diff --git a/src/core/components/layout-utils.jsx b/src/core/components/layout-utils.jsx
index 00a4a09d..f80e0c90 100644
--- a/src/core/components/layout-utils.jsx
+++ b/src/core/components/layout-utils.jsx
@@ -129,7 +129,8 @@ export class Select extends React.Component {
     value: PropTypes.any,
     onChange: PropTypes.func,
     multiple: PropTypes.bool,
-    allowEmptyValue: PropTypes.bool
+    allowEmptyValue: PropTypes.bool,
+    className: PropTypes.string
   }
 
   static defaultProps = {
@@ -142,7 +143,7 @@ export class Select extends React.Component {
 
     let value
 
-    if (props.value !== undefined) {
+    if (props.value) {
       value = props.value
     } else {
       value = props.multiple ? [""] : ""
@@ -178,7 +179,7 @@ export class Select extends React.Component {
     let value = this.state.value.toJS ? this.state.value.toJS() : this.state.value
 
     return (
-      <select multiple={ multiple } value={ value } onChange={ this.onChange } >
+      <select className={this.props.className} multiple={ multiple } value={ value } onChange={ this.onChange } >
         { allowEmptyValue ? <option value="">--</option> : null }
         {
           allowedValues.map(function (item, key) {
diff --git a/src/core/components/models.jsx b/src/core/components/models.jsx
index c61ae0c9..86c3256d 100644
--- a/src/core/components/models.jsx
+++ b/src/core/components/models.jsx
@@ -24,8 +24,8 @@ export default class Models extends Component {
     return <section className={ showModels ? "models is-open" : "models"}>
       <h4 onClick={() => layoutActions.show("models", !showModels)}>
         <span>Models</span>
-        <svg width="20" height="20">
-          <use xlinkHref="#large-arrow" />
+        <svg className="arrow" width="20" height="20">
+          <use xlinkHref={showModels ? "#large-arrow-down" : "#large-arrow"} />
         </svg>
       </h4>
       <Collapse isOpened={showModels}>
diff --git a/src/core/json-schema-components.js b/src/core/json-schema-components.js
index bf4ae514..338bd6e3 100644
--- a/src/core/json-schema-components.js
+++ b/src/core/json-schema-components.js
@@ -57,7 +57,8 @@ export class JsonSchema_string extends Component {
 
     if ( enumValue ) {
       const Select = getComponent("Select")
-      return (<Select allowedValues={ enumValue }
+      return (<Select className={ errors.length ? "invalid" : ""}
+                      allowedValues={ enumValue }
                       value={ value }
                       allowEmptyValue={ !required }
                       onChange={ this.onEnumChange }/>)
@@ -121,6 +122,7 @@ export class JsonSchema_array extends PureComponent {
   render() {
     let { getComponent, required, schema, fn } = this.props
 
+    let errors = schema.errors || []
     let itemSchema = fn.inferSchema(schema.items)
 
     const JsonSchemaForm = getComponent("JsonSchemaForm")
@@ -131,19 +133,17 @@ export class JsonSchema_array extends PureComponent {
 
     if ( enumValue ) {
       const Select = getComponent("Select")
-      return (<Select multiple={ true }
+      return (<Select className={ errors.length ? "invalid" : ""}
+                     multiple={ true }
                      value={ value }
                      allowedValues={ enumValue }
                      allowEmptyValue={ !required }
                      onChange={ this.onEnumChange }/>)
     }
 
-    let errors = schema.errors || []
-
     return (
       <div>
-        { !value || value.count() < 1 ?
-          (errors.length ? <span style={{ color: "red", fortWeight: "bold" }}>{ errors[0] }</span> : null) :
+        { !value || value.count() < 1 ? null : 
           value.map( (item,i) => {
             let schema = Object.assign({}, itemSchema)
             if ( errors.length ) {
@@ -153,12 +153,12 @@ export class JsonSchema_array extends PureComponent {
           return (
             <div key={i} className="json-schema-form-item">
               <JsonSchemaForm fn={fn} getComponent={getComponent} value={item} onChange={(val) => this.onItemChange(val, i)} schema={schema} />
-              <Button className="json-schema-form-item-remove" onClick={()=> this.removeItem(i)} > - </Button>
+              <Button className="btn btn-sm json-schema-form-item-remove" onClick={()=> this.removeItem(i)} > - </Button>
             </div>
             )
           }).toArray()
         }
-        <Button className="json-schema-form-item-add" onClick={this.addItem}> Add item </Button>
+        <Button className={`btn btn-sm json-schema-form-item-add ${errors.length ? "invalid" : null}`} onClick={this.addItem}> Add item </Button>
       </div>
     )
   }
@@ -170,12 +170,14 @@ export class JsonSchema_boolean extends Component {
 
   onEnumChange = (val) => this.props.onChange(val)
   render() {
-    let { getComponent, required, value } = this.props
+    let { getComponent, value, schema } = this.props
+    let errors = schema.errors || []
     const Select = getComponent("Select")
 
