diff --git a/client/constants.js b/client/constants.js
index c2e6c5be..a4235717 100644
--- a/client/constants.js
+++ b/client/constants.js
@@ -82,5 +82,7 @@ export const SHOW_TOAST = 'SHOW_TOAST';
 export const HIDE_TOAST = 'HIDE_TOAST';
 export const SET_TOAST_TEXT = 'SET_TOAST_TEXT';
 
+export const SET_UNSAVED_CHANGES = 'SET_UNSAVED_CHANGES';
+
 // eventually, handle errors more specifically and better
 export const ERROR = 'ERROR';
diff --git a/client/modules/IDE/actions/ide.js b/client/modules/IDE/actions/ide.js
index d56ae836..05725fca 100644
--- a/client/modules/IDE/actions/ide.js
+++ b/client/modules/IDE/actions/ide.js
@@ -163,3 +163,10 @@ export function closeKeyboardShortcutModal() {
   };
 }
 
+export function setUnsavedChanges(value) {
+  return {
+    type: ActionTypes.SET_UNSAVED_CHANGES,
+    value
+  };
+}
+
diff --git a/client/modules/IDE/actions/project.js b/client/modules/IDE/actions/project.js
index 681829b9..d47f93c5 100644
--- a/client/modules/IDE/actions/project.js
+++ b/client/modules/IDE/actions/project.js
@@ -6,6 +6,7 @@ import JSZipUtils from 'jszip-utils';
 import { saveAs } from 'file-saver';
 import { getBlobUrl } from './files';
 import { showToast, setToastText } from './toast';
+import { setUnsavedChanges } from './ide';
 
 const ROOT_URL = location.href.indexOf('localhost') > 0 ? 'http://localhost:8000/api' : '/api';
 
@@ -32,6 +33,7 @@ export function getProject(id) {
           owner: response.data.user
         });
         getProjectBlobUrls()(dispatch, getState);
+        dispatch(setUnsavedChanges(false));
       })
       .catch(response => dispatch({
         type: ActionTypes.ERROR,
@@ -58,6 +60,7 @@ export function saveProject(autosave) {
     if (state.project.id) {
       axios.put(`${ROOT_URL}/projects/${state.project.id}`, formParams, { withCredentials: true })
         .then(() => {
+          dispatch(setUnsavedChanges(false));
           dispatch({
             type: ActionTypes.PROJECT_SAVE_SUCCESS
           });
@@ -73,6 +76,7 @@ export function saveProject(autosave) {
     } else {
       axios.post(`${ROOT_URL}/projects`, formParams, { withCredentials: true })
         .then(response => {
+          dispatch(setUnsavedChanges(false));
           browserHistory.push(`/projects/${response.data.id}`);
           dispatch({
             type: ActionTypes.NEW_PROJECT,
@@ -112,6 +116,7 @@ export function createProject() {
           owner: response.data.user,
           files: response.data.files
         });
+        dispatch(setUnsavedChanges(false));
       })
       .catch(response => dispatch({
         type: ActionTypes.PROJECT_SAVE_FAIL,
diff --git a/client/modules/IDE/components/Editor.js b/client/modules/IDE/components/Editor.js
index 43379a4d..d035a104 100644
--- a/client/modules/IDE/components/Editor.js
+++ b/client/modules/IDE/components/Editor.js
@@ -60,33 +60,33 @@ class Editor extends React.Component {
         })
       }
     });
+
     this._cm.on('change', debounce(200, () => {
+      this.props.setUnsavedChanges(true);
       this.props.updateFileContent(this.props.file.name, this._cm.getValue());
     }));
+
     this._cm.on('keyup', () => {
       const temp = `line ${parseInt((this._cm.getCursor().line) + 1, 10)}`;
       document.getElementById('current-line').innerHTML = temp;
     });
-    // this._cm.on('change', () => { // eslint-disable-line
-    //   // this.props.updateFileContent('sketch.js', this._cm.getValue());
-    //   throttle(1000, () => console.log('debounce is working!'));
-    //   this.props.updateFileContent(this.props.file.name, this._cm.getValue());
-    // });
-    this._cm.getWrapperElement().style['font-size'] = `${this.props.fontSize}px`;
-    this._cm.setOption('indentWithTabs', this.props.isTabIndent);
-    this._cm.setOption('tabSize', this.props.indentationAmount);
 
     this._cm.on('keydown', (_cm, e) => {
       if (e.key === 'Tab' && e.shiftKey) {
         this.tidyCode();
       }
     });
+
+    this._cm.getWrapperElement().style['font-size'] = `${this.props.fontSize}px`;
+    this._cm.setOption('indentWithTabs', this.props.isTabIndent);
+    this._cm.setOption('tabSize', this.props.indentationAmount);
   }
 
   componentDidUpdate(prevProps) {
     if (this.props.file.content !== prevProps.file.content &&
         this.props.file.content !== this._cm.getValue()) {
       this._cm.setValue(this.props.file.content); // eslint-disable-line no-underscore-dangle
+      setTimeout(() => this.props.setUnsavedChanges(false), 500);
     }
     if (this.props.fontSize !== prevProps.fontSize) {
       this._cm.getWrapperElement().style['font-size'] = `${this.props.fontSize}px`;
@@ -190,7 +190,8 @@ Editor.propTypes = {
   editorOptionsVisible: PropTypes.bool.isRequired,
   showEditorOptions: PropTypes.func.isRequired,
   closeEditorOptions: PropTypes.func.isRequired,
-  showKeyboardShortcutModal: PropTypes.func.isRequired
+  showKeyboardShortcutModal: PropTypes.func.isRequired,
+  setUnsavedChanges: PropTypes.func.isRequired
 };
 
