diff --git a/avogadro/qtplugins/forcefield/scriptenergy.cpp b/avogadro/qtplugins/forcefield/scriptenergy.cpp
index 293d1cac02..abd4a60222 100644
--- a/avogadro/qtplugins/forcefield/scriptenergy.cpp
+++ b/avogadro/qtplugins/forcefield/scriptenergy.cpp
@@ -27,6 +27,10 @@
 #include <qjsonobject.h>
 #include <qjsonvalue.h>
 
+// nlohmann json for msgpack
+#include <nlohmann/json.hpp>
+using json = nlohmann::json;
+
 namespace Avogadro::QtPlugins {
 
 ScriptEnergy::ScriptEnergy(const QString& scriptFileName_)
@@ -57,6 +61,11 @@ void ScriptEnergy::setMolecule(Core::Molecule* mol)
 {
   m_molecule = mol;
 
+  qDebug() << " ScriptEnergy::setMolecule() " << mol->formula().c_str()
+           << " method: " << m_identifier.c_str()
+           << " script: " << m_interpreter->scriptFilePath() << " msgPack "
+           << m_msgPack;
+
   // should check if the molecule is valid for this script
   // .. this should never happen, but let's be defensive
   if (mol == nullptr || m_interpreter == nullptr) {
@@ -116,23 +125,41 @@ Real ScriptEnergy::value(const Eigen::VectorXd& x)
 
   // write the new coordinates and read the energy
   QByteArray input;
-  for (Index i = 0; i < x.size(); i += 3) {
-    // write as x y z (space separated)
-    input += QString::number(x[i]).toUtf8() + " " +
-             QString::number(x[i + 1]).toUtf8() + " " +
-             QString::number(x[i + 2]).toUtf8() + "\n";
+  if (m_msgPack) {
+    json j;
+    j["coordinates"] = json::array();
+    for (Index i = 0; i < x.size(); ++i) {
+      j["coordinates"].push_back(x[i]);
+    }
+    auto msgPack = json::to_msgpack(j);
+    input = QByteArray::fromRawData(
+      reinterpret_cast<const char*>(msgPack.data()), msgPack.size());
+  } else {
+    for (Index i = 0; i < x.size(); i += 3) {
+      // write as x y z (space separated)
+      input += QString::number(x[i]).toUtf8() + " " +
+               QString::number(x[i + 1]).toUtf8() + " " +
+               QString::number(x[i + 2]).toUtf8() + "\n";
+    }
   }
   QByteArray result = m_interpreter->asyncWriteAndResponse(input);
 
-  // go through lines in result until we see "AvogadroEnergy: "
-  QStringList lines = QString(result).remove('\r').split('\n');
   double energy = 0.0;
-  for (auto line : lines) {
-    if (line.startsWith("AvogadroEnergy:")) {
-      QStringList items = line.split(" ", Qt::SkipEmptyParts);
-      if (items.size() > 1) {
-        energy = items[1].toDouble();
-        break;
+  if (m_msgPack) {
+    json j = json::from_msgpack(result.toStdString());
+    if (j.find("energy") != j.end()) {
+      return j["energy"];
+    }
+  } else {
+    // go through lines in result until we see "AvogadroEnergy: "
+    QStringList lines = QString(result).remove('\r').split('\n');
+    for (auto line : lines) {
+      if (line.startsWith("AvogadroEnergy:")) {
+        QStringList items = line.split(" ", Qt::SkipEmptyParts);
+        if (items.size() > 1) {
+          energy = items[1].toDouble();
+          break;
+        }
       }
     }
   }
@@ -150,36 +177,56 @@ void ScriptEnergy::gradient(const Eigen::VectorXd& x, Eigen::VectorXd& grad)
   // Get the gradient from the script
   // write the new coordinates and read the energy
   QByteArray input;
-  for (Index i = 0; i < x.size(); i += 3) {
-    // write as x y z (space separated)
-    input += QString::number(x[i]).toUtf8() + " " +
-             QString::number(x[i + 1]).toUtf8() + " " +
-             QString::number(x[i + 2]).toUtf8() + "\n";
+  if (m_msgPack) {
+    json j;
+    j["coordinates"] = json::array();
+    for (Index i = 0; i < x.size(); ++i) {
+      j["coordinates"].push_back(x[i]);
+    }
+    auto msgPack = json::to_msgpack(j);
+    input = QByteArray::fromRawData(
+      reinterpret_cast<const char*>(msgPack.data()), msgPack.size());
+  } else {
+    for (Index i = 0; i < x.size(); i += 3) {
+      // write as x y z (space separated)
+      input += QString::number(x[i]).toUtf8() + " " +
+               QString::number(x[i + 1]).toUtf8() + " " +
+               QString::number(x[i + 2]).toUtf8() + "\n";
+    }
   }
   QByteArray result = m_interpreter->asyncWriteAndResponse(input);
 
