diff --git a/Gruntfile.js b/Gruntfile.js
index e9b938c00..0183f688e 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -83,6 +83,7 @@ module.exports = function(grunt) {
           'js/shell.js', // shell must be loaded before moment due to the way moment loads in a commonjs env
           'lib/moment/min/moment.min.js',
           'lib/qrcode-generator/js/qrcode.js',
+          'lib/underscore/underscore.js',
           'lib/bitcore.js',
           'lib/crypto-js/rollups/sha256.js',
           'lib/crypto-js/rollups/pbkdf2.js',
diff --git a/bower.json b/bower.json
index d58a6e511..331b065ca 100644
--- a/bower.json
+++ b/bower.json
@@ -21,7 +21,8 @@
     "socket.io-client": ">=1.0.0",
     "mousetrap": "1.4.6",
     "zeroclipboard": "~1.3.5",
-    "ng-idle": "*"
+    "ng-idle": "*",
+    "underscore": "~1.7.0"
   },
   "resolutions": {
     "angular": "=1.2.19"
diff --git a/js/app.js b/js/app.js
index e90e55275..fcc03a23a 100644
--- a/js/app.js
+++ b/js/app.js
@@ -1,20 +1,20 @@
 'use strict';
 
 var copay = require('copay');
+var _ = require('underscore');
 var config = defaultConfig;
 var localConfig = JSON.parse(localStorage.getItem('config'));
+
 if (localConfig) {
   var cmv = copay.version.split('.')[1];
   var lmv = localConfig.version ? localConfig.version.split('.')[1] : '-1';
   if (cmv === lmv) {
-    for (name in localConfig) {
-      if (localConfig.hasOwnProperty(name)) {
-        if (name === 'networkName' && config['forceNetwork']) {
-          continue;
-        }
-        config[name] = localConfig[name];
+    _.each(localConfig, function(value, key) {
+      if (key === 'networkName' && config['forceNetwork']) {
+        return;
       }
-    }
+      config[name] = value;
+    });
   }
 }
 
diff --git a/js/models/core/TxProposal.js b/js/models/core/TxProposal.js
index 2c7b6d02b..2340bde8d 100644
--- a/js/models/core/TxProposal.js
+++ b/js/models/core/TxProposal.js
@@ -1,6 +1,7 @@
 'use strict';
 
 var bitcore = require('bitcore');
+var _ = require('underscore');
 var util = bitcore.util;
 var Transaction = bitcore.Transaction;
 var BuilderMockV0 = require('./BuilderMockV0');;
@@ -51,22 +52,19 @@ TxProposal.prototype._check = function() {
   if (!tx.ins.length)
     throw new Error('Invalid tx proposal: no ins');
 
-  for (var i in tx.ins) {
-    var scriptSig = tx.ins[i].s;
+  _.each(tx.ins, function(value, index) {
+    var scriptSig = value.s;
     if (!scriptSig || !scriptSig.length) {
       throw new Error('Invalid tx proposal: no signatures');
     }
-  }
-
-  for (var i = 0; i < tx.ins.length; i++) {
-    var hashType = tx.getHashType(i);
+    var hashType = tx.getHashType(index);
     if (hashType && hashType !== Transaction.SIGHASH_ALL)
       throw new Error('Invalid tx proposal: bad signatures');
-  }
+  });
 };
 
 TxProposal.prototype.rejectCount = function() {
-  return Object.keys(this.rejectedBy).length;
+  return _.size(this.rejectedBy);
 };
 
 TxProposal.prototype.isPending = function(maxRejectCount) {
diff --git a/js/models/core/Wallet.js b/js/models/core/Wallet.js
index 0a9785516..272e27d11 100644
--- a/js/models/core/Wallet.js
+++ b/js/models/core/Wallet.js
@@ -1,6 +1,7 @@
 'use strict';
 
 var EventEmitter = require('events').EventEmitter;
+var _ = require('underscore');
 var async = require('async');
 var preconditions = require('preconditions').singleton();
 var util = require('util');
@@ -34,8 +35,7 @@ function Wallet(opts) {
     'publicKeyRing', 'txProposals', 'privateKey', 'version',
     'reconnectDelay'
   ].forEach(function(k) {
-    preconditions.checkArgument(typeof opts[k] !== 'undefined',
-      'missing required option for Wallet: ' + k);
+    preconditions.checkArgument(!_.isUndefined(opts[k]), 'missing required option for Wallet: ' + k);
     self[k] = opts[k];
   });
   preconditions.checkArgument(!copayConfig.forceNetwork || this.getNetworkName() === copayConfig.networkName,
@@ -161,7 +161,7 @@ Wallet.prototype._getKeyMap = function(txp) {
   for (var i in txp._inputSigners) {
     var keyMap = this.publicKeyRing.copayersForPubkeys(txp._inputSigners[i], txp.inputChainPaths);
 
