diff --git a/src/editor/ConfigObj.js b/src/editor/ConfigObj.js
index f4095ba6..142740c9 100644
--- a/src/editor/ConfigObj.js
+++ b/src/editor/ConfigObj.js
@@ -175,8 +175,7 @@ export default class ConfigObj {
       'ext-eyedropper',
       'ext-grid',
       'ext-imagelib',
-      // 'ext-arrows',
-      // 'ext-markers',
+      'ext-markers',
       'ext-overview_window',
       'ext-panning',
       'ext-shapes',
diff --git a/src/editor/extensions/ext-markers/ext-markers.js b/src/editor/extensions/ext-markers/ext-markers.js
new file mode 100644
index 00000000..857a3365
--- /dev/null
+++ b/src/editor/extensions/ext-markers/ext-markers.js
@@ -0,0 +1,340 @@
+/**
+ * @file ext-markers.js
+ *
+ * @license Apache-2.0
+ *
+ * @copyright 2010 Will Schleter based on ext-arrows.js by Copyright(c) 2010 Alexis Deveria
+ * @copyright 2021 OptimistikSAS
+ *
+ * This extension provides for the addition of markers to the either end
+ * or the middle of a line, polyline, path, polygon.
+ *
+ * Markers are graphics
+ *
+ * to simplify the coding and make the implementation as robust as possible,
+ * markers are not shared - every object has its own set of markers.
+ * this relationship is maintained by a naming convention between the
+ * ids of the markers and the ids of the object
+ *
+ * The following restrictions exist for simplicty of use and programming
+ *    objects and their markers to have the same color
+ *    marker size is fixed
+ *    an application specific attribute - se_type - is added to each marker element
+ *        to store the type of marker
+ *
+ * @todo
+ *    remove some of the restrictions above
+ *
+*/
+
+const loadExtensionTranslation = async function (lang) {
+  let translationModule;
+  try {
+    // eslint-disable-next-line no-unsanitized/method
+    translationModule = await import(`./locale/${encodeURIComponent(lang)}.js`);
+  } catch (_error) {
+    // eslint-disable-next-line no-console
+    console.error(`Missing translation (${lang}) - using 'en'`);
+    translationModule = await import(`./locale/en.js`);
+  }
+  return translationModule.default;
+};
+
+export default {
+  name: 'markers',
+  async init (S) {
+    const svgEditor = this;
+    const strings = await loadExtensionTranslation(svgEditor.configObj.pref('lang'));
+    const { svgCanvas } = svgEditor;
+    const { $id, addSVGElementFromJson: addElem } = svgCanvas;
+    const mtypes = [ 'start', 'mid', 'end' ];
+
+    // note - to add additional marker types add them below with a unique id
+    // and add the associated icon(s) to marker-icons.svg
+    // the geometry is normalized to a 100x100 box with the origin at lower left
+    // Safari did not like negative values for low left of viewBox
+    // remember that the coordinate system has +y downward
+    const markerTypes = {
+      nomarker: {},
+      leftarrow:
+        { element: 'path', attr: { d: 'M0,50 L100,90 L70,50 L100,10 Z' } },
+      rightarrow:
+        { element: 'path', attr: { d: 'M100,50 L0,90 L30,50 L0,10 Z' } },
+      box:
+        { element: 'path', attr: { d: 'M20,20 L20,80 L80,80 L80,20 Z' } },
+      mcircle:
+        { element: 'circle', attr: { r: 30, cx: 50, cy: 50 } }
+    };
+
+    // duplicate shapes to support unfilled (open) marker types with an _o suffix
+    [ 'leftarrow', 'rightarrow', 'box', 'mcircle' ].forEach((v) => {
+      markerTypes[v + '_o'] = markerTypes[v];
+    });
+
+    /**
+    * @param {Element} elem - A graphic element will have an attribute like marker-start
+    * @param {"marker-start"|"marker-mid"|"marker-end"} attr
+    * @returns {Element} The marker element that is linked to the graphic element
+    */
+    const getLinked  = (elem, attr) => {
+      const str = elem.getAttribute(attr);
+      if (!str) { return null; }
+      const m = str.match(/\(#(.*)\)/);
+      if (!m || m.length !== 2) {
+        return null;
+      }
+      return svgCanvas.getElem(m[1]);
+    };
+
+    let selElems;
+    /**
+     * Toggles context tool panel off/on.