-  // parse the result
-  // first split on newlines
-  QStringList lines = QString(result).remove('\r').split('\n');
-  unsigned int i = 0;
-  bool readingGrad = false;
-  for (auto line : lines) {
-    if (line.startsWith("AvogadroGradient:")) {
-      readingGrad = true;
-      continue; // next line
+  if (m_msgPack) {
+    json j = json::from_msgpack(result.toStdString());
+    if (j.find("gradient") != j.end()) {
+      for (Index i = 0; i < x.size(); ++i) {
+        grad[i] = j["gradient"][i];
+      }
     }
-
-    if (readingGrad) {
-      QStringList items = line.split(" ", Qt::SkipEmptyParts);
-      if (items.size() == 3) {
-        grad[i] = items[0].toDouble();
-        grad[i + 1] = items[1].toDouble();
-        grad[i + 2] = items[2].toDouble();
-        i += 3;
+  } else {
+    // parse the result
+    // first split on newlines
+    QStringList lines = QString(result).remove('\r').split('\n');
+    unsigned int i = 0;
+    bool readingGrad = false;
+    for (auto line : lines) {
+      if (line.startsWith("AvogadroGradient:")) {
+        readingGrad = true;
+        continue; // next line
       }
 
-      if (i > x.size())
-        break;
+      if (readingGrad) {
+        QStringList items = line.split(" ", Qt::SkipEmptyParts);
+        if (items.size() == 3) {
+          grad[i] = items[0].toDouble();
+          grad[i + 1] = items[1].toDouble();
+          grad[i + 2] = items[2].toDouble();
+          i += 3;
+        }
+
+        if (i > x.size())
+          break;
+      }
     }
   }
 
@@ -229,6 +276,7 @@ void ScriptEnergy::resetMetaData()
   m_valid = false;
   m_gradients = false;
   m_ions = false;
+  m_msgPack = false;
   m_radicals = false;
   m_unitCells = false;
   m_inputFormat = NotUsed;
@@ -351,6 +399,14 @@ void ScriptEnergy::readMetaData()
   }
   m_radicals = metaData["radical"].toBool();
 
+  // msgpack is optional
+  // defaults to not used
+  if (metaData["msgpack"].isBool()) {
+    m_msgPack = metaData["msgpack"].toBool();
+  } else if (metaData["msgPack"].isBool()) {
+    m_msgPack = metaData["msgPack"].toBool();
+  }
+
   // get the element mask
   // (if it doesn't exist, the default is no elements anyway)
   m_valid = parseElements(metaData);
diff --git a/avogadro/qtplugins/forcefield/scriptenergy.h b/avogadro/qtplugins/forcefield/scriptenergy.h
index 9aab7bf0a1..6e4125d7a6 100644
--- a/avogadro/qtplugins/forcefield/scriptenergy.h
+++ b/avogadro/qtplugins/forcefield/scriptenergy.h
@@ -94,6 +94,7 @@ class ScriptEnergy : public Avogadro::Calc::EnergyCalculator
   bool m_ions;
   bool m_radicals;
   bool m_unitCells;
+  bool m_msgPack = false;
 
   std::string m_identifier;
   std::string m_name;
diff --git a/avogadro/qtplugins/forcefield/scripts/ani2x.py b/avogadro/qtplugins/forcefield/scripts/ani2x.py
index 06266cf08b..998a7e8f1b 100644
--- a/avogadro/qtplugins/forcefield/scripts/ani2x.py
+++ b/avogadro/qtplugins/forcefield/scripts/ani2x.py
@@ -5,6 +5,12 @@
 import json
 import sys
 