-    return (<Select value={ String(value) }
+    return (<Select className={ errors.length ? "invalid" : ""}
+                    value={ String(value) }
                     allowedValues={ fromJS(["true", "false"]) }
-                    allowEmptyValue={ !required }
+                    allowEmptyValue={true}
                     onChange={ this.onEnumChange }/>)
   }
 }
diff --git a/src/core/utils.js b/src/core/utils.js
index 95771fb4..9e114dae 100644
--- a/src/core/utils.js
+++ b/src/core/utils.js
@@ -468,6 +468,18 @@ export const validateFile = ( val ) => {
   }
 }
 
+export const validateBoolean = ( val ) => {
+  if ( !(val === "true" || val === "false" || val === true || val === false) ) {
+    return "Value must be a boolean"
+  }
+}
+
+export const validateString = ( val ) => {
+  if ( val && typeof val !== "string" ) {
+    return "Value must be a string"
+  }
+}
+
 // validation of parameters before execute
 export const validateParam = (param, isXml) => {
   let errors = []
@@ -475,52 +487,66 @@ export const validateParam = (param, isXml) => {
   let required = param.get("required")
   let type = param.get("type")
 
-  let stringCheck = type === "string" && !value
-  let arrayCheck = type === "array" && Array.isArray(value) && !value.length
-  let listCheck = type === "array" && Im.List.isList(value) && !value.count()
-  let fileCheck = type === "file" && !(value instanceof win.File)
+  // If the parameter is required OR the parameter has a value (meaning optional, but filled in)
+  // then we should do our validation routine
+  if ( required || value ) {
+    // These checks should evaluate to true if the parameter's value is valid
+    let stringCheck = type === "string" && value && !validateString(value)
+    let arrayCheck = type === "array" && Array.isArray(value) && value.length
+    let listCheck = type === "array" && Im.List.isList(value) && value.count()
+    let fileCheck = type === "file" && value instanceof win.File
+    let booleanCheck = type === "boolean" && !validateBoolean(value)
+    let numberCheck = type === "number" && !validateNumber(value) // validateNumber returns undefined if the value is a number
+    let integerCheck = type === "integer" && !validateInteger(value) // validateInteger returns undefined if the value is an integer
 
-  if ( required && (stringCheck || arrayCheck || listCheck || fileCheck) ) {
-    errors.push("Required field is not provided")
-    return errors
-  }
+    if ( required && !(stringCheck || arrayCheck || listCheck || fileCheck || booleanCheck || numberCheck || integerCheck) ) {
+      errors.push("Required field is not provided")
+      return errors
+    }
 
-  if ( value === null || value === undefined ) {
-    return errors
-  }
+    if ( type === "string" ) {
+      let err = validateString(value)
+      if (!err) return errors
+      errors.push(err)
+    } else if ( type === "boolean" ) {
+      let err = validateBoolean(value)
+      if (!err) return errors
+      errors.push(err)
+    } else if ( type === "number" ) {
+      let err = validateNumber(value)
+      if (!err) return errors
+      errors.push(err)
+    } else if ( type === "integer" ) {
+      let err = validateInteger(value)
+      if (!err) return errors
+      errors.push(err)
+    } else if ( type === "array" ) {
+      let itemType
 
-  if ( type === "number" ) {
-    let err = validateNumber(value)
-    if (!err) return errors
-    errors.push(err)
-  } else if ( type === "integer" ) {
-    let err = validateInteger(value)
-    if (!err) return errors
-    errors.push(err)
-  } else if ( type === "array" ) {
-    let itemType
+      if ( !value.count() ) { return errors }
 
-    if ( !value.count() ) { return errors }
+      itemType = param.getIn(["items", "type"])
 
-    itemType = param.getIn(["items", "type"])
+      value.forEach((item, index) => {
+        let err
 
