_clock::now();
-    qDebug() << "Score rendered in"
-             << std::chrono::duration_cast<std::chrono::milliseconds>(
-                    end - start).count() << "ms";
-    qDebug() << "Rendered " << myScene.items().size() << "items";
+
+    namespace sc = std::chrono;
+    const auto time_elapsed = static_cast<long long int>
+        (sc::duration_cast<sc::milliseconds>(end - start).count());
+
+    Log::d("score rendered in {} ms", time_elapsed);
+    Log::d("rendered {} items", myScene.items().size());
 }
 
 void ScoreArea::redrawSystem(int index)
diff --git a/source/app/settingsmanager.cpp b/source/app/settingsmanager.cpp
index b1083223..be0f5bcc 100644
--- a/source/app/settingsmanager.cpp
+++ b/source/app/settingsmanager.cpp
@@ -17,6 +17,8 @@
 
 #include "settingsmanager.h"
 
+#include <util/log.h>
+
 #include <fstream>
 #include <iostream>
 
@@ -47,7 +49,7 @@ void SettingsManager::load(const std::filesystem::path &dir)
     }
     catch (const std::exception &e)
     {
-        std::cerr << "Error loading " << path << ": " << e.what() << std::endl;
+        Log::e("error loading {}: {}", path.generic_string(), e.what());
     }
 #endif
 }
diff --git a/source/app/tuningdictionary.cpp b/source/app/tuningdictionary.cpp
index 35b8be2e..284e876b 100644
--- a/source/app/tuningdictionary.cpp
+++ b/source/app/tuningdictionary.cpp
@@ -26,6 +26,7 @@
 #include <score/serialization.h>
 #include <stdexcept>
 #include <unordered_set>
+#include <util/log.h>
 
 static const char *theTuningDictFilename = "tunings.json";
 
@@ -70,11 +71,11 @@ TuningDictionary::load()
 
     if (entries.empty())
     {
-        std::cerr << "Could not locate tuning dictionary." << std::endl;
-        std::cerr << "Candidate paths:" << std::endl;
+        Log::e("could not locate tuning dictionary");
+        Log::e("candidate paths: ");
 
         for (std::filesystem::path dir : Paths::getDataDirs())
-            std::cerr << (dir / theTuningDictFilename) << std::endl;
+            Log::e(" - {}", (dir / theTuningDictFilename).generic_string());
     }
 
     return entries;
diff --git a/source/audio/midioutputdevice.cpp b/source/audio/midioutputdevice.cpp
index b4aed5a4..1c8d4273 100644
--- a/source/audio/midioutputdevice.cpp
+++ b/source/audio/midioutputdevice.cpp
@@ -14,7 +14,7 @@
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
-  
+
 #include "midioutputdevice.h"
 
 #include <RtMidi.h>
@@ -22,6 +22,7 @@
 #include <score/dynamic.h>
 #include <score/generalmidi.h>
 #include <cassert>
+#include <util/log.h>
 
 #ifdef __APPLE__
 #include "midisoftwaresynth.h"
@@ -38,7 +39,7 @@ MidiOutputDevice::MidiOutputDevice() : myMidiOut(nullptr)
     }
     catch (std::exception &e)
     {
-        std::cerr << e.what() << std::endl;
+        Log::e("could not start midisoftwaresynth: {}", e.what());
     };
 #endif
 
diff --git a/source/build/main.cpp b/source/build/main.cpp
index 882dc12f..a741a9e5 100644
--- a/source/build/main.cpp
+++ b/source/build/main.cpp
@@ -14,8 +14,9 @@
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
- 
+
 #include <app/appinfo.h>
+#include <app/log.h>
 #include <app/paths.h>
 #include <app/powertabeditor.h>
 #include <app/settings.h>
@@ -60,7 +61,7 @@ static void displayError(const std::string &reason)
     // If there is no QApplication instance, something went seriously wrong
     // during startup - just dump the error to the console.
     if (!QApplication::instance())
-        std::cerr << message << std::endl;
+        Log::e("{}", message);
     else
     {
         CrashDialog dialog(QString::fromStdString(message),
@@ -135,23 +136,25 @@ loadTranslations(QApplication &app, QTranslator &qt_translator,
                  QTranslator &ptb_translator)
 {
     QLocale locale;
-    qDebug() << "Finding translations for locale" << locale
-             << "with UI languages" << locale.uiLanguages();
+
+    Log::d("finding translations for locale:");
+    for (const auto& loc : locale.uiLanguages())
+        Log::d("  locale: {}", loc);
 
