diff --git a/.flowconfig b/.flowconfig
index 9a632b96..6897a28b 100644
--- a/.flowconfig
+++ b/.flowconfig
@@ -9,7 +9,7 @@
 .*/node_modules/react-router-redux/.*
 .*/node_modules/oboe/test/.*
 .*/_old/.*
-.*/public/solidity/.*
+.*/public/.*
 
 [libs]
 ./src/flowtype/npm/redux_v3.x.x.js
diff --git a/jest.config.js b/jest.config.js
index d7e1c86a..d9c12451 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -1,11 +1,19 @@
 module.exports = {
     rootDir: './src',
+    automock: false,
+    coverageDirectory: 'coverage/',
     collectCoverage: true,
     testURL: 'http://localhost',
     modulePathIgnorePatterns: [
         'node_modules',
+        'utils/windowUtils.js',
+        'utils/promiseUtils.js',
+        'utils/networkUtils.js',
     ],
     collectCoverageFrom: [
         'utils/**.js',
     ],
+    setupFiles: [
+        './support/setupJest.js',
+    ],
 };
diff --git a/package.json b/package.json
index cca0a91d..27532f4c 100644
--- a/package.json
+++ b/package.json
@@ -32,8 +32,10 @@
         "ethereumjs-units": "^0.2.0",
         "ethereumjs-util": "^5.1.4",
         "git-revision-webpack-plugin": "^3.0.3",
+        "flow-webpack-plugin": "^1.2.0",
         "hdkey": "^0.8.0",
         "html-webpack-plugin": "^3.2.0",
+        "jest-fetch-mock": "^1.6.5",
         "npm-run-all": "^4.1.3",
         "prop-types": "^15.6.2",
         "raf": "^3.4.0",
diff --git a/src/reducers/ModalReducer.js b/src/reducers/ModalReducer.js
index f6e09a51..bd86b456 100644
--- a/src/reducers/ModalReducer.js
+++ b/src/reducers/ModalReducer.js
@@ -57,6 +57,7 @@ export default function modal(state: State = initialState, action: Action): Stat
             if (state.opened && action.device.path === state.device.path && action.device.status === 'occupied') {
                 return initialState;
             }
+
             return state;
 
         case DEVICE.DISCONNECT:
diff --git a/src/support/setupJest.js b/src/support/setupJest.js
new file mode 100644
index 00000000..8e88457e
--- /dev/null
+++ b/src/support/setupJest.js
@@ -0,0 +1 @@
+global.fetch = require('jest-fetch-mock');
\ No newline at end of file
diff --git a/src/utils/__tests__/__snapshots__/device.test.js.snap b/src/utils/__tests__/__snapshots__/device.test.js.snap
index 70364320..8ce5ffe6 100644
--- a/src/utils/__tests__/__snapshots__/device.test.js.snap
+++ b/src/utils/__tests__/__snapshots__/device.test.js.snap
@@ -55,3 +55,13 @@ exports[`device utils get version 4`] = `"1"`;
 exports[`device utils get version 5`] = `"1"`;
 
 exports[`device utils get version 6`] = `"T"`;
+
+exports[`device utils isDisabled 1`] = `false`;
+
+exports[`device utils isDisabled 2`] = `true`;
+
+exports[`device utils isWebUSB 1`] = `true`;
+
+exports[`device utils isWebUSB 2`] = `false`;
+
+exports[`device utils isWebUSB 3`] = `true`;
diff --git a/src/utils/__tests__/__snapshots__/ethUtils.test.js.snap b/src/utils/__tests__/__snapshots__/ethUtils.test.js.snap
index 0ffd930d..f5b70d96 100644
--- a/src/utils/__tests__/__snapshots__/ethUtils.test.js.snap
+++ b/src/utils/__tests__/__snapshots__/ethUtils.test.js.snap
@@ -1,5 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`eth utils calcGasPrice 1`] = `"89090990901"`;
+
 exports[`eth utils decimalToHex 1`] = `"0"`;
 
 exports[`eth utils decimalToHex 2`] = `"1"`;
@@ -8,4 +10,36 @@ exports[`eth utils decimalToHex 3`] = `"2"`;
 
 exports[`eth utils decimalToHex 4`] = `"64"`;
 
