diff --git a/.eslintrc b/.eslintrc
index 04a5a3af..47dc0576 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -9,9 +9,10 @@
     "react/jsx-uses-react": 2,
     "react/jsx-uses-vars": 2,
     "react/react-in-jsx-scope": 2,
+    "no-console": 0,
     // Temporarily disabled due to babel-eslint issues:
     "block-scoped-var": 0,
-    "padded-blocks": 0
+    "padded-blocks": 0,
   },
   "plugins": [
     "react"
diff --git a/src/createDevTools.js b/src/createDevTools.js
new file mode 100644
index 00000000..127f235c
--- /dev/null
+++ b/src/createDevTools.js
@@ -0,0 +1,55 @@
+import createAll from 'react-redux/lib/components/createAll';
+import { bindActionCreators } from 'redux';
+import { ActionCreators } from './devTools';
+
+export default function createDevTools(React) {
+  const { PropTypes, Component } = React;
+  const { Provider, Connector } = createAll(React);
+
+  return class DevTools extends Component {
+    static propTypes = {
+      monitor: PropTypes.func.isRequired,
+      store: PropTypes.shape({
+        devToolsStore: PropTypes.shape({
+          dispatch: PropTypes.func.isRequired
+        }).isRequired
+      }).isRequired
+    };
+
+    constructor(props, context) {
+      if (props.store && !props.store.devToolsStore) {
+        console.error(
+          'Could not find the devTools store inside your store. ' +
+          'Have you applied devTools() higher-order store?'
+        );
+      }
+      super(props, context);
+    }
+
+    render() {
+      const { devToolsStore } = this.props.store;
+      return (
+        <Provider store={devToolsStore}>
+          {this.renderRoot}
+        </Provider>
+      );
+    }
+
+    renderRoot = () => {
+      return (
+        <Connector>
+          {this.renderMonitor}
+        </Connector>
+      );
+    };
+
+    renderMonitor = ({ dispatch, ...state }) => {
+      const { monitor: Monitor, ...rest } = this.props;
+      return (
+        <Monitor {...state}
+                 {...bindActionCreators(ActionCreators, dispatch)}
+                 {...rest} />
+      );
+    };
+  };
+}
diff --git a/src/devTools.js b/src/devTools.js
new file mode 100644
index 00000000..10677a4d
--- /dev/null
+++ b/src/devTools.js
@@ -0,0 +1,213 @@
+const ActionTypes = {
+  PERFORM_ACTION: 'PERFORM_ACTION',
+  RESET: 'RESET',
+  ROLLBACK: 'ROLLBACK',
+  COMMIT: 'COMMIT',
+  SWEEP: 'SWEEP',
+  TOGGLE_ACTION: 'TOGGLE_ACTION'
+};
+
+const INIT_ACTION = {
+  type: '@@INIT'
+};
+
+function last(arr) {
+  return arr[arr.length - 1];
+}
+
+function toggle(obj, key) {
+  const clone = { ...obj };
+  if (clone[key]) {
+    delete clone[key];
+  } else {
+    clone[key] = true;
+  }
+  return clone;
+}
+
+/**
+ * Computes the next entry in the log by applying an action.
+ */
+function computeNextEntry(reducer, action, state, error) {
+  if (error) {
+    return {
+      state,
+      error: 'Interrupted by an error up the chain'
+    };
+  }
+
+  let nextState = state;
+  let nextError;
+  try {
+    nextState = reducer(state, action);
+  } catch (err) {
+    nextError = err.toString();
+  }
+
+  return {
+    state: nextState,
+    error: nextError
+  };
+}
+
+/**
+ * Runs the reducer on all actions to get a fresh computation log.
+ * It's probably a good idea to do this only if the code has changed,
+ * but until we have some tests we'll just do it every time an action fires.
+ */
+function recomputeStates(reducer, committedState, stagedActions, skippedActions) {
+  const computedStates = [];
+
+  for (let i = 0; i < stagedActions.length; i++) {
+    const action = stagedActions[i];
+
+    const previousEntry = computedStates[i - 1];
+    const previousState = previousEntry ? previousEntry.state : committedState;
+    const previousError = previousEntry ? previousEntry.error : undefined;
+
+    const shouldSkip = Boolean(skippedActions[i]);
+    const entry = shouldSkip ?
+      previousEntry :
+      computeNextEntry(reducer, action, previousState, previousError);
+
+    computedStates.push(entry);
+  }
+
+  return computedStates;
+}
+
+
+/**
+ * Lifts the app state reducer into a DevTools state reducer.
+ */
+function liftReducer(reducer, initialState) {
+  const initialLiftedState = {
+    committedState: initialState,
+    stagedActions: [INIT_ACTION],
+    skippedActions: {}
+  };
+
+  /**
+   * Manages how the DevTools actions modify the DevTools state.
