diff --git a/.gitignore b/.gitignore
index 21f5caf..6d062db 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,4 +4,3 @@ downloads
 node_modules
 *.zip
 npm-debug.log
-yarn.lock
diff --git a/examples/_07_json_schema_validation.html b/examples/07_json_schema_validation.html
similarity index 92%
rename from examples/_07_json_schema_validation.html
rename to examples/07_json_schema_validation.html
index cbee05a..07d8f0c 100644
--- a/examples/_07_json_schema_validation.html
+++ b/examples/07_json_schema_validation.html
@@ -59,12 +59,14 @@
   }
 
   var options = {
-    schema: schema
+    modes: ['code', 'tree']
   }
 
   // create the editor
   var container = document.getElementById('jsoneditor')
-  var editor = jsoneditor(container, options, json)
+  var editor = jsoneditor(container, options)
+  editor.setSchema(schema)
+  editor.set(json)
 </script>
 </body>
 </html>
diff --git a/examples/08_custom_ace.html b/examples/08_custom_ace.html
index f5df411..a625f08 100644
--- a/examples/08_custom_ace.html
+++ b/examples/08_custom_ace.html
@@ -35,7 +35,7 @@
   var container = document.getElementById('jsoneditor')
   var options = {
     mode: 'code',
-    onLoadAce: function (aceEditor, container, options) {
+    onLoadAce: function (aceEditor, container) {
       // we can adjust configuration of the ace editor,
       // or create a completely new instance of ace editor.
 
diff --git a/src/components/Ace.js b/src/components/Ace.js
new file mode 100644
index 0000000..6e45ff1
--- /dev/null
+++ b/src/components/Ace.js
@@ -0,0 +1,99 @@
+import { h, Component } from 'preact'
+import ace from '../assets/ace'
+
+/**
+ * Usage:
+ *
+ *     <Ace value={"{}"}
+ *          ace={Object}
+ *          indentation={2}
+ *          onChange={function(value: String)}
+ *          onLoadAce={function(aceEditor, container)} />
+ *
+ */
+export default class Ace extends Component {
+  constructor (props) {
+    super(props)
+
+    this.aceEditor = null
+  }
+
+  render (props, state) {
+    return h('div', {id: this.id,  class: 'jsoneditor-code'})
+  }
+
+  shouldComponentUpdate () {
+    // always prevent rerendering, that would destroy the DOM of the Ace editor
+    return false
+  }
+
+  componentDidMount () {
+    const container = this.base
+
+    // use ace from bundle, and if not available
+    // try to use from options or else from global
+    const _ace = ace || this.props.ace || window['ace']
+
+    let aceEditor = null
+    if (_ace && _ace.edit) {
+      // create ace editor
+      aceEditor = _ace.edit(container)
+
+      // bundle and load jsoneditor theme for ace editor
+      require('../assets/ace/theme-jsoneditor')
+
+      // configure ace editor
+      aceEditor.$blockScrolling = Infinity
+      aceEditor.setTheme('ace/theme/jsoneditor')
+      aceEditor.setShowPrintMargin(false)
+      aceEditor.setFontSize(13)
+      aceEditor.getSession().setMode('ace/mode/json')
+      aceEditor.getSession().setTabSize(this.props.indentation || 2)
+      aceEditor.getSession().setUseSoftTabs(true)
+      aceEditor.getSession().setUseWrapMode(true)
+      aceEditor.commands.bindKey('Ctrl-L', null)    // disable Ctrl+L (is used by the browser to select the address bar)
+      aceEditor.commands.bindKey('Command-L', null) // disable Ctrl+L (is used by the browser to select the address bar)
+    }
+    else {
+      // ace is excluded from the bundle.
+    }
+
+    // allow changing the config or completely replacing aceEditor
+    this.aceEditor = this.props.onLoadAce
+        ? this.props.onLoadAce(aceEditor, container) || aceEditor
+        : aceEditor
+
+    // register onchange event
+    this.aceEditor.on('change', this.handleChange)
+
+    // set value, the text contents for the editor
+    this.aceEditor.setValue(this.props.value || '', -1)
+  }
+
+  componentWillReceiveProps (nextProps) {
+    if (nextProps.value !== this.aceEditor.getValue()) {
+      this.aceEditor.setValue(nextProps.value, -1)
+    }
+
+    if (nextProps.indentation != undefined) {
+      this.aceEditor.getSession().setTabSize(this.props.indentation)
+    }
+
+    // TODO: only resize only when needed
+    setTimeout(() => {
+      this.aceEditor.resize(false);
+    }, 0)
+  }
+
+  componentWillUnmount () {
+    // neatly destroy ace editor, it has created a worker for validation
+    this.aceEditor.destroy()
+  }
+
+  handleChange = () => {
+    if (this.props && this.props.onChange) {
+      // TODO: pass a diff
+      this.props.onChange(this.aceEditor.getValue())
+    }
+  }
+}
\ No newline at end of file
diff --git a/src/components/CodeMode.js b/src/components/CodeMode.js
index ef068d2..7092150 100644
--- a/src/components/CodeMode.js
+++ b/src/components/CodeMode.js
@@ -1,6 +1,6 @@
 import { h } from 'preact'
 import TextMode from './TextMode'
-import ace from '../assets/ace'
+import Ace from './Ace'
 
