diff --git a/src/core/components/layouts/base.jsx b/src/core/components/layouts/base.jsx
index 6cd909bb..1f5a0788 100644
--- a/src/core/components/layouts/base.jsx
+++ b/src/core/components/layouts/base.jsx
@@ -94,8 +94,9 @@ export default class BaseLayout extends React.Component {
             ) : null }
 
             { servers && servers.size ? (
-              <div className="server-container">
+              <div className="global-server-container">
                 <Col className="servers wrapper" mobile={12}>
+                  <span className="servers-title">Server</span>
                   <Servers
                     servers={servers}
                     currentServer={oas3Selectors.selectedServer()}
diff --git a/src/core/components/operation.jsx b/src/core/components/operation.jsx
index 8d4a2683..ea1877f3 100644
--- a/src/core/components/operation.jsx
+++ b/src/core/components/operation.jsx
@@ -22,6 +22,7 @@ export default class Operation extends PureComponent {
     specActions: PropTypes.object.isRequired,
     specSelectors: PropTypes.object.isRequired,
     oas3Actions: PropTypes.object.isRequired,
+    oas3Selectors: PropTypes.object.isRequired,
     layoutActions: PropTypes.object.isRequired,
     layoutSelectors: PropTypes.object.isRequired,
     fn: PropTypes.object.isRequired
@@ -48,7 +49,8 @@ export default class Operation extends PureComponent {
       specSelectors,
       authActions,
       authSelectors,
-      oas3Actions
+      oas3Actions,
+      oas3Selectors
     } = this.props
     let operationProps = this.props.operation
 
@@ -96,6 +98,7 @@ export default class Operation extends PureComponent {
     const Collapse = getComponent( "Collapse" )
     const Markdown = getComponent( "Markdown" )
     const Schemes = getComponent( "schemes" )
+    const OperationServers = getComponent( "OperationServers" )
     const OperationExt = getComponent( "OperationExt" )
 
     const { showExtensions } = getConfigs()
@@ -182,6 +185,21 @@ export default class Operation extends PureComponent {
                 getConfigs={ getConfigs }
               />
 
+              { !tryItOutEnabled ? null :
+                <OperationServers
+                  getComponent={getComponent}
+                  path={path}
+                  method={method}
+                  operationServers={operation.get("servers")}
+                  pathServers={specSelectors.paths().getIn([path, "servers"])}
+                  getSelectedServer={oas3Selectors.selectedServer}
+                  setSelectedServer={oas3Actions.setSelectedServer}
+                  setServerVariableValue={oas3Actions.setServerVariableValue}
+                  getServerVariable={oas3Selectors.serverVariableValue}
+                  getEffectiveServerValue={oas3Selectors.serverEffectiveValue}
+                />
+              }
+
               {!tryItOutEnabled || !allowTryItOut ? null : schemes && schemes.size ? <div className="opblock-schemes">
                     <Schemes schemes={ schemes }
                              path={ path }
diff --git a/src/core/containers/OperationContainer.jsx b/src/core/containers/OperationContainer.jsx
index 74371db1..c939ef38 100644
--- a/src/core/containers/OperationContainer.jsx
+++ b/src/core/containers/OperationContainer.jsx
@@ -35,6 +35,7 @@ export default class OperationContainer extends PureComponent {
     getComponent: PropTypes.func.isRequired,
     authActions: PropTypes.object,
     oas3Actions: PropTypes.object,
+    oas3Selectors: PropTypes.object,
     authSelectors: PropTypes.object,
     specActions: PropTypes.object.isRequired,
     specSelectors: PropTypes.object.isRequired,
@@ -149,6 +150,7 @@ export default class OperationContainer extends PureComponent {
       authActions,
       authSelectors,
       oas3Actions,
+      oas3Selectors,
       fn
     } = this.props
 