     for (auto &&path : Paths::getTranslationDirs())
     {
         QString dir = Paths::toQString(path);
-        qDebug() << "  - Checking" << dir;
+        Log::d("  - checking: {}", path.generic_string());
 
         if (ptb_translator.isEmpty() &&
             ptb_translator.load(locale, QStringLiteral("powertabeditor"),
                                 QStringLiteral("_"), dir))
         {
 #if (QT_VERSION >= QT_VERSION_CHECK(5,15,0))
-            qDebug() << "Loaded application translations from"
-                     << ptb_translator.filePath();
+            Log::d("loaded application translations from: {}",
+		   ptb_translator.filePath());
 #else
-            qDebug() << "Loaded application translations";
+            Log::d("loaded application translations");
 #endif
             app.installTranslator(&ptb_translator);
         }
@@ -161,10 +164,10 @@ loadTranslations(QApplication &app, QTranslator &qt_translator,
                                QStringLiteral("_"), dir))
         {
 #if (QT_VERSION >= QT_VERSION_CHECK(5,15,0))
-            qDebug() << "Loaded Qt base translations from"
-                     << qt_translator.filePath();
+            Log::d("loaded qt base translations from {}",
+                   qt_translator.filePath());
 #else
-            qDebug() << "Loaded Qt base translations";
+            Log::d("loaded Qt base translations");
 #endif
             app.installTranslator(&qt_translator);
         }
@@ -173,6 +176,10 @@ loadTranslations(QApplication &app, QTranslator &qt_translator,
 
 int main(int argc, char *argv[])
 {
+    Log::init(Log::Level::Debug, Paths::getLogPath());
+
+    Log::d("started powertab editor ({})", AppInfo::APPLICATION_VERSION);
+
     // Register handlers for unhandled exceptions and segmentation faults.
     std::set_terminate(terminateHandler);
     std::signal(SIGSEGV, signalHandler);
diff --git a/source/dialogs/infodialog.cpp b/source/dialogs/infodialog.cpp
index c3aec5fa..827f38a0 100644
--- a/source/dialogs/infodialog.cpp
+++ b/source/dialogs/infodialog.cpp
@@ -19,6 +19,9 @@
 #include "ui_infodialog.h"
 
 #include <app/appinfo.h>
+#include <app/paths.h>
+
+#include <util/log.h>
 
 #include <QClipboard>
 
@@ -47,9 +50,15 @@ void InfoDialog::setInfo()
         tr("You can grab development binaries here:\n"
            "  https://github.com/powertab/powertabeditor/actions");
 
-    const auto message = QString("%1\n\n%2").arg(
+    const auto message = QString(
+        "%1\n\n"
+        "%2\n\n"
+        "===============================\n"
+        "Logs:\n%3"
+    ).arg(
         qname,
-        developmentBinaryLocation
+        developmentBinaryLocation,
+        QString::fromStdString(Log::all())
     );
 
     ui->appInfo->setText(message);
diff --git a/source/formats/gp7/from_xml.cpp b/source/formats/gp7/from_xml.cpp
index 74800336..1de16272 100644
--- a/source/formats/gp7/from_xml.cpp
+++ b/source/formats/gp7/from_xml.cpp
@@ -19,6 +19,7 @@
 
 #include <formats/fileformat.h>
 #include <score/generalmidi.h>
+#include <util/log.h>
 
 #include <boost/algorithm/string/split.hpp>
 #include <string>
@@ -167,8 +168,7 @@ parseChordNote(const pugi::xml_node &node)
         note.myAccidental = *accidental;
     else
     {
-        std::cerr << "Unknown accidental type: " << accidental_text
-                  << std::endl;
+        Log::e("unknown accidental type: {}", accidental_text);
     }
 
     return note;
@@ -189,7 +189,7 @@ parseChordDegree(const pugi::xml_node &chord_node, const char *name)
     if (auto alteration = Util::toEnum<Alteration>(text))
         degree.myAlteration = *alteration;
     else
-        std::cerr << "Unknown alteration type: " << text << std::endl;
+        Log::e("unknown alteration type: {}", text);
 
     return degree;
 }
@@ -425,8 +425,7 @@ parseMasterBars(const pugi::xml_node &master_bars_node)
                     master_bar.myDirectionTargets.push_back(*target);
                 else
                 {
-                    std::cerr << "Invalid direction target type: " << target_str
-                              << std::endl;
+                    Log::e("invalid direction target type: {}", target_str);
                 }
             }
 
