diff --git a/app/package.json b/app/package.json
index 3aeffcd..33b6bc7 100644
--- a/app/package.json
+++ b/app/package.json
@@ -12,6 +12,7 @@
     "@material-ui/core": "^4.0.0-alpha.0",
     "@material-ui/icons": "^3.0.1",
     "@material-ui/styles": "^3.0.0-alpha.8",
+    "@types/diff": "^4.0.1",
     "@types/node": "^10.12.18",
     "@types/react": "^16.7.18",
     "@types/react-dom": "^16.0.11",
@@ -26,18 +27,21 @@
     "compare-versions": "^3.4.0",
     "copy-text-to-clipboard": "^1.0.4",
     "css-loader": "^2.1.0",
+    "diff": "^4.0.1",
     "electron-nucleus": "^1.11.0",
     "electron-telemetry": "git+https://github.com/thomasnordquist/electron-telemetry.git#dist",
     "html-webpack-plugin": "^4.0.0-beta.5",
     "jquery": "^3.3.1",
     "lodash.debounce": "^4.0.8",
     "lodash.throttle": "^4.1.1",
+    "monaco-editor-webpack-plugin": "^1.7.0",
     "moving-average": "^1.0.0",
     "number-abbreviate": "^2.0.0",
     "react": "16.8",
     "react-ace": "^6.3.2",
     "react-dom": "^16.7.0",
     "react-json-view": "^1.19.1",
+    "react-monaco-editor": "^0.24.0",
     "react-redux": "^6.0.0",
     "react-resize-detector": "^3.4.0",
     "react-split-pane": "^0.1.85",
diff --git a/app/src/components/Sidebar/Sidebar.tsx b/app/src/components/Sidebar/Sidebar.tsx
index 3797953..c9ca855 100644
--- a/app/src/components/Sidebar/Sidebar.tsx
+++ b/app/src/components/Sidebar/Sidebar.tsx
@@ -166,7 +166,7 @@ class Sidebar extends React.Component<Props, State> {
             <div ref={this.valueRef}>
             <React.Suspense fallback={<div>Loading...</div>}>
               <ReactResizeDetector handleWidth={true} onResize={this.valueRenderWidthChange} />
-              <ValueRenderer message={this.props.node && this.props.node.message} />
+              <ValueRenderer node={this.props.node} />
             </React.Suspense>
             </div>
             <div><MessageHistory onSelect={this.handleMessageHistorySelect} node={this.props.node} /></div>
diff --git a/app/src/components/Sidebar/ValueRenderer.tsx b/app/src/components/Sidebar/ValueRenderer.tsx
index 6a88fd7..ee5046d 100644
--- a/app/src/components/Sidebar/ValueRenderer.tsx
+++ b/app/src/components/Sidebar/ValueRenderer.tsx
@@ -1,26 +1,42 @@
-import * as React from 'react'
 import * as q from '../../../../backend/src/Model'
-
+import * as React from 'react'
+import MonacoEditor, { MonacoDiffEditor, MonacoEditorBaseProps, MonacoEditorProps } from 'react-monaco-editor'
+import ReactResizeDetector from 'react-resize-detector'
 import { Theme, withTheme } from '@material-ui/core/styles'
-
-import { default as ReactJson } from 'react-json-view'
+import * as diff from 'diff'
 
 interface Props {
-  message?: q.Message
+  node?: q.TreeNode<any>,
   theme: Theme
 }
 
-class ValueRenderer extends React.Component<Props, {}> {
+interface State {
+  width: number
+  modifiedValue?: string
+  node?: q.TreeNode<any>
+  currentMessage?: q.Message
+}
+
+class ValueRenderer extends React.Component<Props, State> {
+  constructor(props: Props) {
+    super(props)
+    this.state = { width: 0, node: props.node }
+  }
+
   public render() {
     return <div style={{ padding: '8px 0px 8px 8px' }}>{this.renderValue()}</div>
   }
 
   public renderValue() {
-    const { message } = this.props
-    if (!message) {
+    const { node } = this.props
+    if (!node || !node.message) {
       return null
     }
 
