diff --git a/src/ApplicationController.cpp b/src/ApplicationController.cpp
index df5d95a..43ae3d9 100644
--- a/src/ApplicationController.cpp
+++ b/src/ApplicationController.cpp
@@ -3,6 +3,7 @@
 #include "SketchFeature.h"
 #include "SketchLine.h"
 #include "SketchRectangle.h"
+#include "SketchCircle.h"
 #include "MainWindow.h"
 
 #include <QInputDialog>
@@ -148,6 +149,13 @@ void ApplicationController::addRectangle(const gp_Pnt& corner1, const gp_Pnt& co
     }
 }
 
+void ApplicationController::addCircle(const gp_Pnt& center, double radius)
+{
+    if (m_activeSketch) {
+        m_activeSketch->addObject(new SketchCircle(center, radius));
+    }
+}
+
 void ApplicationController::endSketch()
 {
     m_activeSketch = nullptr;
diff --git a/src/ApplicationController.h b/src/ApplicationController.h
index 5ede770..cc9ca80 100644
--- a/src/ApplicationController.h
+++ b/src/ApplicationController.h
@@ -33,6 +33,7 @@ public slots:
     void setActiveTool(ToolType tool);
     void addLine(const gp_Pnt& start, const gp_Pnt& end);
     void addRectangle(const gp_Pnt& corner1, const gp_Pnt& corner2);
+    void addCircle(const gp_Pnt& center, double radius);
     void newDocument();
     bool openDocument();
     bool saveDocument();
diff --git a/src/MainWindow.cpp b/src/MainWindow.cpp
index a2d09b0..b835cb6 100644
--- a/src/MainWindow.cpp
+++ b/src/MainWindow.cpp
@@ -147,6 +147,7 @@ MainWindow::MainWindow(ApplicationController* appController, QWidget *parent)
 
     connect(m_viewport, &ViewportWidget::lineAdded, m_appController, &ApplicationController::addLine);
     connect(m_viewport, &ViewportWidget::rectangleAdded, m_appController, &ApplicationController::addRectangle);
+    connect(m_viewport, &ViewportWidget::circleAdded, m_appController, &ApplicationController::addCircle);
     connect(m_viewport, &ViewportWidget::planeSelected, m_appController, &ApplicationController::onPlaneSelected);
     connect(m_viewport, &ViewportWidget::toolDeactivated, m_appController, [this]() { m_appController->setActiveTool(ApplicationController::ToolType::None); });
 
diff --git a/src/SketchCircle.cpp b/src/SketchCircle.cpp
new file mode 100644
index 0000000..4e94f7b
--- /dev/null
+++ b/src/SketchCircle.cpp
@@ -0,0 +1,56 @@
+#include "SketchCircle.h"
+#include <QJsonArray>
+
+namespace
+{
+    void pointToJson(const gp_Pnt& p, QJsonArray& arr)
+    {
+        arr.append(p.X());
+        arr.append(p.Y());
+        arr.append(p.Z());
+    }
+
+    gp_Pnt jsonToPoint(const QJsonArray& arr)
+    {
+        return gp_Pnt(arr[0].toDouble(), arr[1].toDouble(), arr[2].toDouble());
+    }
+}
+
+SketchCircle::SketchCircle() : m_radius(0.0)
+{
+}
+
+SketchCircle::SketchCircle(const gp_Pnt& center, double radius)
+    : m_center(center), m_radius(radius)
+{
+}
+
+SketchObject::ObjectType SketchCircle::type() const
+{
+    return ObjectType::Circle;
+}
+
+void SketchCircle::read(const QJsonObject& json)
+{
+    m_center = jsonToPoint(json["center"].toArray());
+    m_radius = json["radius"].toDouble();
+}
+
+void SketchCircle::write(QJsonObject& json) const
+{
+    QJsonArray centerArr;
+    pointToJson(m_center, centerArr);
+    json["center"] = centerArr;
+    json["radius"] = m_radius;
+    json["type"] = "Circle";
+}
+
+const gp_Pnt& SketchCircle::center() const
+{
+    return m_center;
+}
+
+double SketchCircle::radius() const
+{
+    return m_radius;
+}
diff --git a/src/SketchCircle.h b/src/SketchCircle.h
new file mode 100644
index 0000000..04089fe
--- /dev/null
+++ b/src/SketchCircle.h
@@ -0,0 +1,26 @@
+#ifndef SKETCHCIRCLE_H
+#define SKETCHCIRCLE_H
+
+#include "SketchObject.h"
+#include <gp_Pnt.hxx>
+
+class SketchCircle : public SketchObject
+{
+public:
+    SketchCircle();
+    SketchCircle(const gp_Pnt& center, double radius);
+
+    ObjectType type() const override;
+
+    void read(const QJsonObject& json) override;
+    void write(QJsonObject& json) const override;
+
+    const gp_Pnt& center() const;
+    double radius() const;
+
+private:
+    gp_Pnt m_center;
+    double m_radius;
+};
+
+#endif // SKETCHCIRCLE_H
diff --git a/src/SketchObject.h b/src/SketchObject.h
index c7a356c..d2346e5 100644
--- a/src/SketchObject.h
+++ b/src/SketchObject.h
@@ -8,7 +8,8 @@ class SketchObject
 public:
     enum class ObjectType {
         Line,
-        Rectangle
+        Rectangle,
+        Circle
     };
 