+     * @param {boolean} on
+     * @returns {void}
+    */
+    const showPanel = (on) => {
+      $id('marker_panel').style.display = (on) ? 'block' : 'none';
+    };
+
+    /**
+    * @param {string} id
+    * @param {""|"\\nomarker"|"nomarker"|"leftarrow"|"rightarrow"|"textmarker"|"forwardslash"|"reverseslash"|"verticalslash"|"box"|"star"|"xmark"|"triangle"|"mcircle"} seType
+    * @returns {SVGMarkerElement}
+    */
+    const addMarker = (id, seType) => {
+      let marker = svgCanvas.getElem(id);
+      if (marker) { return undefined; }
+      if (seType === '' || seType === '\\nomarker') { return undefined; }
+
+      const el = selElems[0];
+      const color = el.getAttribute('stroke');
+      const strokeWidth = 10;
+      const refX = 50;
+      const refY = 50;
+      const viewBox = '0 0 100 100';
+      const markerWidth = 5;
+      const markerHeight = 5;
+
+      if (!markerTypes[seType]) {
+        console.error(`unknown marker type: ${seType}`);
+        return undefined;
+      }
+
+      // create a generic marker
+      marker = addElem({
+        element: 'marker',
+        attr: {
+          id,
+          markerUnits: 'strokeWidth',
+          orient: 'auto',
+          style: 'pointer-events:none',
+          se_type: seType
+        }
+      });
+
+      const mel = addElem(markerTypes[seType]);
+      const fillcolor = (seType.substr(-2) === '_o')
+        ? 'none'
+        : color;
+
+      mel.setAttribute('fill', fillcolor);
+      mel.setAttribute('stroke', color);
+      mel.setAttribute('stroke-width', strokeWidth);
+      marker.append(mel);
+
+      marker.setAttribute('viewBox', viewBox);
+      marker.setAttribute('markerWidth', markerWidth);
+      marker.setAttribute('markerHeight', markerHeight);
+      marker.setAttribute('refX', refX);
+      marker.setAttribute('refY', refY);
+      svgCanvas.findDefs().append(marker);
+
+      return marker;
+    };
+
+    /**
+    * @param {Element} elem
+    * @returns {SVGPolylineElement}
+    */
+    const convertline = (elem) => {
+      // this routine came from the connectors extension
+      // it is needed because midpoint markers don't work with line elements
+      if (elem.tagName !== 'line') { return elem; }
+
+      // Convert to polyline to accept mid-arrow
+
+      const x1 = Number(elem.getAttribute('x1'));
+      const x2 = Number(elem.getAttribute('x2'));
+      const y1 = Number(elem.getAttribute('y1'));
+      const y2 = Number(elem.getAttribute('y2'));
+      const { id } = elem;
+
+      const midPt = (' ' + ((x1 + x2) / 2) + ',' + ((y1 + y2) / 2) + ' ');
+      const pline = addElem({
+        element: 'polyline',
+        attr: {
+          points: (x1 + ',' + y1 + midPt + x2 + ',' + y2),
+          stroke: elem.getAttribute('stroke'),
+          'stroke-width': elem.getAttribute('stroke-width'),
+          fill: 'none',
+          opacity: elem.getAttribute('opacity') || 1
+        }
+      });
+      mtypes.forEach((pos) => { // get any existing marker definitions
+        const nam = 'marker-' + pos;
+        const m = elem.getAttribute(nam);
+        if (m) { pline.setAttribute(nam, elem.getAttribute(nam)); }
+      });
+
+      const batchCmd = new S.BatchCommand();
+      batchCmd.addSubCommand(new S.RemoveElementCommand(elem, elem.parentNode));
+      batchCmd.addSubCommand(new S.InsertElementCommand(pline));
+
+      elem.insertAdjacentElement('afterend', pline);