+    const message = node.message
+    const previousMessages = node.messageHistory.toArray()
+    const previousMessage = previousMessages[previousMessages.length - 2]
+    debugger
     let json
     try {
       json = JSON.parse(message.value)
@@ -36,17 +52,96 @@ class ValueRenderer extends React.Component<Props, {}> {
       return this.renderRawValue(message.value)
     } else {
       const theme = (this.props.theme.palette.type === 'dark') ? 'monokai' : 'bright:inverted'
+      const current = this.messageToPrettyJson(message)
+      const previous = this.messageToPrettyJson(previousMessage)
+
       return (
-        <ReactJson
-          style={{ width: '100%', overflowY: 'scroll', wordBreak: 'break-all' }}
-          src={json}
-          name={null}
-          theme={theme}
-        />
+        <div>
+          <ReactResizeDetector handleWidth={true} onResize={this.updateWidth} />
+          {this.renderDiff(current, previous || current)}
+        </div>
       )
     }
   }
 
+  public static getDerivedStateFromProps(props: Props, state: State) {
+    const discardEdit = props.node !== state.node || (props.node && props.node.message !== state.currentMessage)
+    return {
+      ...state,
+      node: props.node,
+      currentMessage: props.node && props.node.message,
+      modifiedValue: discardEdit ? undefined : state.modifiedValue,
+    }
+  }
+
+  private heightForLines(lines: number) {
+    return 0 + (lines * 18)
+  }
+
+  private editorOptions = {
+    lineHeigh: 16,
+    lineNumbers: 'off' as 'off',
+    scrollBeyondLastLine: false,
+    minimap: { enabled: false },
+    theme: 'vs-dark',
+  }
+
+  private renderDiff(current: string = '', previous: string = '') {
+    const value = this.state.modifiedValue !== undefined ? this.state.modifiedValue : current
+    const lines = this.expectedLineCountFor(value, previous)
+    const height = this.heightForLines(lines)
+    return (
+      <MonacoDiffEditor
+        language="json"
+        height={Math.min(height, 200)}
+        options={{ ...this.editorOptions, renderSideBySide: false }}
+        onChange={value => this.setState({ modifiedValue: value })}
+        original={previous}
+        width={this.state.width}
+        value={value}
+      />
+    )
+  }
+
+  private expectedLineCountFor(current?: string, original?: string): number {
+    if (current === undefined) {
+      return 0
+    }
+
+    const originalStr = original || ''
+    const changes = diff.diffLines(originalStr, current)
+
+    const added = changes
+      .map((change) => {
+        const added = (change.added && change.count) || 0
+        const removed = (change.removed && change.count) || 0
+
+        return Math.abs(added)
+      })
+      .reduce((a, b) => a + b, 0)
+
+    const originalLines = originalStr.split('\n').length
+
+    return originalLines + added
+  }
+
+  private messageToPrettyJson(message?: q.Message): string | undefined {
+    if (!message || !message.value) {
+      return undefined
+    }
+
+    try {
+      const json = JSON.parse(message.value)
+      return JSON.stringify(json, undefined, '  ')
+    } catch {
+      return undefined
+    }
+  }
+
+  private updateWidth = (width: number) => {
+    this.setState({ width })
+  }
+
   private renderRawValue(value: string) {
     const style: React.CSSProperties = {
       padding: '8px 12px 8px 12px',
diff --git a/app/webpack.config.js b/app/webpack.config.js
index afe1d6e..5b0ceb5 100644
--- a/app/webpack.config.js
+++ b/app/webpack.config.js
@@ -1,6 +1,7 @@
 const LiveReloadPlugin = require('webpack-livereload-plugin');
 const BundleAnalyzerPlugin = require('webpack-bundle-analyzer').BundleAnalyzerPlugin;
 const HtmlWebpackPlugin = require('html-webpack-plugin')
+const MonacoWebpackPlugin = require('monaco-editor-webpack-plugin')
 
 module.exports = {
     entry: {
@@ -66,6 +67,10 @@ module.exports = {
     plugins: [
       new LiveReloadPlugin({}),
       new HtmlWebpackPlugin({ template: './index.html', file: './build/index.html', inject: false }),
+      new MonacoWebpackPlugin({
+        // available options are documented at https://github.com/Microsoft/monaco-editor-webpack-plugin#options
+        languages: ['json']
+      })
     //   new BundleAnalyzerPlugin(),
     ],
 
diff --git a/app/yarn.lock b/app/yarn.lock
index ea24a58..4d3b248 100644
--- a/app/yarn.lock
+++ b/app/yarn.lock
@@ -111,6 +111,16 @@
     prop-types "^15.6.0"
     react-is "^16.8.0"
 