-exports[`eth utils decimalToHex 5`] = `"3e7"`;
+exports[`eth utils decimalToHex 5`] = `"2540be3ff"`;
+
+exports[`eth utils hexToDecimal 1`] = `"9999999999"`;
+
+exports[`eth utils hexToDecimal 2`] = `"100"`;
+
+exports[`eth utils hexToDecimal 3`] = `"2"`;
+
+exports[`eth utils hexToDecimal 4`] = `"1"`;
+
+exports[`eth utils hexToDecimal 5`] = `"0"`;
+
+exports[`eth utils hexToDecimal 6`] = `"null"`;
+
+exports[`eth utils padLeftEven 1`] = `"02540be3ff"`;
+
+exports[`eth utils sanitizeHex 1`] = `"0x02540be3ff"`;
+
+exports[`eth utils sanitizeHex 2`] = `"0x01"`;
+
+exports[`eth utils sanitizeHex 3`] = `"0x02"`;
+
+exports[`eth utils sanitizeHex 4`] = `"0x0100"`;
+
+exports[`eth utils sanitizeHex 5`] = `null`;
+
+exports[`eth utils sanitizeHex 6`] = `""`;
+
+exports[`eth utils strip 1`] = `""`;
+
+exports[`eth utils strip 2`] = `"02540be3ff"`;
+
+exports[`eth utils strip 3`] = `"02540be3ff"`;
diff --git a/src/utils/__tests__/__snapshots__/formatUtils.test.js.snap b/src/utils/__tests__/__snapshots__/formatUtils.test.js.snap
new file mode 100644
index 00000000..448a338a
--- /dev/null
+++ b/src/utils/__tests__/__snapshots__/formatUtils.test.js.snap
@@ -0,0 +1,45 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`format utils btckb2satoshib 1`] = `0`;
+
+exports[`format utils btckb2satoshib 2`] = `100000`;
+
+exports[`format utils btckb2satoshib 3`] = `200000`;
+
+exports[`format utils btckb2satoshib 4`] = `10000000`;
+
+exports[`format utils btckb2satoshib 5`] = `99900000`;
+
+exports[`format utils formatAmount 1`] = `"0 btc"`;
+
+exports[`format utils formatAmount 2`] = `"10 mBTC"`;
+
+exports[`format utils formatAmount 3`] = `"0.000005 mBTC"`;
+
+exports[`format utils formatAmount 4`] = `"1e-8 eth"`;
+
+exports[`format utils formatAmount 5`] = `"0.00099999 tau"`;
+
+exports[`format utils formatTime 1`] = `"No time estimate"`;
+
+exports[`format utils formatTime 2`] = `"1 minutes"`;
+
+exports[`format utils formatTime 3`] = `"2 minutes"`;
+
+exports[`format utils formatTime 4`] = `"1 hour 40 minutes"`;
+
+exports[`format utils formatTime 5`] = `"16 hours 39 minutes"`;
+
+exports[`format utils formatTime 6`] = `"45 minutes"`;
+
+exports[`format utils hexToString 1`] = `"test"`;
+
+exports[`format utils hexToString 2`] = `"0001"`;
+
+exports[`format utils hexToString 3`] = `"test99999"`;
+
+exports[`format utils stringToHex 1`] = `"0074006500730074"`;
+
+exports[`format utils stringToHex 2`] = `"0030003000300031"`;
+
+exports[`format utils stringToHex 3`] = `"007400650073007400390039003900390039"`;
diff --git a/src/utils/__tests__/device.test.js b/src/utils/__tests__/device.test.js
index 6bfdc4c6..e135a151 100644
--- a/src/utils/__tests__/device.test.js
+++ b/src/utils/__tests__/device.test.js
@@ -38,6 +38,29 @@ describe('device utils', () => {
         });
     });
 