-    value.forEach((item, index) => {
-      let err
+        if (itemType === "number") {
+          err = validateNumber(item)
+        } else if (itemType === "integer") {
+          err = validateInteger(item)
+        } else if (itemType === "string") {
+          err = validateString(item)
+        }
 
-      if (itemType === "number") {
-        err = validateNumber(item)
-      } else if (itemType === "integer") {
-        err = validateInteger(item)
-      }
-
-      if ( err ) {
-        errors.push({ index: index, error: err})
-      }
-    })
-  } else if ( type === "file" ) {
-    let err = validateFile(value)
-    if (!err) return errors
-    errors.push(err)
+        if ( err ) {
+          errors.push({ index: index, error: err})
+        }
+      })
+    } else if ( type === "file" ) {
+      let err = validateFile(value)
+      if (!err) return errors
+      errors.push(err)
+    }
   }
 
   return errors
diff --git a/src/plugins/add-plugin.md b/src/plugins/add-plugin.md
index 7a77cb30..2e2d52e1 100644
--- a/src/plugins/add-plugin.md
+++ b/src/plugins/add-plugin.md
@@ -20,7 +20,7 @@ SwaggerUI({
 })
 ```
 
-Or if you're updating the core plugins.. you'll add it to [src/js/bootstrap-plugin](https://github.com/SmartBear/swagger-ux/blob/master/src/js/bootstrap-plugin.js)
+Or if you're updating the core plugins.. you'll add it to the base preset: [src/core/presets/base.js](https://github.com/swagger-api/swagger-ui/blob/master/src/core/presets/base.js)
 
 Each Plugin is a function that returns an object. That object will get merged with the `system` and later bound to the state.
 Here is an example of each `type`
diff --git a/src/plugins/topbar/topbar.jsx b/src/plugins/topbar/topbar.jsx
index fd3654bb..ec9db730 100644
--- a/src/plugins/topbar/topbar.jsx
+++ b/src/plugins/topbar/topbar.jsx
@@ -130,7 +130,7 @@ export default class Topbar extends React.Component {
         <div className="wrapper">
           <div className="topbar-wrapper">
             <Link href="#" title="Swagger UX">
-              <img height="30" width="30" src={ Logo } alt="Swagger UX"/>
+              <img height="30" width="30" src={ Logo } alt="Swagger UI"/>
               <span>swagger</span>
             </Link>
             <form className="download-url-wrapper" onSubmit={formOnSubmit}>
diff --git a/src/style/_buttons.scss b/src/style/_buttons.scss
index 2470f8b0..bfb85023 100644
--- a/src/style/_buttons.scss
+++ b/src/style/_buttons.scss
@@ -14,6 +14,11 @@
 
     @include text_headline();
 
+    &.btn-sm {
+        font-size: 12px;
+        padding: 4px 23px;
+    }
+
     &[disabled]
     {
         cursor: not-allowed;
@@ -165,6 +170,9 @@
 button
 {
     cursor: pointer;
-
     outline: none;
+
+    &.invalid {
+        @include invalidFormElement();
+    }
 }
diff --git a/src/style/_form.scss b/src/style/_form.scss
index 185b836e..e54d5438 100644
--- a/src/style/_form.scss
+++ b/src/style/_form.scss
@@ -21,6 +21,10 @@ select
 
         background: #f7f7f7;
     }
+
+    &.invalid {
+        @include invalidFormElement();
+    }
 }
 
 .opblock-body select
@@ -53,12 +57,8 @@ input[type=file]
     border-radius: 4px;
     background: #fff;
 
-    &.invalid
-    {
-        animation: shake .4s 1;
-
-        border-color: $_color-delete;
-        background: lighten($_color-delete, 35%);
+    &.invalid {
+        @include invalidFormElement();
     }
 }
 
diff --git a/src/style/_layout.scss b/src/style/_layout.scss
index 90b9a088..43000ec6 100644
--- a/src/style/_layout.scss
+++ b/src/style/_layout.scss
@@ -508,6 +508,15 @@ body
         {
             margin: 0;
         }
+
+        a
+        {
+            @include text_code(#89bf04);
+            text-decoration: underline;
+            &:hover {
+                color: #81b10c;
+            }
+        }
     }
 }
 
diff --git a/src/style/_mixins.scss b/src/style/_mixins.scss
index a2a27d48..8fd01720 100644
--- a/src/style/_mixins.scss
+++ b/src/style/_mixins.scss
@@ -166,3 +166,9 @@ $browser-context: 16;
         @warn 'Breakpoint mixin supports: tablet, mobile, desktop';
     }
 }
+
+@mixin invalidFormElement() {
+    animation: shake .4s 1;
+    border-color: $_color-delete;
+    background: lighten($_color-delete, 35%);
+}
diff --git a/src/style/_table.scss b/src/style/_table.scss
index 3d58f3d8..d1481709 100644
--- a/src/style/_table.scss
+++ b/src/style/_table.scss
@@ -97,6 +97,10 @@ table
         width: 100%;
         max-width: 340px;
     }
+
+    select {
+        border-width: 1px;
+    }
 }
 
 .parameter__name
diff --git a/test/core/utils.js b/test/core/utils.js
index a63da13d..65ed7435 100644
--- a/test/core/utils.js
+++ b/test/core/utils.js
@@ -176,6 +176,7 @@ describe("utils", function(){
     let result = null
 
     it("validates required strings", function() {
+      // invalid string
       param = fromJS({
         required: true,
         type: "string",
@@ -183,9 +184,39 @@ describe("utils", function(){
       })
       result = validateParam( param, false )
       expect( result ).toEqual( ["Required field is not provided"] )