+"@types/anymatch@*":
+  version "1.3.1"
+  resolved "https://registry.yarnpkg.com/@types/anymatch/-/anymatch-1.3.1.tgz#336badc1beecb9dacc38bea2cf32adf627a8421a"
+  integrity sha512-/+CRPXpBDpo2RK9C68N3b2cOvO0Cf5B9aPijHsoDQTHivnGSObdOF2BRQOYjojWTDy6nQvMjmqRXIxH55VjxxA==
+
+"@types/diff@^4.0.1":
+  version "4.0.1"
+  resolved "https://registry.yarnpkg.com/@types/diff/-/diff-4.0.1.tgz#471950ff97e2205ab02404bd7ac960fac074d886"
+  integrity sha512-BFob98KGKIqjcJjbmO/g+daJinDOtSUs27e0NTirODSUHYhUUAVXmq/nKIrmRFsOHrOWj5mncvByrzyw1X1PNQ==
+
 "@types/jss@^9.5.6":
   version "9.5.7"
   resolved "https://registry.yarnpkg.com/@types/jss/-/jss-9.5.7.tgz#fa57a6d0b38a3abef8a425e3eb6a53495cb9d5a0"
@@ -185,6 +195,18 @@
   resolved "https://registry.yarnpkg.com/@types/socket.io-client/-/socket.io-client-1.4.32.tgz#988a65a0386c274b1c22a55377fab6a30789ac14"
   integrity sha512-Vs55Kq8F+OWvy1RLA31rT+cAyemzgm0EWNeax6BWF8H7QiiOYMJIdcwSDdm5LVgfEkoepsWkS+40+WNb7BUMbg==
 
+"@types/tapable@*":
+  version "1.0.4"
+  resolved "https://registry.yarnpkg.com/@types/tapable/-/tapable-1.0.4.tgz#b4ffc7dc97b498c969b360a41eee247f82616370"
+  integrity sha512-78AdXtlhpCHT0K3EytMpn4JNxaf5tbqbLcbIRoQIHzpTIyjpxLQKRoxU55ujBXAtg3Nl2h/XWvfDa9dsMOd0pQ==
+
+"@types/uglify-js@*":
+  version "3.0.4"
+  resolved "https://registry.yarnpkg.com/@types/uglify-js/-/uglify-js-3.0.4.tgz#96beae23df6f561862a830b4288a49e86baac082"
+  integrity sha512-SudIN9TRJ+v8g5pTG8RRCqfqTMNqgWCKKd3vtynhGzkIIjxaicNAMuY5TRadJ6tzDu3Dotf3ngaMILtmOdmWEQ==
+  dependencies:
+    source-map "^0.6.1"
+
 "@types/uuid@^3.4.4":
   version "3.4.4"
   resolved "https://registry.yarnpkg.com/@types/uuid/-/uuid-3.4.4.tgz#7af69360fa65ef0decb41fd150bf4ca5c0cefdf5"
@@ -199,6 +221,17 @@
   dependencies:
     moment ">=2.13.0"
 
+"@types/webpack@^4.4.19":
+  version "4.4.24"
+  resolved "https://registry.yarnpkg.com/@types/webpack/-/webpack-4.4.24.tgz#75bc301176066f566ec54151b6101c2b45abb8b2"
+  integrity sha512-yg99CjvB7xZ/iuHrsZ7dkGKoq/FRDzqLzAxKh2EmTem6FWjzrty4FqCqBYuX5z+MFwSaaQGDAX4Q9HQkLjGLnQ==
+  dependencies:
+    "@types/anymatch" "*"
+    "@types/node" "*"
+    "@types/tapable" "*"
+    "@types/uglify-js" "*"
+    source-map "^0.6.0"
+
 "@webassemblyjs/ast@1.7.11":
   version "1.7.11"
   resolved "https://registry.yarnpkg.com/@webassemblyjs/ast/-/ast-1.7.11.tgz#b988582cafbb2b095e8b556526f30c90d057cace"
@@ -1645,6 +1678,11 @@ diff-match-patch@^1.0.4:
   resolved "https://registry.yarnpkg.com/diff-match-patch/-/diff-match-patch-1.0.4.tgz#6ac4b55237463761c4daf0dc603eb869124744b1"
   integrity sha512-Uv3SW8bmH9nAtHKaKSanOQmj2DnlH65fUpcrMdfdaOxUG02QQ4YGZ8AE7kKOMisF7UqvOlGKVYWRvezdncW9lg==
 