+try:
+    import msgpack
+    msgpack_available = True
+except ImportError:
+    msgpack_available = False
+
 try:
     import torch
     import torchani
@@ -34,6 +40,8 @@ def getMetaData():
         "ion": False,
         "radical": False,
     }
+    if (msgpack_available):
+        metaData["msgpack"] = True
     return metaData
 
 
@@ -54,19 +62,35 @@ def run(filename):
     num_atoms = len(atoms)
     while True:
         # read new coordinates from stdin
-        for i in range(num_atoms):
-            np_coords[i] = np.fromstring(input(), sep=" ")
+        if (msgpack_available):
+            # unpack the coordinates
+            data = msgpack.unpackb(sys.stdin.buffer.read())
+            np_coords = np.array(data["coordinates"], dtype=float).reshape(-1, 3)
+        else:
+            for i in range(num_atoms):
+                np_coords[i] = np.fromstring(input(), sep=" ")
         coordinates = torch.tensor([np_coords], requires_grad=True, device=device)
 
         # first print the energy of these coordinates
         energy = model((species, coordinates)).energies
-        print("AvogadroEnergy:", energy)  # in Hartree
+        if (msgpack_available):
+            response = { "energy": energy }
+        else:
+            print("AvogadroEnergy:", energy)  # in Hartree
 
         # now print the gradient on each atom
-        print("AvogadroGradient:")
         derivative = torch.autograd.grad(energy.sum(), coordinates)[0]
-        for i in range(num_atoms):
-            print(derivative[0][i][0].item(), derivative[0][i][1].item(), derivative[0][i][2].item())
+
+        if (msgpack_available):
+            gradient = []
+            for i in range(num_atoms):
+                gradient.append([derivative[0][i][0].item(), derivative[0][i][1].item(), derivative[0][i][2].item()])
+            response["gradient"] = gradient
+            print(msgpack.packb(response))
+        else:
+            print("AvogadroGradient:")
+            for i in range(num_atoms):
+                print(derivative[0][i][0].item(), derivative[0][i][1].item(), derivative[0][i][2].item())
 
 
 if __name__ == "__main__":
diff --git a/avogadro/qtplugins/forcefield/scripts/gaff.py b/avogadro/qtplugins/forcefield/scripts/gaff.py
index 491c66d1f6..9c3c4ca745 100644
--- a/avogadro/qtplugins/forcefield/scripts/gaff.py
+++ b/avogadro/qtplugins/forcefield/scripts/gaff.py
@@ -5,6 +5,12 @@
 import json
 import sys
 
+try:
+    import msgpack
+    msgpack_available = True
+except ImportError:
+    msgpack_available = False
+
 try:
     from openbabel import pybel
     import numpy as np
@@ -30,6 +36,8 @@ def getMetaData():
         "ion": False,
         "radical": False,
     }
+    if (msgpack_available):
+        metaData["msgpack"] = True
     return metaData
 
 
@@ -48,24 +56,42 @@ def run(filename):
     num_atoms = len(mol.atoms)
     while True:
         # read new coordinates from stdin
-        for i in range(num_atoms):
-            coordinates = np.fromstring(input(), sep=" ")
-            atom = mol.atoms[i]
-            atom.OBAtom.SetVector(coordinates[0], coordinates[1], coordinates[2])
+        if (msgpack_available):
+            # unpack the coordinates
+            data = msgpack.unpackb(sys.stdin.buffer.read())
+            np_coords = np.array(data["coordinates"], dtype=float).reshape(-1, 3)
+            for i in range(num_atoms):
+                atom = mol.atoms[i]
+                atom.OBAtom.SetVector(np_coords[i][0], np_coords[i][1], np_coords[i][2])
+        else:
+            for i in range(num_atoms):
+                coordinates = np.fromstring(input(), sep=" ")
+                atom = mol.atoms[i]
+                atom.OBAtom.SetVector(coordinates[0], coordinates[1], coordinates[2])
 