@@ -438,8 +437,7 @@ parseMasterBars(const pugi::xml_node &master_bars_node)
                     master_bar.myDirectionJumps.push_back(*jump);
                 else
                 {
-                    std::cerr << "Invalid direction jump type: " << jump_str
-                              << std::endl;
+                    Log::e("invalid direction jump type: {}", jump_str);
                 }
             }
         }
@@ -463,7 +461,7 @@ parseBars(const pugi::xml_node &bars_node)
         if (auto clef_type = Util::toEnum<Gp7::Bar::ClefType>(clef_name))
             bar.myClefType = *clef_type;
         else
-            std::cerr << "Invalid clef type: " << clef_name << std::endl;
+            Log::e("invalid clef type: {}", clef_name);
 
         // TODO - import the 'Ottavia' key if the clef has 8va, etc
 
@@ -507,7 +505,7 @@ parseBeats(const pugi::xml_node &beats_node, Gp7::Version version)
         {
             beat.myOttavia = Util::toEnum<Gp7::Beat::Ottavia>(ottavia);
             if (!beat.myOttavia)
-                std::cerr << "Invalid ottavia value: " << ottavia << std::endl;
+                Log::e("invalid ottavia value: {}", ottavia);
         }
 
         beat.myFreeText = node.child_value("FreeText");
@@ -654,8 +652,7 @@ parseNotes(const pugi::xml_node &notes_node)
                 note.myHarmonic = Util::toEnum<HarmonicType>(harmonic_type);
                 if (!note.myHarmonic)
                 {
-                    std::cerr << "Unknown harmonic type: " << harmonic_type
-                              << std::endl;
+                    Log::e("unknown harmonic type: {}", harmonic_type);
                 }
             }
             else if (name == "Bended")
@@ -718,8 +715,7 @@ parseNotes(const pugi::xml_node &notes_node)
             note.myLeftFinger = Util::toEnum<FingerType>(finger_type);
             if (!note.myLeftFinger)
             {
-                std::cerr << "Unknown finger type: " << finger_type
-                          << std::endl;
+                Log::e("unknown finger type: {}", finger_type);
             }
         }
 
diff --git a/source/formats/gp7/to_pt2.cpp b/source/formats/gp7/to_pt2.cpp
index 6f8635e0..3bc38941 100644
--- a/source/formats/gp7/to_pt2.cpp
+++ b/source/formats/gp7/to_pt2.cpp
@@ -38,6 +38,7 @@
 #include <score/utils/scorepolisher.h>
 #include <score/voiceutils.h>
 #include <util/tostring.h>
+#include <util/log.h>
 
 #include <iostream>
 #include <unordered_set>
@@ -182,7 +183,7 @@ getHarmonicPitchOffset(double harmonic_fret)
     }
     else
     {
-        std::cerr << "Unexpected harmonic type" << std::endl;
+        Log::e("unexpected harmonic type");
         return 12;
     }
 }
diff --git a/source/formats/powertab_old/powertabdocument/macros.cpp b/source/formats/powertab_old/powertabdocument/macros.cpp
index a3ba272b..a3178c51 100644
--- a/source/formats/powertab_old/powertabdocument/macros.cpp
+++ b/source/formats/powertab_old/powertabdocument/macros.cpp
@@ -14,14 +14,19 @@
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
-  
+
 #include "macros.h"
+
+#include <util/log.h>
+
 #include <algorithm> // std::transform
 #include <iostream>
 
 void logToDebug(const std::string& msg, const std::string& file, int line)
 {
-    std::cerr << msg << std::endl << file << std::endl << "Line: " <<  line << std::endl;
+    Log::e("{}", msg);
+    Log::e("{}", file);
+    Log::e("line: {}", line);
 }
 
 std::string ArabicToRoman(uint32_t number, bool upperCase)
diff --git a/source/score/serialization.cpp b/source/score/serialization.cpp
index ff426ad1..c1980503 100644
--- a/source/score/serialization.cpp
+++ b/source/score/serialization.cpp
@@ -42,8 +42,7 @@ InputArchive::InputArchive(std::istream &is)
     }
     else
     {
-        std::cerr << "Warning: Reading an unknown file version - " << version
-                  << std::endl;
+        Log::e("warning: reading an unknown file version - {}", version);
 