+   */
+  return function liftedReducer(liftedState = initialLiftedState, liftedAction) {
+    let {
+      committedState,
+      stagedActions,
+      skippedActions,
+      computedStates
+    } = liftedState;
+
+    switch (liftedAction.type) {
+    case ActionTypes.RESET:
+      committedState = initialState;
+      stagedActions = [INIT_ACTION];
+      skippedActions = {};
+      break;
+    case ActionTypes.COMMIT:
+      committedState = last(computedStates).state;
+      stagedActions = [INIT_ACTION];
+      skippedActions = {};
+      break;
+    case ActionTypes.ROLLBACK:
+      stagedActions = [INIT_ACTION];
+      skippedActions = {};
+      break;
+    case ActionTypes.TOGGLE_ACTION:
+      const { index } = liftedAction;
+      skippedActions = toggle(skippedActions, index);
+      break;
+    case ActionTypes.SWEEP:
+      stagedActions = stagedActions.filter((_, i) => !skippedActions[i]);
+      skippedActions = {};
+      break;
+    case ActionTypes.PERFORM_ACTION:
+      const { action } = liftedAction;
+      stagedActions = [...stagedActions, action];
+      break;
+    default:
+      break;
+    }
+
+    computedStates = recomputeStates(
+      reducer,
+      committedState,
+      stagedActions,
+      skippedActions
+    );
+
+    return {
+      committedState,
+      stagedActions,
+      skippedActions,
+      computedStates
+    };
+  };
+}
+
+/**
+ * Lifts an app action to a DevTools action.
+ */
+function liftAction(action) {
+  const liftedAction = { type: ActionTypes.PERFORM_ACTION, action };
+  return liftedAction;
+}
+
+/**
+ * Unlifts the DevTools state to the app state.
+ */
+function unliftState(liftedState) {
+  const { computedStates } = liftedState;
+  const { state } = last(computedStates);
+  return state;
+}
+
+/**
+ * Unlifts the DevTools store to act like the app's store.
+ */
+function unliftStore(liftedStore) {
+  return {
+    ...liftedStore,
+    devToolsStore: liftedStore,
+    dispatch(action) {
+      liftedStore.dispatch(liftAction(action));
+      return action;
+    },
+    getState() {
+      return unliftState(liftedStore.getState());
+    }
+  };
+}
+
+/**
+ * Action creators to change the DevTools state.
+ */
+export const ActionCreators = {
+  reset() {
+    return { type: ActionTypes.RESET };
+  },
+  rollback() {
+    return { type: ActionTypes.ROLLBACK };
+  },
+  commit() {
+    return { type: ActionTypes.COMMIT };
+  },
+  sweep() {
+    return { type: ActionTypes.SWEEP };
+  },
+  toggleAction(index) {
+    return { type: ActionTypes.TOGGLE_ACTION, index };
+  }
+};
+
+/**
+ * Redux DevTools middleware.
+ */
+export default function devTools() {
+  return next => (reducer, initialState) => {
+    const liftedReducer = liftReducer(reducer, initialState);
+    const liftedStore = next(liftedReducer);
+    const store = unliftStore(liftedStore);
+    return store;
+  };
+}
diff --git a/src/index.js b/src/index.js
index e69de29b..6e63a3a8 100644
--- a/src/index.js
+++ b/src/index.js
@@ -0,0 +1,2 @@
+export { default as devTools } from './devTools';
+export { default as persistState } from './persistState';
diff --git a/src/persistState.js b/src/persistState.js
new file mode 100644
index 00000000..09a6d598
--- /dev/null
+++ b/src/persistState.js
@@ -0,0 +1,39 @@
+export default function persistState(sessionId) {
+  if (!sessionId) {
+    return next => (...args) => next(...args);
+  }
+
+  return next => (reducer, initialState) => {
+    const key = `redux-dev-session-${sessionId}`;
+
+    let finalInitialState;
+    try {
+      finalInitialState = JSON.parse(localStorage.getItem(key)) || initialState;
+      next(reducer, initialState);
+    } catch (e) {
+      console.warn('Could not read debug session from localStorage:', e);
+      try {
+        localStorage.removeItem(key);
+      } finally {
+        finalInitialState = undefined;
+      }
+    }
+
+    const store = next(reducer, finalInitialState);
+
+    return {
+      ...store,
+      dispatch(action) {
+        store.dispatch(action);
+
+        try {
+          localStorage.setItem(key, JSON.stringify(store.getState()));
+        } catch (e) {
+          console.warn('Could not write debug session from localStorage:', e);
+        }
+
+        return action;
+      }
+    };
+  };
+}
diff --git a/src/react/DebugPanel.js b/src/react/DebugPanel.js
new file mode 100644
index 00000000..6dac89f4
--- /dev/null