+      elem.remove();
+      svgCanvas.clearSelection();
+      pline.id = id;
+      svgCanvas.addToSelection([ pline ]);
+      S.addCommandToHistory(batchCmd);
+      return pline;
+    };
+
+    /**
+    *
+    * @returns {void}
+    */
+    const setMarker = (pos, markerType) => {
+      if (!selElems) return;
+      const markerName = 'marker-' + pos;
+      const el = selElems[0];
+      const marker = getLinked(el, markerName);
+      if (marker) { marker.remove(); }
+      el.removeAttribute(markerName);
+      let val = markerType;
+      if (val === '') { val = '\\nomarker'; }
+      if (val === '\\nomarker') {
+        svgCanvas.call('changed', selElems);
+        return;
+      }
+      // Set marker on element
+      const id = 'mkr_' + pos + '_' + el.id;
+      addMarker(id, val);
+      svgCanvas.changeSelectedAttribute(markerName, 'url(#' + id + ')');
+      if (el.tagName === 'line' && pos === 'mid') {
+        convertline(el);
+      }
+      svgCanvas.call('changed', selElems);
+    };
+
+    /**
+     * Called when the main system modifies an object. This routine changes
+     *   the associated markers to be the same color.
+     * @param {Element} elem
+     * @returns {void}
+    */
+    const colorChanged = (elem) => {
+      const color = elem.getAttribute('stroke');
+
+      mtypes.forEach((pos) => {
+        const marker = getLinked(elem, 'marker-' + pos);
+        if (!marker) { return; }
+        if (!marker.attributes.se_type) { return; } // not created by this extension
+        const ch = marker.lastElementChild;
+        if (!ch) { return; }
+        const curfill = ch.getAttribute('fill');
+        const curstroke = ch.getAttribute('stroke');
+        if (curfill && curfill !== 'none') { ch.setAttribute('fill', color); }
+        if (curstroke && curstroke !== 'none') { ch.setAttribute('stroke', color); }
+      });
+    };
+
+    /**
+    * Called when the main system creates or modifies an object.
+    * Its primary purpose is to create new markers for cloned objects.
+    * @param {Element} el
+    * @returns {void}
+    */
+    const updateReferences = (el) => {
+      mtypes.forEach((pos) => {
+        const id = 'mkr_' + pos + '_' + el.id;
+        const markerName = 'marker-' + pos;
+        const marker = getLinked(el, markerName);
+        if (!marker || !marker.attributes.se_type) { return; } // not created by this extension
+        const url = el.getAttribute(markerName);
+        if (url) {
+          const len = el.id.length;
+          const linkid = url.substr(-len - 1, len);
+          if (el.id !== linkid) {
+            const val = $id(pos + '_marker').getAttribute('value');
+            addMarker(id, val);
+            svgCanvas.changeSelectedAttribute(markerName, 'url(#' + id + ')');
+            if (el.tagName === 'line' && pos === 'mid') { el = convertline(el); }
+            svgCanvas.call('changed', selElems);
+          }
+        }
+      });
+    };
+
+    return {
+      name: svgEditor.i18next.t(`${name}:name`),
+      // The callback should be used to load the DOM with the appropriate UI items
+      callback() {
+        // Add the context panel and its handler(s)
+        const panelTemplate = document.createElement("template");
+        let innerHTML = '<div id="marker_panel">';
+        mtypes.forEach((pos) => {
+          innerHTML += `<se-list id="${pos}_marker_list_opts" title="tools.${pos}_marker_list_opts" label="" width="22px" height="22px">`;