@@ -189,6 +191,7 @@ export default class OperationContainer extends PureComponent {
         specActions={ specActions }
         specSelectors={ specSelectors }
         oas3Actions={oas3Actions}
+        oas3Selectors={oas3Selectors}
         layoutActions={ layoutActions }
         layoutSelectors={ layoutSelectors }
         authActions={ authActions }
diff --git a/src/core/plugins/oas3/actions.js b/src/core/plugins/oas3/actions.js
index c9abc855..ac6f244a 100644
--- a/src/core/plugins/oas3/actions.js
+++ b/src/core/plugins/oas3/actions.js
@@ -7,10 +7,10 @@ export const UPDATE_REQUEST_CONTENT_TYPE = "oas3_set_request_content_type"
 export const UPDATE_RESPONSE_CONTENT_TYPE = "oas3_set_response_content_type"
 export const UPDATE_SERVER_VARIABLE_VALUE = "oas3_set_server_variable_value"
 
-export function setSelectedServer (selectedServerUrl) {
+export function setSelectedServer (selectedServerUrl, namespace) {
   return {
     type: UPDATE_SELECTED_SERVER,
-    payload: selectedServerUrl
+    payload: {selectedServerUrl, namespace}
   }
 }
 
@@ -35,9 +35,9 @@ export function setResponseContentType ({ value, path, method }) {
   }
 }
 
-export function setServerVariableValue ({ server, key, val }) {
+export function setServerVariableValue ({ server, namespace, key, val }) {
   return {
     type: UPDATE_SERVER_VARIABLE_VALUE,
-    payload: { server, key, val }
+    payload: { server, namespace, key, val }
   }
 }
diff --git a/src/core/plugins/oas3/components/index.js b/src/core/plugins/oas3/components/index.js
index edd409a1..b37817a8 100644
--- a/src/core/plugins/oas3/components/index.js
+++ b/src/core/plugins/oas3/components/index.js
@@ -4,6 +4,7 @@ import OperationLink from "./operation-link.jsx"
 import Servers from "./servers"
 import RequestBodyEditor from "./request-body-editor"
 import HttpAuth from "./http-auth"
+import OperationServers from "./operation-servers"
 
 export default {
   Callbacks,
@@ -11,5 +12,6 @@ export default {
   RequestBody,
   Servers,
   RequestBodyEditor,
+  OperationServers,
   operationLink: OperationLink
 }
diff --git a/src/core/plugins/oas3/components/operation-servers.jsx b/src/core/plugins/oas3/components/operation-servers.jsx
new file mode 100644
index 00000000..293b346f
--- /dev/null
+++ b/src/core/plugins/oas3/components/operation-servers.jsx
@@ -0,0 +1,102 @@
+import React from "react"
+import PropTypes from "prop-types"
+import ImPropTypes from "react-immutable-proptypes"
+
+export default class OperationServers extends React.Component {
+  static propTypes = {
+    // for self
+    path: PropTypes.string.isRequired,
+    method: PropTypes.string.isRequired,
+    operationServers: ImPropTypes.list,
+    pathServers: ImPropTypes.list,
+    setSelectedServer: PropTypes.func.isRequired,
+    setServerVariableValue: PropTypes.func.isRequired,
+    getSelectedServer: PropTypes.func.isRequired,
+    getServerVariable: PropTypes.func.isRequired,
+    getEffectiveServerValue: PropTypes.func.isRequired,
+
+    // utils
+    getComponent: PropTypes.func.isRequired
+  }
+
+  setSelectedServer = (server) => {
+    const { path, method } = this.props
+    // FIXME: we should be keeping up with this in props/state upstream of us
+    // instead of cheating™ with `forceUpdate`
+    this.forceUpdate()
+    return this.props.setSelectedServer(server, `${path}:${method}`)
+  }
+
+  setServerVariableValue = (obj) => {
+    const { path, method } = this.props
+    // FIXME: we should be keeping up with this in props/state upstream of us
+    // instead of cheating™ with `forceUpdate`
+    this.forceUpdate()
+    return this.props.setServerVariableValue({
+      ...obj,
+      namespace: `${path}:${method}`
+    })
+  }
+
+  getSelectedServer = () => {
+    const { path, method } = this.props
+    return this.props.getSelectedServer(`${path}:${method}`)
+  }
+
+  getServerVariable = (server, key) => {
+    const { path, method } = this.props
+    return this.props.getServerVariable({
+      namespace: `${path}:${method}`,
+      server
+    }, key)
+  }
+
+  getEffectiveServerValue = (server) => {
+    const { path, method } = this.props
+    return this.props.getEffectiveServerValue({
+      server,
+      namespace: `${path}:${method}`
+    })
+  }
+
+  render() {
+    const {
+      // for self
+      operationServers,
+      pathServers,
+
+      // util
+      getComponent
+    } = this.props
+
+    if(!operationServers && !pathServers) {
+      return null
+    }
+
+    const Servers = getComponent("Servers")
+
+    const serversToDisplay = operationServers || pathServers
+    const displaying = operationServers ? "operation" : "path"
+
+    return <div className="opblock-section operation-servers">
+      <div className="opblock-section-header">
+        <div className="tab-header">
+          <h4 className="opblock-title">Servers</h4>
+        </div>
+      </div>
+      <div className="opblock-description-wrapper">
+        <h4 className="message">
+          These {displaying}-level options override the global server options.
+        </h4>
+        <Servers
+          servers={serversToDisplay}
+          currentServer={this.getSelectedServer()}
+          setSelectedServer={this.setSelectedServer}
+          setServerVariableValue={this.setServerVariableValue}
+          getServerVariable={this.getServerVariable}
+          getEffectiveServerValue={this.getEffectiveServerValue}
+          />
+      </div>
+    </div>
+  }
+}
diff --git a/src/core/plugins/oas3/components/servers.jsx b/src/core/plugins/oas3/components/servers.jsx
index 75b528f5..d6ed4a63 100644
--- a/src/core/plugins/oas3/components/servers.jsx
+++ b/src/core/plugins/oas3/components/servers.jsx
@@ -15,7 +15,11 @@ export default class Servers extends React.Component {
   }
 