+diff@^4.0.1:
+  version "4.0.1"
+  resolved "https://registry.yarnpkg.com/diff/-/diff-4.0.1.tgz#0c667cb467ebbb5cea7f14f135cc2dba7780a8ff"
+  integrity sha512-s2+XdvhPCOF01LRQBC8hf4vhbVmI2CGS5aZnxLJlT5FtdhPCDFq80q++zK2KlrVorVDdL5BOGZ/VfLrVtYNF+Q==
+
 diffie-hellman@^5.0.0:
   version "5.0.3"
   resolved "https://registry.yarnpkg.com/diffie-hellman/-/diffie-hellman-5.0.3.tgz#40e8ee98f55a2149607146921c63e1ae5f3d2875"
@@ -3621,6 +3659,18 @@ moment@>=2.13.0:
   resolved "https://registry.yarnpkg.com/moment/-/moment-2.24.0.tgz#0d055d53f5052aa653c9f6eb68bb5d12bf5c2b5b"
   integrity sha512-bV7f+6l2QigeBBZSM/6yTNq4P2fNpSWj/0e7jQcy87A8e7o2nAfP/34/2ky5Vw4B9S446EtIhodAzkFCcR4dQg==
 
+monaco-editor-webpack-plugin@^1.7.0:
+  version "1.7.0"
+  resolved "https://registry.yarnpkg.com/monaco-editor-webpack-plugin/-/monaco-editor-webpack-plugin-1.7.0.tgz#920cbeecca25f15d70d568a7e11b0ba4daf1ae83"
+  integrity sha512-oItymcnlL14Sjd7EF7q+CMhucfwR/2BxsqrXIBrWL6LQplFfAfV+grLEQRmVHeGSBZ/Gk9ptzfueXnWcoEcFuA==
+  dependencies:
+    "@types/webpack" "^4.4.19"
+
+monaco-editor@^0.15.6:
+  version "0.15.6"
+  resolved "https://registry.yarnpkg.com/monaco-editor/-/monaco-editor-0.15.6.tgz#d63b3b06f86f803464f003b252627c3eb4a09483"
+  integrity sha512-JoU9V9k6KqT9R9Tiw1RTU8ohZ+Xnf9DMg6Ktqqw5hILumwmq7xqa/KLXw513uTUsWbhtnHoSJYYR++u3pkyxJg==
+
 move-concurrently@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/move-concurrently/-/move-concurrently-1.0.1.tgz#be2c005fda32e0b29af1f05d7c4b33214c701f92"
@@ -4525,6 +4575,15 @@ react-lifecycles-compat@^3.0.2, react-lifecycles-compat@^3.0.4:
   resolved "https://registry.yarnpkg.com/react-lifecycles-compat/-/react-lifecycles-compat-3.0.4.tgz#4f1a273afdfc8f3488a8c516bfda78f872352362"
   integrity sha512-fBASbA6LnOU9dOU2eW7aQ8xmYBSXUIWr+UmF9b1efZBazGNO+rcXT/icdKnYm2pTwcRylVUYwW7H1PHfLekVzA==
 
+react-monaco-editor@^0.24.0:
+  version "0.24.0"
+  resolved "https://registry.yarnpkg.com/react-monaco-editor/-/react-monaco-editor-0.24.0.tgz#30e2028d3e235edc16a0e488f241637677929d54"
+  integrity sha512-SOCxZQYPVKShzVWPOMG0i+TM6l+I862x/+IpV+QPjTEtfh12Q+Cl6NO14EPnlphd9e8lmyFAKr5Md0aRdQfcLg==
+  dependencies:
+    "@types/react" "*"
+    monaco-editor "^0.15.6"
+    prop-types "^15.6.2"
+
 react-motion@^0.5.2:
   version "0.5.2"
   resolved "https://registry.yarnpkg.com/react-motion/-/react-motion-0.5.2.tgz#0dd3a69e411316567927917c6626551ba0607316"