 /**
  * CodeMode (powered by Ace editor)
@@ -11,7 +11,8 @@ import ace from '../assets/ace'
  *         options={Object}
  *         onChange={function(text: string)}
  *         onChangeMode={function(mode: string)}
- *         onLoadAce={function(aceEditor: Object, container: Element, options: Object) : Object}
+ *         onError={function(error: Error)}
+ *         onLoadAce={function(aceEditor: Object, container: Element) : Object}
  *     />
  *
  * Methods:
@@ -30,81 +31,30 @@ export default class CodeMode extends TextMode {
   constructor (props) {
     super(props)
 
-    this.state = {}
-
-    this.id = 'id' + Math.round(Math.random() * 1e6) // unique enough id within the JSONEditor
-    this.aceEditor = null
+    this.state = {
+      text: '{}'
+    }
   }
 
   render (props, state) {
     return h('div', {class: 'jsoneditor jsoneditor-mode-code'}, [
       this.renderMenu(),
 
-      h('div', {class: 'jsoneditor-contents', id: this.id})
+      h('div', {class: 'jsoneditor-contents'}, h(Ace, {
+        value: this.state.text,
+        onChange: this.handleChange,
+        onLoadAce: this.props.options.onLoadAce,
+        indentation: this.props.options.indentation,
+        ace: this.props.options.ace
+      })),
+
+      this.renderSchemaErrors ()
     ])
   }
 
-  componentDidMount () {
-    const options = this.props.options || {}
+  handleChange = (text) => {
+    this.setState({ text })
 
-    const container = this.base.querySelector('#' + this.id)
-
-    // use ace from bundle, and if not available try to use from global
-    const _ace = ace || window['ace']
-
-    let aceEditor = null
-    if (_ace && _ace.edit) {
-      // create ace editor
-      aceEditor = _ace.edit(container)
-
-      // bundle and load jsoneditor theme for ace editor
-      require('../assets/ace/theme-jsoneditor')
-
-      // configure ace editor
-      aceEditor.$blockScrolling = Infinity
-      aceEditor.setTheme('ace/theme/jsoneditor')
-      aceEditor.setShowPrintMargin(false)
-      aceEditor.setFontSize(13)
-      aceEditor.getSession().setMode('ace/mode/json')
-      aceEditor.getSession().setTabSize(options.indentation || 2)
-      aceEditor.getSession().setUseSoftTabs(true)
-      aceEditor.getSession().setUseWrapMode(true)
-      aceEditor.commands.bindKey('Ctrl-L', null)    // disable Ctrl+L (is used by the browser to select the address bar)
-      aceEditor.commands.bindKey('Command-L', null) // disable Ctrl+L (is used by the browser to select the address bar)
-    }
-    else {
-      // ace is excluded from the bundle.
-    }
-
-    // allow changing the config or completely replacing aceEditor
-    this.aceEditor = options.onLoadAce
-        ? options.onLoadAce(aceEditor, container, options) || aceEditor
-        : aceEditor
-
-    // register onchange event
-    this.aceEditor.on('change', this.handleChange)
-
-    // set initial text
-    this.setText('{}')
-  }
-
-  componentWillUnmount () {
-    this.destroy()
-  }
-
-  /**
-   * Destroy the editor
-   */
-  destroy () {
-    // neatly destroy ace editor
-    this.aceEditor.destroy()
-  }
-
-  componentDidUpdate () {
-    // TODO: handle changes in props
-  }
-
-  handleChange = () => {
     if (this.props.options && this.props.options.onChangeText) {
       // TODO: pass a diff
       this.props.options.onChangeText()
@@ -116,7 +66,7 @@ export default class CodeMode extends TextMode {
    * @param {string} text
    */
   setText (text) {
-    this.aceEditor.setValue(text, -1)
+    this.setState({text})
   }
 