         // Reading in a newer version. Just do the best we can with the latest
         // file version we're aware of.
diff --git a/source/score/serialization.h b/source/score/serialization.h
index d36051b1..e060ca47 100644
--- a/source/score/serialization.h
+++ b/source/score/serialization.h
@@ -31,6 +31,7 @@
 #include <util/date.h>
 #include <util/enumflags.h>
 #include <util/enumtostring_fwd.h>
+#include <util/log.h>
 #include <vector>
 
 namespace ScoreUtils
@@ -113,8 +114,7 @@ namespace detail
                         val = *result;
                     else
                     {
-                        std::cerr << "Unknown enum value: " << text
-                                  << std::endl;
+                        Log::e("unknown enum value: {}", text);
                     }
                 }
             }
diff --git a/source/score/utils/directionindex.cpp b/source/score/utils/directionindex.cpp
index 3d663221..51445669 100644
--- a/source/score/utils/directionindex.cpp
+++ b/source/score/utils/directionindex.cpp
@@ -19,6 +19,7 @@
 
 #include <iostream>
 #include <score/score.h>
+#include <util/log.h>
 
 DirectionIndex::DirectionIndex(const Score &score)
     : myScore(score), myActiveSymbol(DirectionSymbol::ActiveNone)
@@ -147,8 +148,7 @@ SystemLocation DirectionIndex::followDirection(DirectionSymbol::SymbolType type)
     else
     {
         // This should not happen if the score is properly written.
-        std::cerr << "Could not find the symbol "
-                  << static_cast<int>(nextSymbol) << std::endl;
+        Log::e("Could not find the symbol {}", static_cast<int>(nextSymbol));
         return SystemLocation(0, 0);
     }
 }
diff --git a/source/util/CMakeLists.txt b/source/util/CMakeLists.txt
index 436aa137..b2037adf 100644
--- a/source/util/CMakeLists.txt
+++ b/source/util/CMakeLists.txt
@@ -32,6 +32,7 @@ if ( PLATFORM_OSX )
 endif ()
 