+
+      // valid string
+      param = fromJS({
+        required: true,
+        type: "string",
+        value: "test string"
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
+    })
+
+    it("validates optional strings", function() {
+      // valid (empty) string
+      param = fromJS({
+        required: false,
+        type: "string",
+        value: ""
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
+
+      // valid string
+      param = fromJS({
+        required: false,
+        type: "string",
+        value: "test"
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
     })
 
     it("validates required files", function() {
+      // invalid file
       param = fromJS({
         required: true,
         type: "file",
@@ -193,9 +224,48 @@ describe("utils", function(){
       })
       result = validateParam( param, false )
       expect( result ).toEqual( ["Required field is not provided"] )
+
+      // valid file
+      param = fromJS({
+        required: true,
+        type: "file",
+        value: new win.File()
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
+    })
+
+    it("validates optional files", function() {
+      // invalid file
+      param = fromJS({
+        required: false,
+        type: "file",
+        value: "not a file"
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( ["Value must be a file"] )
+
+      // valid (empty) file
+      param = fromJS({
+        required: false,
+        type: "file",
+        value: undefined
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
+
+      // valid file
+      param = fromJS({
+        required: false,
+        type: "file",
+        value: new win.File()
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
     })
 
     it("validates required arrays", function() {
+      // invalid (empty) array
       param = fromJS({
         required: true,
         type: "array",
@@ -204,75 +274,51 @@ describe("utils", function(){
       result = validateParam( param, false )
       expect( result ).toEqual( ["Required field is not provided"] )
 
+      // invalid (not an array)
       param = fromJS({
         required: true,
         type: "array",
-        value: []
+        value: undefined
       })
       result = validateParam( param, false )
       expect( result ).toEqual( ["Required field is not provided"] )
-    })
 
-    it("validates numbers", function() {
-      // string instead of a number
+      // invalid array, items do not match correct type
       param = fromJS({
-        required: false,
-        type: "number",
-        value: "test"
+        required: true,
+        type: "array",
+        value: [1],
+        items: {
+          type: "string"
+        }
       })
       result = validateParam( param, false )
-      expect( result ).toEqual( ["Value must be a number"] )
+      expect( result ).toEqual( [{index: 0, error: "Value must be a string"}] )
 
-      // undefined value
+      // valid array, with no 'type' for items
       param = fromJS({
-        required: false,
-        type: "number",
-        value: undefined
+        required: true,
+        type: "array",
+        value: ["1"]
       })
       result = validateParam( param, false )
       expect( result ).toEqual( [] )
 
-      // null value
+      // valid array, items match type
       param = fromJS({
-        required: false,
-        type: "number",
-        value: null
+        required: true,
+        type: "array",
+        value: ["1"],
+        items: {
+          type: "string"
+        }
       })
       result = validateParam( param, false )
       expect( result ).toEqual( [] )
     })
 
-    it("validates integers", function() {
-      // string instead of integer
-      param = fromJS({
-        required: false,
-        type: "integer",
-        value: "test"
-      })
-      result = validateParam( param, false )
-      expect( result ).toEqual( ["Value must be an integer"] )
-
-      // undefined value
-      param = fromJS({
-        required: false,
-        type: "integer",
-        value: undefined
-      })
-      result = validateParam( param, false )
-      expect( result ).toEqual( [] )
-
-      // null value
-      param = fromJS({
-        required: false,
-        type: "integer",
-        value: null
-      })
-      result = validateParam( param, false )
-      expect( result ).toEqual( [] )
-    })
-
-    it("validates arrays", function() {
-      // empty array
+    it("validates optional arrays", function() {
+      // valid, empty array
       param = fromJS({
         required: false,
         type: "array",
@@ -281,7 +327,7 @@ describe("utils", function(){
       result = validateParam( param, false )
       expect( result ).toEqual( [] )
 
-      // numbers
+      // invalid, items do not match correct type
       param = fromJS({
         required: false,
         type: "array",
@@ -293,17 +339,209 @@ describe("utils", function(){
       result = validateParam( param, false )
       expect( result ).toEqual( [{index: 0, error: "Value must be a number"}] )
 