+++ b/src/react/DebugPanel.js
@@ -0,0 +1,51 @@
+import React, { PropTypes } from 'react';
+
+export function getDefaultStyle(props) {
+  let { left, right, bottom, top } = props;
+  if (typeof left === 'undefined' && typeof right === 'undefined') {
+    right = true;
+  }
+  if (typeof top === 'undefined' && typeof bottom === 'undefined') {
+    bottom = true;
+  }
+
+  return {
+    position: 'fixed',
+    zIndex: 999,
+    fontSize: 17,
+    overflow: 'scroll',
+    opacity: 0.92,
+    background: 'black',
+    color: 'white',
+    padding: '1em',
+    left: left ? 0 : undefined,
+    right: right ? 0 : undefined,
+    top: top ? 0 : undefined,
+    bottom: bottom ? 0 : undefined,
+    maxHeight: (bottom && top) ? '100%' : '20%',
+    maxWidth: (left && right) ? '100%' : '20%',
+    wordWrap: 'break-word'
+  };
+}
+
+export default class DebugPanel {
+  static propTypes = {
+    left: PropTypes.bool,
+    right: PropTypes.bool,
+    bottom: PropTypes.bool,
+    top: PropTypes.bool,
+    getStyle: PropTypes.func.isRequired
+  };
+
+  static defaultProps = {
+    getStyle: getDefaultStyle
+  };
+
+  render() {
+    return (
+      <div style={this.props.getStyle(this.props)}>
+        {this.props.children}
+      </div>
+    );
+  }
+}
diff --git a/src/react/LogMonitor.js b/src/react/LogMonitor.js
new file mode 100644
index 00000000..4771178d
--- /dev/null
+++ b/src/react/LogMonitor.js
@@ -0,0 +1,130 @@
+import React, { PropTypes, findDOMNode } from 'react';
+import LogMonitorEntry from './LogMonitorEntry';
+
+export default class LogMonitor {
+  static propTypes = {
+    computedStates: PropTypes.array.isRequired,
+    stagedActions: PropTypes.array.isRequired,
+    skippedActions: PropTypes.object.isRequired,
+    reset: PropTypes.func.isRequired,
+    commit: PropTypes.func.isRequired,
+    rollback: PropTypes.func.isRequired,
+    sweep: PropTypes.func.isRequired,
+    toggleAction: PropTypes.func.isRequired,
+    select: PropTypes.func.isRequired
+  };
+
+  static defaultProps = {
+    select: (state) => state
+  };
+
+  componentWillReceiveProps(nextProps) {
+    if (this.props.stagedActions.length < nextProps.stagedActions.length) {
+      const scrollableNode = findDOMNode(this).parentElement;
+      const { scrollTop, offsetHeight, scrollHeight } = scrollableNode;
+
+      this.scrollDown = Math.abs(
+        scrollHeight - (scrollTop + offsetHeight)
+      ) < 20;
+    } else {
+      this.scrollDown = false;
+    }
+  }
+
+  componentDidUpdate(prevProps) {
+    if (
+      prevProps.stagedActions.length < this.props.stagedActions.length &&
+      this.scrollDown
+    ) {
+      const scrollableNode = findDOMNode(this).parentElement;
+      const { offsetHeight, scrollHeight } = scrollableNode;
+
+      scrollableNode.scrollTop = scrollHeight - offsetHeight;
+      this.scrollDown = false;
+    }
+  }
+
+  handleRollback() {
+    this.props.rollback();
+  }
+
+  handleSweep() {
+    this.props.sweep();
+  }
+
+  handleCommit() {
+    this.props.commit();
+  }
+
+  handleToggleAction(index) {
+    this.props.toggleAction(index);
+  }
+
+  handleReset() {
+    this.props.reset();
+  }
+
+  render() {
+    const elements = [];
+    const { skippedActions, stagedActions, computedStates, select } = this.props;
+
+    for (let i = 0; i < stagedActions.length; i++) {
+      const action = stagedActions[i];
+      const { state, error } = computedStates[i];
+
+      elements.push(
+        <LogMonitorEntry key={i}
+                         index={i}
+                         select={select}
+                         action={action}
+                         state={state}
+                         collapsed={skippedActions[i]}
+                         error={error}
+                         onActionClick={::this.handleToggleAction} />
+      );
+    }
+
+    return (
+      <div style={{
+        fontFamily: 'monospace',
+        position: 'relative'
+      }}>
+        <div>
+          <a onClick={::this.handleReset}
+             style={{ textDecoration: 'underline', cursor: 'hand' }}>
+            Reset
+          </a>
+        </div>
+        {elements}
+        <div>
+          {computedStates.length > 1 &&
+            <a onClick={::this.handleRollback}
+               style={{ textDecoration: 'underline', cursor: 'hand' }}>
+              Rollback
+            </a>
+          }
