diff --git a/.eslintrc.yml b/.eslintrc.yml
new file mode 100644
index 0000000..ef6836d
--- /dev/null
+++ b/.eslintrc.yml
@@ -0,0 +1,254 @@
+env:
+  browser: true
+  commonjs: true
+  es6: true
+  node: true
+extends: 'eslint:recommended'
+rules:
+  accessor-pairs: error
+  array-bracket-newline: error
+  array-bracket-spacing: error
+  array-callback-return: 'off'
+  array-element-newline: error
+  arrow-body-style: error
+  arrow-parens: error
+  arrow-spacing: error
+  block-scoped-var: error
+  block-spacing:
+    - error
+    - never
+  brace-style:
+    - error
+    - stroustrup
+  callback-return: error
+  camelcase: error
+  capitalized-comments:
+    - error
+    - never
+  class-methods-use-this: error
+  comma-dangle: error
+  comma-spacing: 'off'
+  comma-style:
+    - error
+    - last
+  complexity: error
+  computed-property-spacing:
+    - error
+    - never
+  consistent-return: error
+  consistent-this: error
+  curly: 'off'
+  default-case: error
+  dot-location: error
+  dot-notation: 'off'
+  eol-last: error
+  eqeqeq: error
+  for-direction: error
+  func-call-spacing: error
+  func-name-matching: error
+  func-names:
+    - error
+    - never
+  func-style:
+    - error
+    - declaration
+  function-paren-newline: error
+  generator-star-spacing: error
+  getter-return: error
+  global-require: error
+  guard-for-in: 'off'
+  handle-callback-err: error
+  id-blacklist: error
+  id-length: 'off'
+  id-match: error
+  implicit-arrow-linebreak: error
+  indent: 'off'
+  indent-legacy: 'off'
+  init-declarations: 'off'
+  jsx-quotes: error
+  key-spacing: 'off'
+  keyword-spacing: 'off'
+  line-comment-position: 'off'
+  linebreak-style:
+    - error
+    - unix
+  lines-around-comment: error
+  lines-around-directive: error
+  lines-between-class-members: error
+  max-depth: error
+  max-len: 'off'
+  max-lines: error
+  max-nested-callbacks: error
+  max-params: error
+  max-statements: 'off'
+  max-statements-per-line: error
+  multiline-comment-style:
+    - error
+    - separate-lines
+  multiline-ternary: error
+  new-cap: error
+  new-parens: error
+  newline-after-var:
+    - error
+    - never
+  newline-before-return: 'off'
+  newline-per-chained-call: error
+  no-alert: error
+  no-array-constructor: error
+  no-await-in-loop: error
+  no-bitwise: error
+  no-buffer-constructor: error
+  no-caller: error
+  no-catch-shadow: error
+  no-confusing-arrow: error
+  no-continue: error
+  no-div-regex: error
+  no-duplicate-imports: error
+  no-else-return: error
+  no-empty-function: error
+  no-eq-null: error
+  no-eval: error
+  no-extend-native: error
+  no-extra-bind: error
+  no-extra-label: error
+  no-extra-parens: error
+  no-floating-decimal: error
+  no-implicit-coercion: error
+  no-implicit-globals: error
+  no-implied-eval: error
+  no-inline-comments: 'off'
+  no-inner-declarations:
+    - error
+    - functions
+  no-invalid-this: error
+  no-iterator: error
+  no-label-var: error
+  no-labels: error
+  no-lone-blocks: error
+  no-lonely-if: error
+  no-loop-func: error
+  no-magic-numbers: 'off'
+  no-mixed-operators: error
+  no-mixed-requires: error
+  no-multi-assign: error
+  no-multi-spaces:
+    - error
+    - ignoreEOLComments: true
+  no-multi-str: error
+  no-multiple-empty-lines: error
+  no-native-reassign: error
+  no-negated-condition: error
+  no-negated-in-lhs: error
+  no-nested-ternary: error
+  no-new: error
+  no-new-func: error
+  no-new-object: error
+  no-new-require: error
+  no-new-wrappers: error
+  no-octal-escape: error
+  no-param-reassign: error
+  no-path-concat: error
+  no-plusplus: error
+  no-process-env: error
+  no-process-exit: error
+  no-proto: error
+  no-prototype-builtins: 'off'
+  no-restricted-globals: error
+  no-restricted-imports: error
+  no-restricted-modules: error
+  no-restricted-properties: error
+  no-restricted-syntax: error