+          Object.entries(markerTypes).forEach(([ marker, _mkr ]) => {
+            innerHTML += `<se-list-item id="mkr_${pos}_${marker}" value="${marker}" title="tools.mkr_${marker}" src="${marker}.svg" img-height="22px"></se-list-item>`;
+          });
+          innerHTML += '</se-list>';
+        });
+        innerHTML += '</div>';
+        // eslint-disable-next-line no-unsanitized/property
+        panelTemplate.innerHTML = innerHTML;
+        $id("tools_top").appendChild(panelTemplate.content.cloneNode(true));
+        mtypes.forEach((pos) => {
+          $id(`${pos}_marker_list_opts`).addEventListener('change', (evt) => {
+            setMarker(pos, evt.detail.value);
+          });
+        });
+        // don't display the panels on start
+        showPanel(false);
+      },
+      /* async */ addLangData ({ _importLocale, _lang }) {
+        return { data: strings.langList };
+      },
+      selectedChanged (opts) {
+        // Use this to update the current selected elements
+        selElems = opts.elems;
+
+        const markerElems = [ 'line', 'path', 'polyline', 'polygon' ];
+
+        let i = selElems.length;
+        while (i--) {
+          const elem = selElems[i];
+          if (elem && markerElems.includes(elem.tagName)) {
+            if (opts.selectedElement && !opts.multiselected) {
+              showPanel(true);
+            } else {
+              showPanel(false);
+            }
+          } else {
+            showPanel(false);
+          }
+        }
+      },
+      elementChanged (opts) {
+        const elem = opts.elems[0];
+        if (elem && (
+          elem.getAttribute('marker-start') ||
+          elem.getAttribute('marker-mid') ||
+          elem.getAttribute('marker-end')
+        )) {
+          colorChanged(elem);
+          updateReferences(elem);
+        }
+      }
+    };
+  }
+};
diff --git a/src/editor/extensions/ext-markers/locale/en.js b/src/editor/extensions/ext-markers/locale/en.js
new file mode 100644
index 00000000..1bb5686b
--- /dev/null
+++ b/src/editor/extensions/ext-markers/locale/en.js
@@ -0,0 +1,46 @@
+export default {
+  name: 'Markers',
+  langList: [
+    { id: 'nomarker', title: 'No Marker' },
+    { id: 'leftarrow', title: 'Left Arrow' },
+    { id: 'rightarrow', title: 'Right Arrow' },
+    { id: 'textmarker', title: 'Text Marker' },
+    { id: 'forwardslash', title: 'Forward Slash' },
+    { id: 'reverseslash', title: 'Reverse Slash' },
+    { id: 'verticalslash', title: 'Vertical Slash' },
+    { id: 'box', title: 'Box' },
+    { id: 'star', title: 'Star' },
+    { id: 'xmark', title: 'X' },
+    { id: 'triangle', title: 'Triangle' },
+    { id: 'mcircle', title: 'Circle' },
+    { id: 'leftarrow_o', title: 'Open Left Arrow' },
+    { id: 'rightarrow_o', title: 'Open Right Arrow' },
+    { id: 'box_o', title: 'Open Box' },
+    { id: 'star_o', title: 'Open Star' },
+    { id: 'triangle_o', title: 'Open Triangle' },
+    { id: 'mcircle_o', title: 'Open Circle' }
+  ],
+  contextTools: [
+    {
+      title: 'Start marker',
+      label: 's'
+    },
+    {
+      title: 'Select start marker type'
+    },
+    {
+      title: 'Middle marker',
+      label: 'm'
+    },
+    {
+      title: 'Select mid marker type'
+    },
+    {
+      title: 'End marker',
+      label: 'e'
+    },
+    {
+      title: 'Select end marker type'
+    }
+  ]
+};