   /**
@@ -124,6 +74,6 @@ export default class CodeMode extends TextMode {
    * @return {string} text
    */
   getText () {
-    return this.aceEditor.getValue()
+    return this.state.text
   }
 }
\ No newline at end of file
diff --git a/src/components/TextMode.js b/src/components/TextMode.js
index 40a6608..fdd31c1 100644
--- a/src/components/TextMode.js
+++ b/src/components/TextMode.js
@@ -1,6 +1,8 @@
 import { h, Component } from 'preact'
+import Ajv from 'ajv'
 import { parseJSON } from '../utils/jsonUtils'
 import { escapeUnicodeChars } from '../utils/stringUtils'
+import { enrichSchemaError, limitErrors } from '../utils/schemaUtils'
 import { jsonToData, dataToJson, patchData } from '../jsonData'
 import ModeButton from './menu/ModeButton'
 
@@ -13,6 +15,7 @@ import ModeButton from './menu/ModeButton'
  *         options={Object}
  *         onChange={function(text: string)}
  *         onChangeMode={function(mode: string)}
+ *         onError={function(error: Error)}
  *     />
  *
  * Methods:
@@ -33,7 +36,8 @@ export default class TextMode extends Component {
     super(props)
 
     this.state = {
-      text: '{}'
+      text: '{}',
+      compiledSchema: null
     }
   }
 
@@ -47,7 +51,9 @@ export default class TextMode extends Component {
           value: this.state.text,
           onInput: this.handleChange
         })
-      ])
+      ]),
+
+      this.renderSchemaErrors ()
     ])
   }
 
@@ -73,11 +79,86 @@ export default class TextMode extends Component {
         modes: this.props.options.modes,
         mode: this.props.mode,
         onChangeMode: this.props.onChangeMode,
-        onError: this.handleError
+        onError: this.props.onError
       })
     ])
   }
 
+  /** @protected */
+  renderSchemaErrors () {
+    // TODO: move the JSON Schema stuff into a separate Component?
+    if (!this.state.compiledSchema) {
+      return null
+    }
+
+    try {
+      // TODO: only validate again when json is changed since last validation
+      const json = this.get(); // this can fail when there is no valid json
+      const valid = this.state.compiledSchema(json)
+      if (!valid) {
+        const allErrors = this.state.compiledSchema.errors.map(enrichSchemaError)
+        const limitedErrors = limitErrors(allErrors)
+
+        return h('table', {class: 'jsoneditor-text-errors'},
+          h('tbody', {}, limitedErrors.map(TextMode.renderSchemaError))
+        )
+      }
+    }
+    catch (err) {
+      // no valid JSON, don't validate
+      return null
+    }
+  }
+
+  /**
+   * Render a table row of a single JSON schema error
+   * @param {Error | string} error
+   * @return {JSX.Element}
+   */
+  static renderSchemaError (error) {
+    const icon = h('input', {type: 'button', class: 'jsoneditor-schema-error'})
+
+    if (typeof error === 'string') {
+      return h('tr', {},
+        h('td', {}, icon),
+        h('td', {colSpan: 2}, h('pre', {}, error))
+      )
+    }
+    else {
+      return h('tr', {}, [
+        h('td', {}, icon),
+        h('td', {}, error.dataPath),
+        h('td', {}, error.message)
+      ])
+    }
+  }
+
+  /**
+   * Set a JSON schema for validation of the JSON object.
+   * To remove the schema, call JSONEditor.setSchema(null)
+   * @param {Object | null} schema
+   */
+  setSchema (schema) {
+    if (schema) {
+      const ajv = this.props.options.ajv ||
+          Ajv && Ajv({ allErrors: true, verbose: true })
+
+      if (!ajv) {
+        throw new Error('Cannot validate JSON: ajv not available. ' +
+            'Provide ajv via options or use a JSONEditor bundle including ajv.')
+      }
+
+      this.setState({
+        compiledSchema: ajv.compile(schema)
+      })
+    }
+    else {
+      this.setState({
+        compiledSchema: null
+      })
+    }
+  }
+
   /**
    * Get the configured indentation
    * @return {number}
@@ -106,7 +187,7 @@ export default class TextMode extends Component {
       this.format()
     }
     catch (err) {
-      this.handleError(err)
+      this.props.onError(err)
     }
   }
 