-      // integers
+      // valid
       param = fromJS({
         required: false,
         type: "array",
-        value: ["not", "numbers"],
+        value: ["test"],
         items: {
-          type: "integer"
+          type: "string"
         }
       })
       result = validateParam( param, false )
-      expect( result ).toEqual( [{index: 0, error: "Value must be an integer"}, {index: 1, error: "Value must be an integer"}] )
+      expect( result ).toEqual( [] )
+    })
+
+    it("validates required booleans", function() {
+      // invalid boolean value
+      param = fromJS({
+        required: true,
+        type: "boolean",
+        value: undefined
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( ["Required field is not provided"] )
+
+      // invalid boolean value (not a boolean)
+      param = fromJS({
+        required: true,
+        type: "boolean",
+        value: "test string"
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( ["Required field is not provided"] )
+
+      // valid boolean value
+      param = fromJS({
+        required: true,
+        type: "boolean",
+        value: "true"
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
+
+      // valid boolean value
+      param = fromJS({
+        required: true,
+        type: "boolean",
+        value: false
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
+    })
+
+    it("validates optional booleans", function() {
+      // valid (empty) boolean value
+      param = fromJS({
+        required: false,
+        type: "boolean",
+        value: undefined
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
+
+      // invalid boolean value (not a boolean)
+      param = fromJS({
+        required: false,
+        type: "boolean",
+        value: "test string"
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( ["Value must be a boolean"] )
+
+      // valid boolean value
+      param = fromJS({
+        required: false,
+        type: "boolean",
+        value: "true"
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
+
+      // valid boolean value
+      param = fromJS({
+        required: false,
+        type: "boolean",
+        value: false
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
+    })
+
+    it("validates required numbers", function() {
+      // invalid number, string instead of a number
+      param = fromJS({
+        required: true,
+        type: "number",
+        value: "test"
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( ["Required field is not provided"] )
+
+      // invalid number, undefined value
+      param = fromJS({
+        required: true,
+        type: "number",
+        value: undefined
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( ["Required field is not provided"] )
+
+      // valid number
+      param = fromJS({
+        required: true,
+        type: "number",
+        value: 10
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
+    })
+
+    it("validates optional numbers", function() {
+      // invalid number, string instead of a number
+      param = fromJS({
+        required: false,
+        type: "number",
+        value: "test"
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( ["Value must be a number"] )
+
+      // valid (empty) number
+      param = fromJS({
+        required: false,
+        type: "number",
+        value: undefined
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
+
+      // valid number
+      param = fromJS({
+        required: false,
+        type: "number",
+        value: 10
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
+    })
+
+    it("validates required integers", function() {
+      // invalid integer, string instead of an integer
+      param = fromJS({
+        required: true,
+        type: "integer",
+        value: "test"
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( ["Required field is not provided"] )
+
+      // invalid integer, undefined value
+      param = fromJS({
+        required: true,
+        type: "integer",
+        value: undefined
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( ["Required field is not provided"] )
+
+      // valid integer
+      param = fromJS({
+        required: true,
+        type: "integer",
+        value: 10
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
+    })
+
+    it("validates optional integers", function() {
+      // invalid integer, string instead of an integer
+      param = fromJS({
+        required: false,
+        type: "integer",
+        value: "test"
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( ["Value must be an integer"] )
+
+      // valid (empty) integer
+      param = fromJS({
+        required: false,
+        type: "integer",
+        value: undefined
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
+
+      // valid number
+      param = fromJS({
+        required: false,
+        type: "integer",
+        value: 10
+      })
+      result = validateParam( param, false )
+      expect( result ).toEqual( [] )
     })
   })
 })