 export default Editor;
diff --git a/client/modules/IDE/pages/IDEView.js b/client/modules/IDE/pages/IDEView.js
index 5c1ffc1d..a95249fd 100644
--- a/client/modules/IDE/pages/IDEView.js
+++ b/client/modules/IDE/pages/IDEView.js
@@ -14,6 +14,7 @@ import Console from '../components/Console';
 import Toast from '../components/Toast';
 import { bindActionCreators } from 'redux';
 import { connect } from 'react-redux';
+import { withRouter } from 'react-router';
 import * as FileActions from '../actions/files';
 import * as IDEActions from '../actions/ide';
 import * as ProjectActions from '../actions/project';
@@ -33,6 +34,7 @@ class IDEView extends React.Component {
     this._handleConsolePaneOnDragFinished = this._handleConsolePaneOnDragFinished.bind(this);
     this._handleSidebarPaneOnDragFinished = this._handleSidebarPaneOnDragFinished.bind(this);
     this.handleGlobalKeydown = this.handleGlobalKeydown.bind(this);
+    this.warnIfUnsavedChanges = this.warnIfUnsavedChanges.bind(this);
   }
 
   componentDidMount() {
@@ -55,6 +57,10 @@ class IDEView extends React.Component {
 
     this.isMac = navigator.userAgent.toLowerCase().indexOf('mac') !== -1;
     document.addEventListener('keydown', this.handleGlobalKeydown, false);
+
+    this.props.router.setRouteLeaveHook(this.props.route, () => this.warnIfUnsavedChanges());
+
+    window.onbeforeunload = () => this.warnIfUnsavedChanges();
   }
 
   componentWillUpdate(nextProps) {
@@ -91,6 +97,10 @@ class IDEView extends React.Component {
       clearInterval(this.autosaveInterval);
       this.autosaveInterval = null;
     }
+
+    if (this.props.route.path !== prevProps.route.path) {
+      this.props.router.setRouteLeaveHook(this.props.route, () => this.warnIfUnsavedChanges());
+    }
   }
 
   componentWillUnmount() {
@@ -134,6 +144,17 @@ class IDEView extends React.Component {
     }
   }
 
+  warnIfUnsavedChanges() { // eslint-disable-line
+    if (this.props.ide.unsavedChanges
+      && ((this.props.project.owner && this.props.project.owner.id === this.props.user.id)
+      || (!this.props.project.owner))) {
+      if (!window.confirm('Are you sure you want to leave this page? You have unsaved changes.')) {
+        return false;
+      }
+      this.props.setUnsavedChanges(false);
+    }
+  }
+
   render() {
     return (
       <div className="ide">
@@ -243,6 +264,7 @@ class IDEView extends React.Component {
                   showEditorOptions={this.props.showEditorOptions}
                   closeEditorOptions={this.props.closeEditorOptions}
                   showKeyboardShortcutModal={this.props.showKeyboardShortcutModal}
+                  setUnsavedChanges={this.props.setUnsavedChanges}
                 />
                 <Console
                   consoleEvent={this.props.ide.consoleEvent}
@@ -380,7 +402,8 @@ IDEView.propTypes = {
     newFolderModalVisible: PropTypes.bool.isRequired,
     shareModalVisible: PropTypes.bool.isRequired,
     editorOptionsVisible: PropTypes.bool.isRequired,
-    keyboardShortcutVisible: PropTypes.bool.isRequired
+    keyboardShortcutVisible: PropTypes.bool.isRequired,
+    unsavedChanges: PropTypes.bool.isRequired
   }).isRequired,
   startSketch: PropTypes.func.isRequired,
   stopSketch: PropTypes.func.isRequired,
@@ -464,7 +487,12 @@ IDEView.propTypes = {
   }).isRequired,
   showToast: PropTypes.func.isRequired,
   setToastText: PropTypes.func.isRequired,
-  autosaveProject: PropTypes.func.isRequired
+  autosaveProject: PropTypes.func.isRequired,
+  router: PropTypes.shape({
+    setRouteLeaveHook: PropTypes.func
+  }).isRequired,
+  route: PropTypes.object.isRequired,
+  setUnsavedChanges: PropTypes.func.isRequired
 };
 
 function mapStateToProps(state) {
@@ -495,4 +523,4 @@ function mapDispatchToProps(dispatch) {
   dispatch);
 }
 
-export default connect(mapStateToProps, mapDispatchToProps)(IDEView);
+export default withRouter(connect(mapStateToProps, mapDispatchToProps)(IDEView));
diff --git a/client/modules/IDE/reducers/ide.js b/client/modules/IDE/reducers/ide.js
index 8d6d3a64..8d73f6a0 100644
--- a/client/modules/IDE/reducers/ide.js
+++ b/client/modules/IDE/reducers/ide.js
@@ -15,7 +15,8 @@ const initialState = {
   newFolderModalVisible: false,
   shareModalVisible: false,
   editorOptionsVisible: false,
-  keyboardShortcutVisible: false
+  keyboardShortcutVisible: false,
+  unsavedChanges: false
 };
 
 const ide = (state = initialState, action) => {
@@ -70,6 +71,8 @@ const ide = (state = initialState, action) => {
       return Object.assign({}, state, { keyboardShortcutVisible: true });
     case ActionTypes.CLOSE_KEYBOARD_SHORTCUT_MODAL:
       return Object.assign({}, state, { keyboardShortcutVisible: false });
+    case ActionTypes.SET_UNSAVED_CHANGES:
+      return Object.assign({}, state, { unsavedChanges: action.value });
     default:
       return state;
   }