         # update the molecule geometry for the next energy
         ff.SetCoordinates(mol.OBMol)
 
         # first print the energy of these coordinates
         energy = ff.Energy(True)  # in kJ/mol
-        print("AvogadroEnergy:", energy)  # in kJ/mol
+        if (msgpack_available):
+            response = {"energy": energy}
+        else:
+            print("AvogadroEnergy:", energy)  # in kJ/mol
 
         # now print the gradient on each atom
-        print("AvogadroGradient:")
-        for atom in mol.atoms:
-            grad = ff.GetGradient(atom.OBAtom)
-            print(-1.0*grad.GetX(), -1.0*grad.GetY(), -1.0*grad.GetZ())
-
+        if (msgpack_available):
+            gradient = []
+            for atom in mol.atoms:
+                grad = ff.GetGradient(atom.OBAtom)
+                gradient.append([-1.0*grad.GetX(), -1.0*grad.GetY(), -1.0*grad.GetZ()])
+            response["gradient"] = gradient
+            print(msgpack.packb(response))
+        else:
+            print("AvogadroGradient:")
+            for atom in mol.atoms:
+                grad = ff.GetGradient(atom.OBAtom)
+                print(-1.0*grad.GetX(), -1.0*grad.GetY(), -1.0*grad.GetZ())
 
 
 if __name__ == "__main__":
diff --git a/avogadro/qtplugins/forcefield/scripts/gfn1.py b/avogadro/qtplugins/forcefield/scripts/gfn1.py
index fdb5a5fb1f..8b6b1211eb 100644
--- a/avogadro/qtplugins/forcefield/scripts/gfn1.py
+++ b/avogadro/qtplugins/forcefield/scripts/gfn1.py
@@ -5,6 +5,12 @@
 import json
 import sys
 
+try:
+    import msgpack
+    msgpack_available = True
+except ImportError:
+    msgpack_available = False
+
 try:
     import numpy as np
     from xtb.libxtb import VERBOSITY_MUTED
@@ -29,6 +35,8 @@ def getMetaData():
         "ion": True,
         "radical": True,
     }
+    if (msgpack_available):
+        metaData["msgpack"] = True
     return metaData
 
 
@@ -63,25 +71,41 @@ def run(filename):
     # we loop forever - Avogadro will kill the process when done
     while(True):
         # read new coordinates from stdin
-        for i in range(len(atoms)):
-            coordinates[i] = np.fromstring(input())
-        # .. convert from Angstrom to Bohr
-        coordinates /= 0.52917721067
+        if (msgpack_available):
+            # unpack the coordinates
+            data = msgpack.unpackb(sys.stdin.buffer.read())
+            np_coords = np.array(data["coordinates"], dtype=float).reshape(-1, 3)
+            # .. we need to convert from Angstrom to Bohr
+            np_coords /= 0.52917721067
+            coordinates = np_coords
+        else:
+            for i in range(len(atoms)):
+                coordinates[i] = np.fromstring(input(), sep=' ')
+            # .. convert from Angstrom to Bohr
+            coordinates /= 0.52917721067
 
         # update the calculator and run a new calculation
         calc.update(coordinates)
         calc.singlepoint(res)
 
         # first print the energy of these coordinates
-        print("AvogadroEnergy:", res.get_energy())  # in Hartree
+        if (msgpack_available):
+            response = {"energy": res.get_energy()}
+        else:
+            print("AvogadroEnergy:", res.get_energy())  # in Hartree
 
         # now print the gradient
         # .. we don't want the "[]" in the output
-        print("AvogadroGradient:")
-        grad = res.get_gradient() * 4961.475  # convert units
-        output = np.array2string(grad)
-        output = output.replace("[", "").replace("]", "")
-        print(output)
+        if (msgpack_available):
+            grad = res.get_gradient() * 4961.475
+            response["gradient"] = grad.tolist()
+            print(msgpack.packb(response))
+        else:
+            print("AvogadroGradient:")
+            grad = res.get_gradient() * 4961.475  # convert units
+            output = np.array2string(grad)
+            output = output.replace("[", "").replace("]", "")
+            print(output)
 
 
 if __name__ == "__main__":
diff --git a/avogadro/qtplugins/forcefield/scripts/gfn2.py b/avogadro/qtplugins/forcefield/scripts/gfn2.py
index 7b67c67c7e..e21624d244 100644
--- a/avogadro/qtplugins/forcefield/scripts/gfn2.py
+++ b/avogadro/qtplugins/forcefield/scripts/gfn2.py
@@ -5,6 +5,12 @@
 import json
 import sys
 