@@ -116,17 +197,7 @@ export default class TextMode extends Component {
       this.compact()
     }
     catch (err) {
-      this.handleError(err)
-    }
-  }
-
-  /** @protected */
-  handleError = (err) => {
-    if (this.props.options && this.props.options.onError) {
-      this.props.options.onError(err)
-    }
-    else {
-      console.error(err)
+      this.props.onError(err)
     }
   }
 
@@ -205,11 +276,4 @@ export default class TextMode extends Component {
   getText () {
     return this.state.text
   }
-
-  /**
-   * Destroy the editor
-   */
-  destroy () {
-
-  }
 }
\ No newline at end of file
diff --git a/src/components/TreeMode.js b/src/components/TreeMode.js
index 1b6da9a..6967c72 100644
--- a/src/components/TreeMode.js
+++ b/src/components/TreeMode.js
@@ -112,7 +112,7 @@ export default class TreeMode extends Component {
           modes: this.props.options.modes,
           mode: this.props.mode,
           onChangeMode: this.props.onChangeMode,
-          onError: this.handleError
+          onError: this.props.onError
         })
       ])
     }
@@ -213,16 +213,6 @@ export default class TreeMode extends Component {
     this.emitOnChange (actions, result.revert)
   }
 
-  /** @private */
-  handleError = (err) => {
-    if (this.props.options && this.props.options.onError) {
-      this.props.options.onError(err)
-    }
-    else {
-      console.error(err)
-    }
-  }
-
   /**
    * Emit an onChange event when there is a listener for it.
    * @param {JSONPatch} patch
@@ -372,6 +362,16 @@ export default class TreeMode extends Component {
     return JSON.stringify(this.get(), null, indentation)
   }
 
+  /**
+   * Set a JSON schema for validation of the JSON object.
+   * To remove the schema, call JSONEditor.setSchema(null)
+   * @param {Object | null} schema
+   */
+  setSchema (schema) {
+    // TODO: implement setSchema for TreeMode
+    console.error('setSchema not yet implemented for TreeMode')
+  }
+
   /**
    * Expand one or multiple objects or arrays
    * @param {Path | function (path: Path) : boolean} callback
@@ -422,13 +422,6 @@ export default class TreeMode extends Component {
         : TreeMode.expandAll(path)
   }
 
-  /**
-   * Destroy the editor
-   */
-  destroy () {
-
-  }
-
   /**
    * Default function to determine whether or not to expand a node initially
    *
diff --git a/src/develop.html b/src/develop.html
index 480b631..07e9560 100644
--- a/src/develop.html
+++ b/src/develop.html
@@ -13,7 +13,7 @@
 
   <style>
     #container {
-      height: 500px;
+      height: 400px;
       width: 100%;
       max-width : 800px;
     }
@@ -24,11 +24,13 @@
   <button id="setJSON">Set JSON</button>
   <button id="getJSON">Get JSON</button>
 
+  <button id="toggleSchema">Toggle JSON Schema</button>
+
   <label for="mode">mode:
     <select id="mode">
       <option value="text">text</option>
-      <option value="code">code</option>
-      <option value="tree" selected>tree</option>
+      <option value="code" selected>code</option>
+      <option value="tree">tree</option>
       <option value="form">form</option>
       <option value="view">view</option>
     </select>
@@ -83,6 +85,28 @@
     }
   })
 