+    it('isWebUSB', () => {
+        const data = [
+            { transport: { version: ['webusb'] } },
+            { transport: { version: ['aaaaaa'] } },
+            { transport: { version: ['webusb', 'test'] } },
+        ];
+
+        data.forEach((item) => {
+            expect(dUtils.isWebUSB(item.transport)).toMatchSnapshot();
+        });
+    });
+
+    it('isDisabled', () => {
+        const data = [
+            { selectedDevice: { features: null }, devices: [1, 2, 3], transport: { version: ['webusb', 'test'] } },
+            { selectedDevice: { features: null }, devices: [], transport: { version: ['test'] } },
+        ];
+
+        data.forEach((item) => {
+            expect(dUtils.isDisabled(item.selectedDevice, item.devices, item.transport)).toMatchSnapshot();
+        });
+    });
+
     it('get version', () => {
         const deviceMock = [
             { },
diff --git a/src/utils/__tests__/ethUtils.test.js b/src/utils/__tests__/ethUtils.test.js
index 3ff6e2ea..07bd1250 100644
--- a/src/utils/__tests__/ethUtils.test.js
+++ b/src/utils/__tests__/ethUtils.test.js
@@ -1,11 +1,53 @@
+import BigNumber from 'bignumber.js';
 import * as ethUtils from '../ethUtils';
 
 describe('eth utils', () => {
     it('decimalToHex', () => {
-        const input = [0, 1, 2, 100, 999];
+        const input = [0, 1, 2, 100, 9999999999];
 
         input.forEach((entry) => {
             expect(ethUtils.decimalToHex(entry)).toMatchSnapshot();
         });
     });
+
+    it('hexToDecimal', () => {
+        const input = ['2540be3ff', '64', '2', '1', '0', ''];
+
+        input.forEach((entry) => {
+            expect(ethUtils.hexToDecimal(entry)).toMatchSnapshot();
+        });
+    });
+
+    it('padLeftEven', () => {
+        const input = ['2540be3ff'];
+
+        input.forEach((entry) => {
+            expect(ethUtils.padLeftEven(entry)).toMatchSnapshot();
+        });
+    });
+
+    it('sanitizeHex', () => {
+        const input = ['0x2540be3ff', '1', '2', '100', 999, ''];
+
+        input.forEach((entry) => {
+            expect(ethUtils.sanitizeHex(entry)).toMatchSnapshot();
+        });
+    });
+
+
+    it('strip', () => {
+        const input = ['0x', '0x2540be3ff', '2540be3ff'];
+
+        input.forEach((entry) => {
+            expect(ethUtils.strip(entry)).toMatchSnapshot();
+        });
+    });
+
+    it('calcGasPrice', () => {
+        const input = [{ price: new BigNumber(9898998989), limit: '9' }];
+
+        input.forEach((entry) => {
+            expect(ethUtils.calcGasPrice(entry.price, entry.limit)).toMatchSnapshot();
+        });
+    });
 });
diff --git a/src/utils/__tests__/formatUtils.test.js b/src/utils/__tests__/formatUtils.test.js
new file mode 100644
index 00000000..eb1d026d
--- /dev/null
+++ b/src/utils/__tests__/formatUtils.test.js
@@ -0,0 +1,49 @@
+import * as formatUtils from '../formatUtils';
+
+describe('format utils', () => {
+    it('formatAmount', () => {
+        const input = [
+            { amount: 0, coinInfo: { isBitcoin: true, currencyUnits: 'mbtc', shortcut: 'btc' } },
+            { amount: 1000000, coinInfo: { isBitcoin: true, currencyUnits: 'mbtc', shortcut: 'btc' } },
+            { amount: 0.5, coinInfo: { isBitcoin: true, currencyUnits: 'mbtc', shortcut: 'btc' } },
+            { amount: 1, coinInfo: { isBitcoin: false, shortcut: 'eth' } },
+            { amount: 99999, coinInfo: { isBitcoin: false, shortcut: 'tau' } },
+        ];
+
+        input.forEach((entry) => {
+            expect(formatUtils.formatAmount(entry.amount, entry.coinInfo, entry.coinInfo.currencyUnits)).toMatchSnapshot();
+        });
+    });
+
+    it('formatTime', () => {
+        const input = [0, 1, 2, 100, 999, 45];
+
+        input.forEach((entry) => {
+            expect(formatUtils.formatTime(entry)).toMatchSnapshot();
+        });
+    });
+
+    it('btckb2satoshib', () => {
+        const input = [0, 1, 2, 100, 999];
+
+        input.forEach((entry) => {
+            expect(formatUtils.btckb2satoshib(entry)).toMatchSnapshot();
+        });
+    });
+
+    it('stringToHex', () => {
+        const input = ['test', '0001', 'test99999'];
+
+        input.forEach((entry) => {
+            expect(formatUtils.stringToHex(entry)).toMatchSnapshot();
+        });
+    });
+
+    it('hexToString', () => {
+        const input = ['0074006500730074', '0030003000300031', '007400650073007400390039003900390039'];
+
+        input.forEach((entry) => {
+            expect(formatUtils.hexToString(entry)).toMatchSnapshot();
+        });
+    });
+});
diff --git a/src/utils/formatUtils.js b/src/utils/formatUtils.js
index 982c9afb..986b0ee9 100644
--- a/src/utils/formatUtils.js
+++ b/src/utils/formatUtils.js
@@ -1,11 +1,9 @@
 /* @flow */
 