diff --git a/src/editor/extensions/ext-markers/locale/zh-CN.js b/src/editor/extensions/ext-markers/locale/zh-CN.js
new file mode 100755
index 00000000..9b614ba5
--- /dev/null
+++ b/src/editor/extensions/ext-markers/locale/zh-CN.js
@@ -0,0 +1,46 @@
+export default {
+  name: '标记',
+  langList: [
+    { id: 'nomarker', title: '无标记' },
+    { id: 'leftarrow', title: '左箭头' },
+    { id: 'rightarrow', title: '右箭头' },
+    { id: 'textmarker', title: '文本' },
+    { id: 'forwardslash', title: '斜杠' },
+    { id: 'reverseslash', title: '反斜杠' },
+    { id: 'verticalslash', title: '垂直线' },
+    { id: 'box', title: '方块' },
+    { id: 'star', title: '星形' },
+    { id: 'xmark', title: 'X' },
+    { id: 'triangle', title: '三角形' },
+    { id: 'mcircle', title: '圆形' },
+    { id: 'leftarrow_o', title: '左箭头(空心)' },
+    { id: 'rightarrow_o', title: '右箭头(空心)' },
+    { id: 'box_o', title: '方块(空心)' },
+    { id: 'star_o', title: '星形(空心)' },
+    { id: 'triangle_o', title: '三角形(空心)' },
+    { id: 'mcircle_o', title: '圆形(空心)' }
+  ],
+  contextTools: [
+    {
+      title: '起始标记',
+      label: 's'
+    },
+    {
+      title: '选择起始标记类型'
+    },
+    {
+      title: '中段标记',
+      label: 'm'
+    },
+    {
+      title: '选择中段标记类型'
+    },
+    {
+      title: '末端标记',
+      label: 'e'
+    },
+    {
+      title: '选择末端标记类型'
+    }
+  ]
+};
diff --git a/src/editor/extensions/ext-polystar/ext-polystar.js b/src/editor/extensions/ext-polystar/ext-polystar.js
index b93f909e..cee59068 100644
--- a/src/editor/extensions/ext-polystar/ext-polystar.js
+++ b/src/editor/extensions/ext-polystar/ext-polystar.js
@@ -449,9 +449,6 @@ export default {
             showPanel(false, "polygon");
           }
         }
-      },
-      elementChanged(_opts) {
-        // const elem = opts.elems[0];
       }
     };
   }
diff --git a/src/svgcanvas/sanitize.js b/src/svgcanvas/sanitize.js
index 8544ca4f..b24402e1 100644
--- a/src/svgcanvas/sanitize.js
+++ b/src/svgcanvas/sanitize.js
@@ -42,7 +42,7 @@ const svgWhiteList_ = {
   image: [  'clip-path', 'clip-rule', 'filter', 'height',  'mask', 'opacity', 'requiredFeatures', 'systemLanguage', 'width', 'x', 'xlink:href', 'xlink:title', 'y' ],
   line: [  'clip-path', 'clip-rule', 'fill', 'fill-opacity', 'fill-rule', 'filter',  'marker-end', 'marker-mid', 'marker-start', 'mask', 'opacity', 'requiredFeatures', 'stroke', 'stroke-dasharray', 'stroke-dashoffset', 'stroke-linecap', 'stroke-linejoin', 'stroke-miterlimit', 'stroke-opacity', 'stroke-width', 'systemLanguage', 'x1', 'x2', 'y1', 'y2' ],
   linearGradient: [   'gradientTransform', 'gradientUnits', 'requiredFeatures', 'spreadMethod', 'systemLanguage', 'x1', 'x2', 'xlink:href', 'y1', 'y2' ],
-  marker: [   'markerHeight', 'markerUnits', 'markerWidth', 'orient', 'preserveAspectRatio', 'refX', 'refY', 'systemLanguage', 'viewBox' ],
+  marker: [   'markerHeight', 'markerUnits', 'markerWidth', 'orient', 'preserveAspectRatio', 'refX', 'refY', 'se_type', 'systemLanguage', 'viewBox' ],
   mask: [  'height',  'maskContentUnits', 'maskUnits', 'width', 'x', 'y' ],
   metadata: [ ],
   path: [  'clip-path', 'clip-rule', 'd', 'enable-background', 'fill', 'fill-opacity', 'fill-rule', 'filter',  'marker-end', 'marker-mid', 'marker-start', 'mask', 'opacity', 'requiredFeatures', 'stroke', 'stroke-dasharray', 'stroke-dashoffset', 'stroke-linecap', 'stroke-linejoin', 'stroke-miterlimit', 'stroke-opacity', 'stroke-width', 'systemLanguage' ],