-    if (Object.keys(keyMap).length !== txp._inputSigners[i].length)
+    if (_.size(keyMap) !== _.size(txp._inputSigners[i]))
       throw new Error('Signature does not match known copayers');
 
     for (var j in keyMap) {
@@ -170,8 +170,8 @@ Wallet.prototype._getKeyMap = function(txp) {
 
     // From here -> only to check that all inputs have the same sigs
     var inSigArr = [];
-    Object.keys(keyMap).forEach(function(k) {
-      inSigArr.push(keyMap[k]);
+    _.each(keyMap, function(value, key) {
+      inSigArr.push(value);
     });
     var inSig = JSON.stringify(inSigArr.sort());
     if (i === '0') {
@@ -299,7 +299,7 @@ Wallet.prototype._onAddressBook = function(senderId, data) {
 
 Wallet.prototype.updateTimestamp = function(ts) {
   preconditions.checkArgument(ts);
-  preconditions.checkArgument(typeof ts === 'number');
+  preconditions.checkArgument(_.isNumber(ts));
   this.lastTimestamp = ts;
   this.store();
 };
@@ -315,7 +315,7 @@ Wallet.prototype._onData = function(senderId, data, ts) {
   preconditions.checkArgument(data);
   preconditions.checkArgument(data.type);
   preconditions.checkArgument(ts);
-  preconditions.checkArgument(typeof ts === 'number');
+  preconditions.checkArgument(_.isNumber(ts));
 
   log.debug('RECV', senderId, data);
 
@@ -582,11 +582,11 @@ Wallet.prototype.send = function(recipients, obj) {
 };
 
 Wallet.prototype.sendAllTxProposals = function(recipients) {
-  var ntxids = this.txProposals.getNtxids();
-  for (var i in ntxids) {
-    var ntxid = ntxids[i];
-    this.sendTxProposal(ntxid, recipients);
-  }
+  var ntxids = this.txProposals.getNtxids(),
+        that = this;
+  _.each(ntxids, function(ntxid, key) {
+    that.sendTxProposal(ntxid, recipients);
+  });
 };
 
 Wallet.prototype.sendTxProposal = function(ntxid, recipients) {
@@ -730,7 +730,7 @@ Wallet.prototype.reject = function(ntxid) {
 };
 
 Wallet.prototype.sign = function(ntxid, cb) {
-  preconditions.checkState(typeof this.getMyCopayerId() !== 'undefined');
+  preconditions.checkState(!_.isUndefined(this.getMyCopayerId()));
   var self = this;
   setTimeout(function() {
     var myId = self.getMyCopayerId();
@@ -805,7 +805,7 @@ Wallet.prototype.sendTx = function(ntxid, cb) {
 Wallet.prototype.createPaymentTx = function(options, cb) {
   var self = this;
 
-  if (typeof options === 'string') {
+  if (_.isString(options)) {
     options = {
       uri: options
     };
@@ -849,7 +849,7 @@ Wallet.prototype.fetchPaymentTx = function(options, cb) {
   var self = this;
 
   options = options || {};
-  if (typeof options === 'string') {
+  if (_.isString(options)) {
     options = {
       uri: options
     };
@@ -1160,7 +1160,7 @@ Wallet.prototype.createPaymentTxSync = function(options, merchantData, unspent)
     }
   };
 
-  if (typeof opts.spendUnconfirmed === 'undefined') {
+  if (_.isUndefined(opts.spendUnconfirmed)) {
     opts.spendUnconfirmed = this.spendUnconfirmed;
   }
 
@@ -1270,7 +1270,7 @@ Wallet.prototype.createPaymentTxSync = function(options, merchantData, unspent)
 Wallet.prototype.verifyPaymentRequest = function(ntxid) {
   if (!ntxid) return false;
 
-  var txp = typeof ntxid !== 'object' ? this.txProposals.get(ntxid) : ntxid;
+  var txp = _.isObject(ntxid) ? ntxid : this.txProposals.get(ntxid);
 
   // If we're not a payment protocol proposal, ignore.
   if (!txp.merchant) return true;
@@ -1443,16 +1443,7 @@ Wallet.prototype.getAddressesInfo = function(opts) {
 
 Wallet.prototype.addressIsOwn = function(addrStr, opts) {
   var addrList = this.getAddressesStr(opts);
-  var l = addrList.length;
-  var ret = false;
-
-  for (var i = 0; i < l; i++) {
-    if (addrList[i] === addrStr) {
-      ret = true;
-      break;
-    }
-  }
-  return ret;
+  return _.any(addrList, function(value) { return value === addrStr; });
 };
 