-
-const currencyUnits: string = 'mbtc2';
-
 // TODO: chagne currency units
+const currencyUnitsConstant: string = 'mbtc2';
 
-export const formatAmount = (n: number, coinInfo: any): string => {
+export const formatAmount = (n: number, coinInfo: any, currencyUnits = currencyUnitsConstant): string => {
     const amount = (n / 1e8);
     if (coinInfo.isBitcoin && currencyUnits === 'mbtc' && amount <= 0.1 && n !== 0) {
         const s = (n / 1e5).toString();
diff --git a/src/utils/networkUtils.js b/src/utils/networkUtils.js
index 360168d9..fc29250b 100644
--- a/src/utils/networkUtils.js
+++ b/src/utils/networkUtils.js
@@ -1,6 +1,5 @@
 /* @flow */
 
-
 import 'whatwg-fetch';
 
 export const httpRequest = async (url: string, type: string = 'text'): any => {
@@ -15,16 +14,6 @@ export const httpRequest = async (url: string, type: string = 'text'): any => {
         await response.text();
     }
     throw new Error(`${url} ${response.statusText}`);
-
-
-    // return fetch(url, { credentials: 'same-origin' }).then((response) => {
-    //     if (response.status === 200) {
-
-    //         return response.text().then(result => (json ? JSON.parse(result) : result));
-    //     } else {
-    //         throw new Error(response.statusText);
-    //     }
-    // })
 };
 
 export const JSONRequest = async (url: string): Promise<JSON> => {
diff --git a/webpack/dev.babel.js b/webpack/dev.babel.js
index 42da5afb..f39a2e6e 100644
--- a/webpack/dev.babel.js
+++ b/webpack/dev.babel.js
@@ -1,6 +1,8 @@
 import webpack from 'webpack';
 import GitRevisionPlugin from 'git-revision-webpack-plugin';
 import HtmlWebpackPlugin from 'html-webpack-plugin';
+import FlowWebpackPlugin from 'flow-webpack-plugin';
+
 import { BundleAnalyzerPlugin } from 'webpack-bundle-analyzer';
 
 import {
@@ -47,6 +49,7 @@ module.exports = {
                     {
                         loader: 'stylelint-custom-processor-loader',
                         options: {
+                            emitWarning: true,
                             configPath: '.stylelintrc',
                         },
                     },
@@ -93,6 +96,7 @@ module.exports = {
         new webpack.DefinePlugin({
             COMMITHASH: JSON.stringify(gitRevisionPlugin.commithash()),
         }),
+        new FlowWebpackPlugin(),
         new HtmlWebpackPlugin({
             chunks: ['index'],
             template: `${SRC}index.html`,
diff --git a/webpack/local.babel.js b/webpack/local.babel.js
index 92930de8..8e78c49b 100644
--- a/webpack/local.babel.js
+++ b/webpack/local.babel.js
@@ -115,7 +115,6 @@ module.exports = {
             filename: '[name].css',
             chunkFilename: '[id].css',
         }),
-        
         new HtmlWebpackPlugin({
             chunks: ['index'],
             template: `${SRC}index.html`,
diff --git a/webpack/production.babel.js b/webpack/production.babel.js
index 3761cec3..95932ddd 100644
--- a/webpack/production.babel.js
+++ b/webpack/production.babel.js
@@ -3,6 +3,7 @@ import webpack from 'webpack';
 import GitRevisionPlugin from 'git-revision-webpack-plugin';
 import HtmlWebpackPlugin from 'html-webpack-plugin';
 import CopyWebpackPlugin from 'copy-webpack-plugin';
+import FlowWebpackPlugin from 'flow-webpack-plugin';
 import { SRC, BUILD, PUBLIC } from './constants';
 