+  const schema = {
+    "title": "Example Schema",
+    "type": "object",
+    "properties": {
+      "firstName": {
+        "type": "string"
+      },
+      "lastName": {
+        "type": "string"
+      },
+      "gender": {
+        "enum": ["male", "female"]
+      },
+      "age": {
+        "description": "Age in years",
+        "type": "integer",
+        "minimum": 0
+      }
+    },
+    "required": ["firstName", "lastName"]
+  }
+
   // set json
   document.getElementById('setJSON').onclick = function () {
     editor.set(largeJson, {
@@ -92,6 +116,13 @@
     })
   }
 
+  // set schema
+  let hasSchema = false
+  document.getElementById('toggleSchema').onclick = function () {
+    editor.setSchema(hasSchema ? null : schema)
+    hasSchema = !hasSchema
+  }
+
   // get json
   document.getElementById('getJSON').onclick = function () {
     const json = editor.get()
diff --git a/src/index.js b/src/index.js
index 630da89..fe7e9f4 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,4 +1,4 @@
-import { h, render } from 'preact'
+import { h, render,  } from 'preact'
 import CodeMode from './components/CodeMode'
 import TextMode from './components/TextMode'
 import TreeMode from './components/TreeMode'
@@ -30,13 +30,9 @@ function jsoneditor (container, options = {}) {
   const editor = {
     isJSONEditor: true,
 
-    utils: {
-      compileJSONPointer,
-      parseJSONPointer
-    },
-
     _container: container,
     _options: options,
+    _schema: null,
     _modes: modes,
     _mode: null,
     _element: null,
@@ -76,6 +72,16 @@ function jsoneditor (container, options = {}) {
     return editor._component.getText()
   }
 
+  /**
+   * Set a JSON schema for validation of the JSON object.
+   * To remove the schema, call JSONEditor.setSchema(null)
+   * @param {Object | null} schema
+   */
+  editor.setSchema = function (schema) {
+    editor._schema = schema || null
+    editor._component.setSchema(schema)
+  }
+
   /**
    * Expand one or multiple objects or arrays.
    *
@@ -154,15 +160,33 @@ function jsoneditor (container, options = {}) {
         }
       }
 
+      function handleError (err) {
+        if (editor._options && editor._options.onError) {
+          editor._options.onError(err)
+        }
+        else {
+          console.error(err)
+        }
+      }
+
       // create new component
       element = render(
           h(constructor, {
             mode,
             options: editor._options,
-            onChangeMode: handleChangeMode
+            onChangeMode: handleChangeMode,
+            onError: handleError
           }),
           editor._container)
 
+      // apply JSON schema (if any)
+      try {
+        element._component.setSchema(editor._schema)
+      }
+      catch (err) {
+        handleError(err)
+      }
+
       // set JSON (this can throw an error)
       const text = editor._component ? editor._component.getText() : '{}'
       element._component.setText(text)
@@ -174,8 +198,7 @@ function jsoneditor (container, options = {}) {
       if (success) {
         // destroy previous component
         if (editor._element) {
-          editor._element._component.destroy()
-          editor._element.parentNode.removeChild(editor._element)
+          unrender(container, editor._element)
         }
 
         editor._mode = mode
@@ -185,7 +208,8 @@ function jsoneditor (container, options = {}) {
       else {
         // TODO: fall back to text mode when loading code mode failed?
 
-        // remove the just created component if any (where construction or setText failed)
+        // remove the just created component if an error occurred during construction
+        // (for example when construction or setText failed)
         const childCount = editor._container.children.length
         if (childCount !== initialChildCount) {
           editor._container.removeChild(editor._container.lastChild)
@@ -194,11 +218,31 @@ function jsoneditor (container, options = {}) {
     }
   }
 
-  // TODO: implement destroy
+  /**
+   * Remove the editor from the DOM and clean up workers
+   */
+  editor.destroy = function () {
+    unrender(container, editor._element)
+  }
 
   editor.setMode(options && options.mode || 'tree')
 