 //retunrs values in SATOSHIs
@@ -1476,10 +1467,10 @@ Wallet.prototype.getBalance = function(cb) {
 
     // we multiply and divide by BIT to avoid rounding errors when adding
     for (var a in balanceByAddr) {
-      balanceByAddr[a] = parseInt(balanceByAddr[a].toFixed(0));
+      balanceByAddr[a] = parseInt(balanceByAddr[a].toFixed(0), 10);
     }
 
-    balance = parseInt(balance.toFixed(0));
+    balance = parseInt(balance.toFixed(0), 10);
 
     for (var i = 0; i < safeUnspent.length; i++) {
       var u = safeUnspent[i];
@@ -1487,7 +1478,7 @@ Wallet.prototype.getBalance = function(cb) {
       safeBalance += amt;
     }
 
-    safeBalance = parseInt(safeBalance.toFixed(0));
+    safeBalance = parseInt(safeBalance.toFixed(0), 10);
     return cb(null, balance, balanceByAddr, safeBalance);
   });
 };
@@ -1529,7 +1520,7 @@ Wallet.prototype.getUnspent = function(cb) {
 Wallet.prototype.createTx = function(toAddress, amountSatStr, comment, opts, cb) {
   var self = this;
 
-  if (typeof amountSatStr === 'function') {
+  if (_.isFunction(amountSatStr)) {
     var cb = amountSatStr;
     var merchant = toAddress;
     return this.createPaymentTx({
@@ -1537,7 +1528,7 @@ Wallet.prototype.createTx = function(toAddress, amountSatStr, comment, opts, cb)
     }, cb);
   }
 
-  if (typeof comment === 'function') {
+  if (_.isFunction(comment)) {
     var cb = comment;
     var merchant = toAddress;
     var comment = amountSatStr;
@@ -1547,13 +1538,13 @@ Wallet.prototype.createTx = function(toAddress, amountSatStr, comment, opts, cb)
     }, cb);
   }
 
-  if (typeof opts === 'function') {
+  if (_.isFunction(opts)) {
     cb = opts;
     opts = {};
   }
   opts = opts || {};
 
-  if (typeof opts.spendUnconfirmed === 'undefined') {
+  if (_.isUndefined(opts.spendUnconfirmed)) {
     opts.spendUnconfirmed = this.spendUnconfirmed;
   }
 
@@ -1816,7 +1807,7 @@ Wallet.prototype.verifySignedJson = function(senderId, payload, signature) {
 // }
 
 Wallet.request = function(options, callback) {
-  if (typeof options === 'string') {
+  if (_.isString(options)) {
     options = {
       uri: options
     };
diff --git a/karma.conf.js b/karma.conf.js
index 74d8f7377..bc467f9bb 100644
--- a/karma.conf.js
+++ b/karma.conf.js
@@ -29,6 +29,7 @@ module.exports = function(config) {
       'lib/angular-foundation/mm-foundation.min.js',
       'lib/angular-foundation/mm-foundation-tpls.min.js',
       'lib/bitcore.js',
+      'lib/underscore/underscore.js',
       'lib/crypto-js/rollups/sha256.js',
       'lib/crypto-js/rollups/pbkdf2.js',
       'lib/crypto-js/rollups/aes.js',
diff --git a/package.json b/package.json
index 258a25603..c970b0737 100644
--- a/package.json
+++ b/package.json
@@ -17,7 +17,8 @@
     "optimist": "^0.6.1",
     "preconditions": "^1.0.7",
     "request": "^2.40.0",
-    "sinon": "1.9.1"
+    "sinon": "1.9.1",
+    "underscore": "^1.7.0"
   },
   "scripts": {
     "shell": "node shell/scripts/launch.js",
@@ -72,7 +73,7 @@
     "travis-cov": "0.2.5",
     "uglifyify": "1.2.3",
     "crypto-js": "3.1.2",
-    "shelljs":"0.3.0",
+    "shelljs": "0.3.0",
     "browser-request": "0.3.2",
     "request": "2.40.0"
   },
diff --git a/util/build.js b/util/build.js
index bcd6f5ec1..c3b8b7bd6 100644
--- a/util/build.js
+++ b/util/build.js
@@ -43,6 +43,9 @@ var createBundle = function(opts) {
   b.require('browser-request', {
     expose: 'request'
   });
+  b.require('underscore', {
+    expose: 'underscore'
+  });
 
   b.require('./copay', {
     expose: 'copay'