 set( srcs
+    log.cpp
     settingstree.cpp
     version.cpp
 
@@ -43,6 +44,7 @@ set( headers
     enumflags.h
     enumtostring.h
     enumtostring_fwd.h
+    log.h
     settingstree.h
     tostring.h
     toutf8.h
@@ -62,5 +64,5 @@ pte_library(
     HEADERS ${headers}
     DEPENDS
         PUBLIC Boost::headers
-        PRIVATE nlohmann_json::nlohmann_json ${platform_depends}
+        PRIVATE fmt::fmt nlohmann_json::nlohmann_json ${platform_depends}
 )
diff --git a/source/util/log.cpp b/source/util/log.cpp
new file mode 100644
index 00000000..51147b1b
--- /dev/null
+++ b/source/util/log.cpp
@@ -0,0 +1,138 @@
+/* Copyright (C) 2021-2024 Simon Symeonidis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "log.h"
+
+#include <chrono>
+#include <iostream>
+#include <iomanip> /* put_time */
+#include <fstream>
+#include <sstream>
+#include <mutex>
+#include <optional>
+#include <vector>
+
+namespace Log {
+
+enum Level FilterLevel = Level::Debug;
+
+std::optional<std::ofstream> logFile;
+
+std::filesystem::path logPath;
+
+std::mutex lock;
+
+void trim(const unsigned int count)
+{
+    /* a poorman's circular buffer that keeps the last 'count' log lines. */
+    std::vector<std::string> v(count);
+
+    std::ifstream input(logPath);
+    std::size_t index = 0;
+    std::string s;
+    while (std::getline(input, s)) {
+        v[index % count] = s;
+	index++;
+    }
+
+    input.close();
+
+    // required because of len/cap discrepancy in vector used as a circular
+    // buffer.
+    const auto upto = (count == index ? index : count);
+
+    std::ofstream output(logPath, std::ios::trunc);
+    if (output.good()) {
+        for (size_t i = 0; i < upto; ++i)
+            output << v[(index + i) % count] << std::endl;
+    } else {
+        std::cerr << "could not open log file for trimming" << std::endl;
+    }
+    output.close();
+}
+
+void init(enum Level lvl, std::filesystem::path lp)
+{
+    FilterLevel = lvl;
+    logPath = lp;
+
+    // keep only the last X lines
+    trim(1000);
+
+    if (!logFile) {
+        const auto mode = std::ios_base::out | std::ios_base::app;
+        logFile = std::ofstream(logPath, mode);
+    }
+}
+
+void emitLog(enum Level level, const std::string& str)
+{
+    std::lock_guard<std::mutex> _guard(Log::lock);
+
+    /* formats a timestamp in a rfc3339 fashion; I believe the system clock
+     * defaults to epoch, which should be UTC, but I might be wrong.  */
+    const auto timestamp_now_str_fn = []() -> std::string {
+	auto now = std::chrono::system_clock::now();
+	auto now_t = std::chrono::system_clock::to_time_t(now);
+
+	std::stringstream ss;
+	ss << std::put_time(std::localtime(&now_t), "%Y-%m-%dT%H:%M:%SZ");
+	return ss.str();
+    };
+
+    const auto level_str_fn = [](enum Level l) noexcept {
+        switch (l) {
+        case Level::Debug: return "[debug]";
+        case Level::Info: return "[info]";
+        case Level::Notify: return "[notify]";
+        case Level::Warning: return "[warn]";
+        case Level::Error: return "[error]";
+        /* unreachable */
+	default:
+	    return "unknown";
+        }
+    };
+
+    std::cout
+        << timestamp_now_str_fn() << ": "
+        << level_str_fn(level) << ": "
+        << str
+        << std::endl;
+
+    if (logFile.value().good()) {
+        logFile.value()
+            << timestamp_now_str_fn() << ": "
+            << level_str_fn(level) << ": "
+            << str
+            << std::endl;
+    } else {
+        std::cout << fmt::format(
+            "{} {} could not open file at ({})",
+            timestamp_now_str_fn(),
+	    level_str_fn(Level::Warning),
+	    logPath.generic_string()
+	);
+    }
+}
+
+std::string all()
+{
+    std::stringstream ss;
+    std::ifstream ifs(logPath);
+    ss << ifs.rdbuf();
+    return ss.str();
+}
+
+}
diff --git a/source/util/log.h b/source/util/log.h
new file mode 100644
index 00000000..78543410
--- /dev/null
+++ b/source/util/log.h
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2021-2024 Simon Symeonidis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef UTIL_LOG_H
+#define UTIL_LOG_H
+
+#include <filesystem>
+#include <string>
+
+/* TODO: fmtlib: replace with std, when all compilers support `format'. */
+#include <fmt/core.h>
+
+namespace Log {
+
+enum class Level {
+    Debug = 0,
+    Info = 1,
+    Notify = 2,
+    Warning = 3,
+    Error = 4,
+};
+
+/**
+ * toggleable log level - set this to the minimum level to filter from a la
+ * rfc5424.
+ */
+extern enum Level CurrentLevel;
+
+void init(enum Level lvl, std::filesystem::path logPath);
+
+/**
+ * return the full contents of the log file
+ */
+std::string all();
+
+/**
+ * takes a string, and emits it.  Our emitters consider only a log file on the
+ * platform, and print to console if there is a problem if the file can not be
+ * opened.  The emitters will also add the current timestamp, and the log level
+ * of the message.
+ */
+void emitLog(enum Level level, const std::string& str);
+
+template <typename... Args>
+void backend(const enum Level level, std::string_view fmt, Args&&... args)
+{
+    emitLog(level, fmt::vformat(fmt, fmt::make_format_args(args...)));
+}
+
+template <typename... Args>
+void d(std::string_view fmt, Args&&... args) { backend(Level::Debug, fmt, std::forward<Args>(args)...); }
+
+template <typename... Args>
+void i(std::string_view fmt, Args&&... args) { backend(Level::Info, fmt, std::forward<Args>(args)...); }
+
+template <typename... Args>
+void n(std::string_view fmt, Args&&... args) { backend(Level::Notify, fmt, std::forward<Args>(args)...); }
+
+template <typename... Args>
+void w(std::string_view fmt, Args&&... args) { backend(Level::Warning, fmt, std::forward<Args>(args)...); }
+
+template <typename... Args>
+void e(std::string_view fmt, Args&&... args) { backend(Level::Error, fmt, std::forward<Args>(args)...); }
+
+}
+#endif
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 5ff47c82..3524e10c 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -188,6 +188,7 @@ pte_executable(
     PCH_EXCLUDE test_main.cpp
     DEPENDS
         doctest::doctest
+        fmt::fmt
         pteapp
         rtmidi::rtmidi
 )