+  no-return-assign: error
+  no-return-await: error
+  no-script-url: error
+  no-self-compare: error
+  no-sequences: error
+  no-shadow: error
+  no-shadow-restricted-names: error
+  no-spaced-func: error
+  no-sync: error
+  no-tabs: error
+  no-template-curly-in-string: error
+  no-ternary: error
+  no-throw-literal: error
+  no-trailing-spaces: 'off'
+  no-undef-init: error
+  no-undefined: error
+  no-underscore-dangle: error
+  no-unmodified-loop-condition: error
+  no-unneeded-ternary: error
+  no-unused-expressions: error
+  no-use-before-define: error
+  no-useless-call: error
+  no-useless-computed-key: error
+  no-useless-concat: error
+  no-useless-constructor: error
+  no-useless-rename: error
+  no-useless-return: error
+  no-var: 'off'
+  no-void: error
+  no-warning-comments: error
+  no-whitespace-before-property: error
+  no-with: error
+  nonblock-statement-body-position: error
+  object-curly-newline: error
+  object-curly-spacing: error
+  object-property-newline: error
+  object-shorthand: 'off'
+  one-var: 'off'
+  one-var-declaration-per-line: error
+  operator-assignment: error
+  operator-linebreak: error
+  padded-blocks: 'off'
+  padding-line-between-statements: error
+  prefer-arrow-callback: 'off'
+  prefer-const: error
+  prefer-destructuring: error
+  prefer-numeric-literals: error
+  prefer-promise-reject-errors: error
+  prefer-reflect: 'off'
+  prefer-rest-params: error
+  prefer-spread: error
+  prefer-template: 'off'
+  quote-props: 'off'
+  quotes: 'off'
+  radix: error
+  require-await: error
+  require-jsdoc: 'off'
+  rest-spread-spacing: error
+  semi: 'off'
+  semi-spacing: error
+  semi-style:
+    - error
+    - last
+  sort-imports: error
+  sort-keys:
+    - error
+    - desc
+  sort-vars: error
+  space-before-blocks: 'off'
+  space-before-function-paren: 'off'
+  space-in-parens:
+    - error
+    - never
+  space-infix-ops: error
+  space-unary-ops: error
+  spaced-comment:
+    - error
+    - always
+  strict: error
+  switch-colon-spacing: error
+  symbol-description: error
+  template-curly-spacing: error
+  template-tag-spacing: error
+  unicode-bom:
+    - error
+    - never
+  valid-jsdoc: error
+  vars-on-top: 'off'
+  wrap-iife: error
+  wrap-regex: error
+  yield-star-spacing: error
+  yoda:
+    - error
+    - never
diff --git a/.travis.yml b/.travis.yml
index 879f80b..4d5ed67 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -7,6 +7,4 @@ git:
 cache:
   directories:
   - node_modules
-env:
-  global:
-    secure: RFDw3qN8IsyPsA5Cy6SJtJDTOtrAmp4NT4bhkGiJUGld4ChNE25hYigmV9PVunFv0ttAx9UFXEmEs9jCVA39L93L1aYzLDRwZMJgp9n12B+lATNkljVvZiiTijL9x4YI16Bsx4vieRPo8FNL3oErB0i3a+0zLFTADk4SzqN6Lp4xk1nssxBPCVr6EYCNlQFK26HvCqUgbhDKb5egfcyHWSO9RMC565oTkbMp1kO6kaK/+le1Ca5veQnquNvtTCjmVThzc5HHznxYi5yP3tP2FZzM9LSQoLreqgExvXzTj0id4Cww3evaooefPGVqGXgDp17DhSqdnfiqsOuuxuXQ2yc7k+vNytZh3G2rvHX5itqDKRi9BlOM5oli4xyELK0zH5grE6COBJlTS57I0r9uyKoreu09Z9CH1+zol3jmZLIYhp1zovS1NflfzYQmhsmzixfVXfFvNI95VIbnqciuvrQaTDoyOcOi8kHyLUJgg1CACKZfLx4ydcBC8jaosjacQjQEl6OhbqEt5kH/SVAF52LrA0uKW8RzZyy40vX5/w24C/ob+HoMISAQqtXq2RtvD6jEvcNMczHNsHkNbqkr6Bqi74DUu9hrT2Z3uzwsHe7wKprpEpEEhdI636ZIN8RUE44nmGgoDleqPGrnx2UsmgmPfe6AxYN7y5CthnVprr8=
+
diff --git a/package.json b/package.json
index 6535d26..5b7887c 100644
--- a/package.json
+++ b/package.json
@@ -1,16 +1,21 @@
 {
   "name": "twiz-client-utils",
   "version": "1.0.0",
-  "description": "utilities functions for twiz-client",
+  "description": "CustomError and percentEncode functions for twiz-client",
   "main": "src/utils.js",
+
   "scripts": {
+    "lint":"eslint src/utils.js",
     "tap": "tap -Rspec test/*.js",
     "test": "nyc npm run tap && nyc report --reporter=text-lcov | coveralls"
   },
+
   "author": "github.com/gits2501",
   "license": "MIT",
+
   "devDependencies": {
     "coveralls": "^3.0.1",
+    "eslint": "^4.19.1",
     "nyc": "^11.7.1",
     "tap": "^11.1.3"
   }