+try:
+    import msgpack
+    msgpack_available = True
+except ImportError:
+    msgpack_available = False
+
 try:
     import numpy as np
     from xtb.libxtb import VERBOSITY_MUTED
@@ -29,6 +35,8 @@ def getMetaData():
         "ion": True,
         "radical": True,
     }
+    if (msgpack_available):
+        metaData["msgpack"] = True
     return metaData
 
 
@@ -63,25 +71,40 @@ def run(filename):
     # we loop forever - Avogadro will kill the process when done
     while(True):
         # read new coordinates from stdin
-        for i in range(len(atoms)):
-            coordinates[i] = np.fromstring(input())
-        # .. convert from Angstrom to Bohr
-        coordinates /= 0.52917721067
+        if (msgpack_available):
+            # unpack the coordinates
+            data = msgpack.unpackb(sys.stdin.buffer.read())
+            np_coords = np.array(data["coordinates"], dtype=float).reshape(-1, 3)
+            # .. we need to convert from Angstrom to Bohr
+            np_coords /= 0.52917721067
+            coordinates = np_coords
+        else:
+            for i in range(len(atoms)):
+                coordinates[i] = np.fromstring(input(), sep=' ')
+            # .. convert from Angstrom to Bohr
+            coordinates /= 0.52917721067
 
         # update the calculator and run a new calculation
         calc.update(coordinates)
         calc.singlepoint(res)
 
         # first print the energy of these coordinates
-        print("AvogadroEnergy:", res.get_energy())  # in Hartree
+        if (msgpack_available):
+            response = {"energy": res.get_energy()}
+        else:
+            print("AvogadroEnergy:", res.get_energy())  # in Hartree
 
         # now print the gradient
-        # .. we don't want the "[]" in the output
-        print("AvogadroGradient:")
-        grad = res.get_gradient() * 4961.475  # convert units
-        output = np.array2string(grad)
-        output = output.replace("[", "").replace("]", "")
-        print(output)
+        if (msgpack_available):
+            grad = res.get_gradient() * 4961.475
+            response["gradient"] = grad.tolist()
+            print(msgpack.packb(response))
+        else:
+            print("AvogadroGradient:")
+            grad = res.get_gradient() * 4961.475  # convert units
+            output = np.array2string(grad)
+            output = output.replace("[", "").replace("]", "")
+            print(output)
 
 
 if __name__ == "__main__":
diff --git a/avogadro/qtplugins/forcefield/scripts/gfnff.py b/avogadro/qtplugins/forcefield/scripts/gfnff.py
index ddb0d44596..2e39614a5a 100644
--- a/avogadro/qtplugins/forcefield/scripts/gfnff.py
+++ b/avogadro/qtplugins/forcefield/scripts/gfnff.py
@@ -6,6 +6,12 @@
 import sys
 import os
 
+try:
+    import msgpack
+    msgpack_available = True
+except ImportError:
+    msgpack_available = False
+
 try:
     import numpy as np
     from xtb.libxtb import VERBOSITY_MUTED
@@ -74,6 +80,8 @@ def getMetaData():
         "ion": True,
         "radical": False,
     }
+    if (msgpack_available):
+        metaData["msgpack"] = True
     return metaData
 