+          {Object.keys(skippedActions).some(key => skippedActions[key]) &&
+            <span>
+              {' • '}
+              <a onClick={::this.handleSweep}
+                 style={{ textDecoration: 'underline', cursor: 'hand' }}>
+                Sweep
+              </a>
+            </span>
+          }
+          {computedStates.length > 1 &&
+            <span>
+              <span>
+              {' • '}
+              </span>
+              <a onClick={::this.handleCommit}
+                 style={{ textDecoration: 'underline', cursor: 'hand' }}>
+                Commit
+              </a>
+            </span>
+          }
+        </div>
+      </div>
+    );
+  }
+}
diff --git a/src/react/LogMonitorEntry.js b/src/react/LogMonitorEntry.js
new file mode 100644
index 00000000..b122a64a
--- /dev/null
+++ b/src/react/LogMonitorEntry.js
@@ -0,0 +1,121 @@
+import React, { PropTypes } from 'react';
+
+function hsvToRgb(h, s, v) {
+  const i = Math.floor(h);
+  const f = h - i;
+  const p = v * (1 - s);
+  const q = v * (1 - f * s);
+  const t = v * (1 - (1 - f) * s);
+  const mod = i % 6;
+  const r = [v, q, p, p, t, v][mod];
+  const g = [t, v, v, q, p, p][mod];
+  const b = [p, p, t, v, v, q][mod];
+
+  return {
+    r: Math.round(r * 255),
+    g: Math.round(g * 255),
+    b: Math.round(b * 255)
+  };
+}
+
+function colorFromString(token) {
+  const splitToken = token.split('');
+  const finalToken = splitToken.concat(splitToken.reverse());
+
+  const number = finalToken.reduce(
+    (sum, char) => sum + char.charCodeAt(0),
+    0
+  ) * Math.abs(Math.sin(token.length));
+
+  const h = Math.round((number * (180 / Math.PI) * token.length) % 360);
+  const s = number % 100 / 100;
+  const v = 1;
+
+  return hsvToRgb(h, s, v);
+}
+
+export default class LogMonitorEntry {
+  static propTypes = {
+    index: PropTypes.number.isRequired,
+    state: PropTypes.object.isRequired,
+    action: PropTypes.object.isRequired,
+    select: PropTypes.func.isRequired,
+    error: PropTypes.string,
+    onActionClick: PropTypes.func.isRequired,
+    collapsed: PropTypes.bool
+  };
+
+  printState(state, error) {
+    let errorText = error;
+    if (!errorText) {
+      try {
+        return JSON.stringify(this.props.select(state));
+      } catch (err) {
+        errorText = 'Error selecting state.';
+      }
+    }
+
+    return (
+      <span style={{
+        fontStyle: 'italic'
+      }}>
+        ({errorText})
+      </span>
+    );
+  }
+
+  handleActionClick() {
+    const { index, onActionClick } = this.props;
+    if (index > 0) {
+      onActionClick(index);
+    }
+  }
+
+  render() {
+    const { index, error, action, state, collapsed } = this.props;
+    const { r, g, b } = colorFromString(action.type);
+
+    return (
+      <div style={{
+        textDecoration: collapsed ? 'line-through' : 'none'
+      }}>
+        <a onClick={::this.handleActionClick}
+           style={{
+             opacity: collapsed ? 0.5 : 1,
+             marginTop: '1em',
+             display: 'block',
+             paddingBottom: '1em',
+             paddingTop: '1em',
+             color: `rgb(${r}, ${g}, ${b})`,
+             cursor: (index > 0) ? 'hand' : 'default',
+             WebkitUserSelect: 'none'
+           }}>
+          {JSON.stringify(action)}
+        </a>
+
+        {!collapsed &&
+          <p style={{
+            textAlign: 'center',
+            transform: 'rotate(180deg)'
+          }}>
+            ⇧
+          </p>
+        }
+
+        {!collapsed &&
+          <div style={{
+            paddingBottom: '1em',
+            paddingTop: '1em',
+            color: 'lightyellow'
+          }}>
+            {this.printState(state, error)}
+          </div>
+        }
+
+        <hr style={{
+          marginBottom: '2em'
+        }} />
+      </div>
+    );
+  }
+}
diff --git a/src/react/index.js b/src/react/index.js
new file mode 100644
index 00000000..cce0e96d
--- /dev/null
+++ b/src/react/index.js
@@ -0,0 +1,6 @@
+import React from 'react';
+import createDevTools from '../createDevTools';
+
+export const DevTools = createDevTools(React);
+export { default as LogMonitor } from './LogMonitor';
+export { default as DebugPanel } from './DebugPanel';
diff --git a/src/react/native/index.js b/src/react/native/index.js
new file mode 100644
index 00000000..0ffdd02f
--- /dev/null
+++ b/src/react/native/index.js
@@ -0,0 +1 @@
+// TODO
\ No newline at end of file