     SketchObject() = default;
diff --git a/src/ViewportWidget.cpp b/src/ViewportWidget.cpp
index 2170beb..734289e 100644
--- a/src/ViewportWidget.cpp
+++ b/src/ViewportWidget.cpp
@@ -8,10 +8,12 @@
 #include "SketchFeature.h"
 #include "SketchLine.h"
 #include "SketchRectangle.h"
+#include "SketchCircle.h"
 #include "SketchObject.h"
 #include "ApplicationController.h"
 #include "RectangleTool.h"
 #include "LineTool.h"
+#include "CircleTool.h"
 #include <QMouseEvent>
 #include <QKeyEvent>
 #include <QWheelEvent>
@@ -61,6 +63,7 @@ ViewportWidget::ViewportWidget(QWidget *parent)
 
     m_sketchTools.insert(static_cast<int>(ApplicationController::ToolType::Line), new LineTool(this));
     m_sketchTools.insert(static_cast<int>(ApplicationController::ToolType::Rectangle), new RectangleTool(this));
+    m_sketchTools.insert(static_cast<int>(ApplicationController::ToolType::Circle), new CircleTool(this));
 
     m_snapping = new Snapping(this);
 }
@@ -511,6 +514,39 @@ void ViewportWidget::drawSketch(const SketchFeature* sketch)
 
             vertexCounts[start]++;
             vertexCounts[end]++;
+        } else if (obj->type() == SketchObject::ObjectType::Circle) {
+            auto circle = static_cast<const SketchCircle*>(obj);
+            const auto& center = circle->center();
+            double radius = circle->radius();
+            QVector3D centerPos(center.X(), center.Y(), center.Z());
+
+            const int numSegments = 64;
+            QVector3D u_axis, v_axis;
+            switch (sketch->plane()) {
+                case SketchFeature::SketchPlane::XY:
+                    u_axis = QVector3D(1, 0, 0);
+                    v_axis = QVector3D(0, 1, 0);
+                    break;
+                case SketchFeature::SketchPlane::XZ:
+                    u_axis = QVector3D(1, 0, 0);
+                    v_axis = QVector3D(0, 0, 1);
+                    break;
+                case SketchFeature::SketchPlane::YZ:
+                    u_axis = QVector3D(0, 1, 0);
+                    v_axis = QVector3D(0, 0, 1);
+                    break;
+            }
+
+            for (int i = 0; i < numSegments; ++i) {
+                double angle1 = 2.0 * M_PI * double(i) / double(numSegments);
+                QVector3D p1 = centerPos + radius * (cos(angle1) * u_axis + sin(angle1) * v_axis);
+
+                double angle2 = 2.0 * M_PI * double(i + 1) / double(numSegments);
+                QVector3D p2 = centerPos + radius * (cos(angle2) * u_axis + sin(angle2) * v_axis);
+
+                lineVertices << p1.x() << p1.y() << p1.z();
+                lineVertices << p2.x() << p2.y() << p2.z();
+            }
         } else if (obj->type() == SketchObject::ObjectType::Rectangle) {
             auto rect = static_cast<const SketchRectangle*>(obj);
             const auto& p1 = rect->corner1();
diff --git a/src/ViewportWidget.h b/src/ViewportWidget.h
index e67c0c8..2b2420d 100644
--- a/src/ViewportWidget.h
+++ b/src/ViewportWidget.h
@@ -70,6 +70,7 @@ public slots:
 signals:
     void lineAdded(const gp_Pnt& start, const gp_Pnt& end);
     void rectangleAdded(const gp_Pnt& corner1, const gp_Pnt& corner2);
+    void circleAdded(const gp_Pnt& center, double radius);
     void planeSelected(SketchPlane plane);
     void toolDeactivated();