 
@@ -105,7 +113,7 @@ def run(filename):
     #  and then just ignore it
     f = io.BytesIO()
     with stdout_redirector(f):
-        calc = Calculator(Param.GFNFF, atoms, coordinates, 
+        calc = Calculator(Param.GFNFF, atoms, coordinates,
                         charge=charge, uhf=spin)
         calc.set_verbosity(VERBOSITY_MUTED)
         res = calc.singlepoint()
@@ -113,25 +121,41 @@ def run(filename):
     # we loop forever - Avogadro will kill our process when done
     while True:
         # read new coordinates from stdin
-        for i in range(len(atoms)):
-            coordinates[i] = np.fromstring(input(), sep=' ')
-        # .. convert from Angstrom to Bohr
-        coordinates /= 0.52917721067
+        if (msgpack_available):
+            # unpack the coordinates
+            data = msgpack.unpackb(sys.stdin.buffer.read())
+            np_coords = np.array(data["coordinates"], dtype=float).reshape(-1, 3)
+            # .. we need to convert from Angstrom to Bohr
+            np_coords /= 0.52917721067
+            coordinates = np_coords
+        else:
+            for i in range(len(atoms)):
+                coordinates[i] = np.fromstring(input(), sep=' ')
+            # .. convert from Angstrom to Bohr
+            coordinates /= 0.52917721067
 
         # update the calculator and run a new calculation
         calc.update(coordinates)
         calc.singlepoint(res)
 
-        print("AvogadroEnergy:", res.get_energy())  # in Hartree
+        if (msgpack_available):
+            response = {"energy": res.get_energy()}
+        else:
+            print("AvogadroEnergy:", res.get_energy())  # in Hartree
         # times 2625.5 kJ/mol
 
         # now print the gradient
         # .. we don't want the "[]" in the output
-        print("AvogadroGradient:")
-        grad = res.get_gradient() * 4961.475  # convert units
-        output = np.array2string(grad)
-        output = output.replace("[", "").replace("]", "")
-        print(output)
+        if (msgpack_available):
+            grad = res.get_gradient() * 4961.475
+            response["gradient"] = grad.tolist()
+            print(msgpack.packb(response))
+        else:
+            print("AvogadroGradient:")
+            grad = res.get_gradient() * 4961.475  # convert units
+            output = np.array2string(grad)
+            output = output.replace("[", "").replace("]", "")
+            print(output)
 
 
 if __name__ == "__main__":
diff --git a/avogadro/qtplugins/forcefield/scripts/mmff94.py b/avogadro/qtplugins/forcefield/scripts/mmff94.py
index 3206123c40..4167dc0fd2 100644
--- a/avogadro/qtplugins/forcefield/scripts/mmff94.py
+++ b/avogadro/qtplugins/forcefield/scripts/mmff94.py
@@ -5,6 +5,12 @@
 import json
 import sys
 
+try:
+    import msgpack
+    msgpack_available = True
+except ImportError:
+    msgpack_available = False
+
 try:
     from openbabel import pybel
     import numpy as np
@@ -30,6 +36,8 @@ def getMetaData():
         "ion": False,
         "radical": False,
     }
+    if (msgpack_available):
+        metaData["msgpack"] = True
     return metaData
 
 
@@ -48,23 +56,42 @@ def run(filename):
     num_atoms = len(mol.atoms)
     while True:
         # read new coordinates from stdin
-        for i in range(num_atoms):
-            coordinates = np.fromstring(input(), sep=" ")
-            atom = mol.atoms[i]
-            atom.OBAtom.SetVector(coordinates[0], coordinates[1], coordinates[2])
+        if (msgpack_available):
+            # unpack the coordinates
+            data = msgpack.unpackb(sys.stdin.buffer.read())
+            np_coords = np.array(data["coordinates"], dtype=float).reshape(-1, 3)
+            for i in range(num_atoms):
+                atom = mol.atoms[i]
+                atom.OBAtom.SetVector(np_coords[i][0], np_coords[i][1], np_coords[i][2])
+        else:
+            for i in range(num_atoms):
+                coordinates = np.fromstring(input(), sep=" ")
+                atom = mol.atoms[i]
+                atom.OBAtom.SetVector(coordinates[0], coordinates[1], coordinates[2])
 
         # update the molecule geometry for the next energy
         ff.SetCoordinates(mol.OBMol)
 
         # first print the energy of these coordinates
         energy = ff.Energy(True)  # in kJ/mol
-        print("AvogadroEnergy:", energy)  # in kJ/mol
+        if (msgpack_available):
+            response = {"energy": energy}
+        else:
+            print("AvogadroEnergy:", energy)  # in kJ/mol
 