   return editor
 }
 
+// expose util functions
+jsoneditor.utils = {
+  compileJSONPointer,
+  parseJSONPointer
+}
+
+/**
+ * Destroy a rendered preact component
+ * @param container
+ * @param root
+ */
+function unrender (container, root) {
+  render('', container, root);
+}
+
 module.exports = jsoneditor
diff --git a/src/jsoneditor.less b/src/jsoneditor.less
index 25fc2c1..a9e3044 100644
--- a/src/jsoneditor.less
+++ b/src/jsoneditor.less
@@ -567,3 +567,37 @@ textarea.jsoneditor-text {
   font-size: @fontSize;
   color: @black;
 }
+
+div.jsoneditor-code {
+  width: 100%;
+  height: 100%;
+  min-height: @contentsMinHeight;
+}
+
+/* JSON schema errors displayed at the bottom of the editor in mode text and code */
+
+.jsoneditor-text-errors {
+  width: 100%;
+  border-collapse: collapse;
+  background-color: #ffef8b;
+  border-top: 1px solid #ffd700;
+
+  font-family: @fontFamily;
+  font-size: @fontSize;
+
+  td {
+    padding: 3px 6px;
+    vertical-align: middle;
+  }
+
+  .jsoneditor-schema-error {
+    user-select: none;
+    outline: none;
+    border: none;
+    width: 24px;
+    height: 24px;
+    padding: 0;
+    margin: 0 4px 0 0;
+    background: url('img/jsoneditor-icons.svg')  -168px -46px;
+  }
+}
diff --git a/src/typedef.js b/src/typedef.js
index 8c06846..b280657 100644
--- a/src/typedef.js
+++ b/src/typedef.js
@@ -32,17 +32,19 @@
  *
  * @typedef {{
  *   name: string?,
- *   mode?: 'code' | 'form' | 'text' | 'tree' | 'view',
- *   modes?: string[],
- *   history?: boolean,
- *   indentation?: number | string,
- *   onChange?: function (patch: JSONPatch, revert: JSONPatch),
- *   onChangeText?: function (),
- *   onChangeMode?: function (mode: string, prevMode: string),
- *   onError?:  function (err: Error),
- *   isPropertyEditable?: function (Path) : boolean
- *   isValueEditable?: function (Path) : boolean,
- *   escapeUnicode:? boolean
+ *   mode: 'code' | 'form' | 'text' | 'tree' | 'view'?,
+ *   modes: string[]?,
+ *   history: boolean?,
+ *   indentation: number | string?,
+ *   onChange: function (patch: JSONPatch, revert: JSONPatch)?,
+ *   onChangeText: function ()?,
+ *   onChangeMode: function (mode: string, prevMode: string)?,
+ *   onError:  function (err: Error)?,
+ *   isPropertyEditable: function (Path)?
+ *   isValueEditable: function (Path)?,
+ *   escapeUnicode: boolean?,
+ *   ajv: Object?
+ *   ace: Object?
  * }} Options
  *
  * @typedef {{
diff --git a/src/utils/schemaUtils.js b/src/utils/schemaUtils.js
new file mode 100644
index 0000000..4578a3e
--- /dev/null
+++ b/src/utils/schemaUtils.js
@@ -0,0 +1,49 @@
+
+// TODO: make MAX_ERRORS configurable
+export const MAX_ERRORS = 3; // maximum number of displayed errors at the bottom
+
+/**
+ * Enrich the error message of a JSON schema error
+ * @param {Object} error
+ * @return {Object} The improved error
+ */
+export function enrichSchemaError(error) {
+  if (error.keyword === 'enum' && Array.isArray(error.schema)) {
+    let enums = error.schema
+    if (enums) {
+      enums = enums.map(JSON.stringify)
+
+      if (enums.length > 5) {
+        const more = ['(' + (enums.length - 5) + ' more...)']
+        enums = enums.slice(0, 5)
+        enums.push(more)
+      }
+      error.message = 'should be equal to one of: ' + enums.join(', ')
+    }
+  }
+
+  if (error.keyword === 'additionalProperties') {
+    error.message = 'should NOT have additional property: ' + error.params.additionalProperty
+  }
+
+  return error
+}
+
+
+/**
+ * Limit the number of errors.
+ * If the number of errors exceeds the maximum, the tail is removed and
+ * a message that there are more errors is added
+ * @param {Array} errors
+ * @return {Array} Returns limited items
+ */
+export function limitErrors (errors) {
+  if (errors.length > MAX_ERRORS) {
+    const hidden = errors.length - MAX_ERRORS
+    let limitedErrors = errors.slice(0, MAX_ERRORS)
+    limitedErrors.push('(' + hidden + ' more errors...)')
+    return limitedErrors
+  }
+
+  return errors
+}
\ No newline at end of file