 const gitRevisionPlugin = new GitRevisionPlugin();
@@ -66,6 +67,7 @@ module.exports = {
         new webpack.DefinePlugin({
             COMMITHASH: JSON.stringify(gitRevisionPlugin.commithash()),
         }),
+        new FlowWebpackPlugin(),
         new HtmlWebpackPlugin({
             chunks: ['index'],
             template: `${SRC}index.html`,
diff --git a/yarn.lock b/yarn.lock
index af3c54fa..2d274b77 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -255,6 +255,10 @@
   version "0.7.0"
   resolved "https://registry.yarnpkg.com/@sindresorhus/is/-/is-0.7.0.tgz#9a06f4f137ee84d7df0460c1fdb1135ffa6c50fd"
 
+"@types/jest@^23.0.0":
+  version "23.3.2"
+  resolved "https://registry.yarnpkg.com/@types/jest/-/jest-23.3.2.tgz#07b90f6adf75d42c34230c026a2529e56c249dbb"
+
 "@webassemblyjs/ast@1.5.13":
   version "1.5.13"
   resolved "https://registry.yarnpkg.com/@webassemblyjs/ast/-/ast-1.5.13.tgz#81155a570bd5803a30ec31436bc2c9c0ede38f25"
@@ -4306,6 +4310,10 @@ flow-parser@^0.*:
   version "0.72.0"
   resolved "https://registry.yarnpkg.com/flow-parser/-/flow-parser-0.72.0.tgz#6c8041e76ac7d0be1a71ce29c00cd1435fb6013c"
 
+flow-webpack-plugin@^1.2.0:
+  version "1.2.0"
+  resolved "https://registry.yarnpkg.com/flow-webpack-plugin/-/flow-webpack-plugin-1.2.0.tgz#1958821d16135028e391cad5ee2f3a4fa78197ec"
+
 flush-write-stream@^1.0.0:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/flush-write-stream/-/flush-write-stream-1.0.2.tgz#c81b90d8746766f1a609a46809946c45dd8ae417"
@@ -5593,7 +5601,7 @@ isobject@^3.0.0, isobject@^3.0.1:
   version "3.0.1"
   resolved "https://registry.yarnpkg.com/isobject/-/isobject-3.0.1.tgz#4e431e92b11a9731636aa1f9c8d1ccbcfdab78df"
 
-isomorphic-fetch@^2.1.1:
+isomorphic-fetch@^2.1.1, isomorphic-fetch@^2.2.1:
   version "2.2.1"
   resolved "https://registry.yarnpkg.com/isomorphic-fetch/-/isomorphic-fetch-2.2.1.tgz#611ae1acf14f5e81f729507472819fe9733558a9"
   dependencies:
@@ -5785,6 +5793,14 @@ jest-environment-node@^23.4.0:
     jest-mock "^23.2.0"
     jest-util "^23.4.0"
 
+jest-fetch-mock@^1.6.5:
+  version "1.6.5"
+  resolved "https://registry.yarnpkg.com/jest-fetch-mock/-/jest-fetch-mock-1.6.5.tgz#178fa1a937ef6f61fb8e8483b6d4602b17e0d96d"
+  dependencies:
+    "@types/jest" "^23.0.0"
+    isomorphic-fetch "^2.2.1"
+    promise-polyfill "^7.1.1"
+
 jest-get-type@^22.1.0:
   version "22.4.3"
   resolved "https://registry.yarnpkg.com/jest-get-type/-/jest-get-type-22.4.3.tgz#e3a8504d8479342dd4420236b322869f18900ce4"
@@ -8034,6 +8050,10 @@ promise-inflight@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/promise-inflight/-/promise-inflight-1.0.1.tgz#98472870bf228132fcbdd868129bad12c3c029e3"
 
+promise-polyfill@^7.1.1:
+  version "7.1.2"
+  resolved "https://registry.yarnpkg.com/promise-polyfill/-/promise-polyfill-7.1.2.tgz#ab05301d8c28536301622d69227632269a70ca3b"
+
 promise@^7.1.1:
   version "7.3.1"
   resolved "https://registry.yarnpkg.com/promise/-/promise-7.3.1.tgz#064b72602b18f90f29192b8b1bc418ffd1ebd3bf"