         # now print the gradient on each atom
-        print("AvogadroGradient:")
-        for atom in mol.atoms:
-            grad = ff.GetGradient(atom.OBAtom)
-            print(-1.0*grad.GetX(), -1.0*grad.GetY(), -1.0*grad.GetZ())
+        if (msgpack_available):
+            gradient = []
+            for atom in mol.atoms:
+                grad = ff.GetGradient(atom.OBAtom)
+                gradient.append([-1.0*grad.GetX(), -1.0*grad.GetY(), -1.0*grad.GetZ()])
+            response["gradient"] = gradient
+            print(msgpack.packb(response))
+        else:
+            print("AvogadroGradient:")
+            for atom in mol.atoms:
+                grad = ff.GetGradient(atom.OBAtom)
+                print(-1.0*grad.GetX(), -1.0*grad.GetY(), -1.0*grad.GetZ())
 
 
 
diff --git a/avogadro/qtplugins/forcefield/scripts/uff.py b/avogadro/qtplugins/forcefield/scripts/uff.py
index 6c5c926be5..d2efc1209b 100644
--- a/avogadro/qtplugins/forcefield/scripts/uff.py
+++ b/avogadro/qtplugins/forcefield/scripts/uff.py
@@ -5,6 +5,12 @@
 import json
 import sys
 
+try:
+    import msgpack
+    msgpack_available = True
+except ImportError:
+    msgpack_available = False
+
 try:
     from openbabel import pybel
     import numpy as np
@@ -30,6 +36,8 @@ def getMetaData():
         "ion": False,
         "radical": False,
     }
+    if (msgpack_available):
+        metaData["msgpack"] = True
     return metaData
 
 
@@ -48,23 +56,42 @@ def run(filename):
     num_atoms = len(mol.atoms)
     while True:
         # read new coordinates from stdin
-        for i in range(num_atoms):
-            coordinates = np.fromstring(input(), sep=" ")
-            atom = mol.atoms[i]
-            atom.OBAtom.SetVector(coordinates[0], coordinates[1], coordinates[2])
+        if (msgpack_available):
+            # unpack the coordinates
+            data = msgpack.unpackb(sys.stdin.buffer.read())
+            np_coords = np.array(data["coordinates"], dtype=float).reshape(-1, 3)
+            for i in range(num_atoms):
+                atom = mol.atoms[i]
+                atom.OBAtom.SetVector(np_coords[i][0], np_coords[i][1], np_coords[i][2])
+        else:
+            for i in range(num_atoms):
+                coordinates = np.fromstring(input(), sep=" ")
+                atom = mol.atoms[i]
+                atom.OBAtom.SetVector(coordinates[0], coordinates[1], coordinates[2])
 
         # update the molecule geometry for the next energy
         ff.SetCoordinates(mol.OBMol)
 
         # first print the energy of these coordinates
         energy = ff.Energy(True)  # in kJ/mol
-        print("AvogadroEnergy:", energy)  # in kJ/mol
+        if (msgpack_available):
+            response = {"energy": energy}
+        else:
+            print("AvogadroEnergy:", energy)  # in kJ/mol
 
         # now print the gradient on each atom
-        print("AvogadroGradient:")
-        for atom in mol.atoms:
-            grad = ff.GetGradient(atom.OBAtom)
-            print(-1.0*grad.GetX(), -1.0*grad.GetY(), -1.0*grad.GetZ())
+        if (msgpack_available):
+            gradient = []
+            for atom in mol.atoms:
+                grad = ff.GetGradient(atom.OBAtom)
+                gradient.append([-1.0*grad.GetX(), -1.0*grad.GetY(), -1.0*grad.GetZ()])
+            response["gradient"] = gradient
+            print(msgpack.packb(response))
+        else:
+            print("AvogadroGradient:")
+            for atom in mol.atoms:
+                grad = ff.GetGradient(atom.OBAtom)
+                print(-1.0*grad.GetX(), -1.0*grad.GetY(), -1.0*grad.GetZ())
 
 
 if __name__ == "__main__":