diff --git a/app/scripts/controllers/detect-tokens.js b/app/scripts/controllers/detect-tokens.js
new file mode 100644
index 000000000..a7ddace19
--- /dev/null
+++ b/app/scripts/controllers/detect-tokens.js
@@ -0,0 +1,97 @@
+const ObservableStore = require('obs-store')
+const { warn } = require('loglevel')
+const contracts = require('eth-contract-metadata')
+const {
+    ROPSTEN,
+    RINKEBY,
+    KOVAN,
+    MAINNET,
+    OCALHOST,
+    } = require('./network/enums')
+
+// By default, poll every 3 minutes
+const DEFAULT_INTERVAL = 180 * 1000
+
+/**
+ * A controller that polls for token exchange
+ * rates based on a user's current token list
+ */
+class DetectTokensController {
+  /**
+   * Creates a DetectTokensController
+   *
+   * @param {Object} [config] - Options to configure controller
+   */
+  constructor ({ interval = DEFAULT_INTERVAL, preferences, network } = {}) {
+    this.preferences = preferences
+    this.interval = interval
+    this.network = network
+  }
+
+   /**
+   * For each token in eth-contract=metada, find check selectedAddress balance.
+   *
+   */
+  async exploreNewTokens () {
+    if (!this.isActive) { return }
+    if (this._network.getProviderConfig().type !== MAINNET) { return }
+    var tokens = this._preferences.store.getState().tokens
+    let detectedTokenAddress, token
+    for (const address in contracts) {
+        const contract = contracts[address]
+        if (contract.erc20 && !(address in tokens)) {
+          detectedTokenAddress = await this.fetchContractAccountBalance(address) 
+          if (detectedTokenAddress) {
+            token = contracts[detectedTokenAddress]
+            this._preferences.addToken(detectedTokenAddress, token['symbol'], token['decimals'])
+          }
+        }
+        // etherscan restriction, 5 request/second, lazy scan
+        setTimeout(() => {}, 200)
+    }
+  }
+
+   /**
+   * Find if selectedAddress has tokens with contract in contractAddress.
+   *
+   * @param {string} contractAddress Hex address of the token contract to explore.
+   * @returns {string} Contract address to be added to tokens.
+   *
+   */
+  async fetchContractAccountBalance (contractAddress) {
+    const address = this._preferences.store.getState().selectedAddress
+    const response = await fetch(`https://api.etherscan.io/api?module=account&action=tokenbalance&contractaddress=${contractAddress}&address=${address}&tag=latest&apikey=NCKS6GTY41KPHWRJB62ES1MDNRBIT174PV`)
+    const parsedResponse = await response.json()
+    if (parsedResponse.result !== '0') {
+      return contractAddress
+    }
+    return null
+  }
+
+  /**
+   * @type {Number}
+   */
+  set interval (interval) {
+    this._handle && clearInterval(this._handle)
+    if (!interval) { return }
+    this._handle = setInterval(() => { this.exploreNewTokens() }, interval)
+  }
+
+    /**
+   * @type {Object}
+   */
+  set preferences (preferences) {
+    if (!preferences) { return }
+    this._preferences = preferences
+  }
+
+      /**
+   * @type {Object}
+   */
+  set network (network) {
+    if (!network) { return }
+    this._network = network
+  }
+}
+
+module.exports = DetectTokensController
diff --git a/app/scripts/metamask-controller.js b/app/scripts/metamask-controller.js
index d40a351a5..37a31a28c 100644
--- a/app/scripts/metamask-controller.js
+++ b/app/scripts/metamask-controller.js
@@ -35,6 +35,7 @@ const TypedMessageManager = require('./lib/typed-message-manager')
 const TransactionController = require('./controllers/transactions')
 const BalancesController = require('./controllers/computed-balances')
 const TokenRatesController = require('./controllers/token-rates')
+const DetectTokensController = require('./controllers/detect-tokens')
 const ConfigManager = require('./lib/config-manager')
 const nodeify = require('./lib/nodeify')
 const accountImporter = require('./account-import-strategies')
@@ -112,6 +113,12 @@ module.exports = class MetamaskController extends EventEmitter {
       preferences: this.preferencesController.store,
     })
 
+    // detect tokens controller 
+    this.detectTokensController = new DetectTokensController({
+      preferences: this.preferencesController,
+      network: this.networkController,
+    })
+
     this.recentBlocksController = new RecentBlocksController({
       blockTracker: this.blockTracker,
       provider: this.provider,
@@ -1276,5 +1283,6 @@ module.exports = class MetamaskController extends EventEmitter {
    */
   set isClientOpenAndUnlocked (active) {
     this.tokenRatesController.isActive = active
+    this.detectTokensController.isActive = active
   }
 }