   componentDidMount() {
-    let { servers } = this.props
+    let { servers, currentServer } = this.props
+
+    if(currentServer) {
+      return
+    }
 
     //fire 'change' event to set default 'value' of select
     this.setServer(servers.first().get("url"))
@@ -93,9 +97,8 @@ export default class Servers extends React.Component {
     let shouldShowVariableUI = currentServerVariableDefs.size !== 0
 
     return (
-      <div>
+      <div className="servers">
         <label htmlFor="servers">
-          <span className="servers-title">Servers</span>
           <select onChange={ this.onServerChange }>
             { servers.valueSeq().map(
               ( server ) =>
@@ -109,13 +112,14 @@ export default class Servers extends React.Component {
         </label>
         { shouldShowVariableUI ?
           <div>
-          <h4>Server variables</h4>
+
             <div className={"computed-url"}>
               Computed URL:
               <code>
                 {getEffectiveServerValue(currentServer)}
               </code>
             </div>
+            <h4>Server variables</h4>
             <table>
               <tbody>
                 {
diff --git a/src/core/plugins/oas3/reducers.js b/src/core/plugins/oas3/reducers.js
index 8590284d..871aff89 100644
--- a/src/core/plugins/oas3/reducers.js
+++ b/src/core/plugins/oas3/reducers.js
@@ -7,8 +7,9 @@ import {
 } from "./actions"
 
 export default {
-  [UPDATE_SELECTED_SERVER]: (state, { payload: selectedServerUrl } ) =>{
-    return state.setIn( [ "selectedServer" ], selectedServerUrl)
+  [UPDATE_SELECTED_SERVER]: (state, { payload: { selectedServerUrl, namespace } } ) =>{
+    const path = namespace ? [ namespace, "selectedServer"] : [ "selectedServer"]
+    return state.setIn( path, selectedServerUrl)
   },
   [UPDATE_REQUEST_BODY_VALUE]: (state, { payload: { value, pathMethod } } ) =>{
     let [path, method] = pathMethod
@@ -21,7 +22,8 @@ export default {
   [UPDATE_RESPONSE_CONTENT_TYPE]: (state, { payload: { value, path, method } } ) =>{
     return state.setIn( [ "requestData", path, method, "responseContentType" ], value)
   },
-  [UPDATE_SERVER_VARIABLE_VALUE]: (state, { payload: { server, key, val } } ) =>{
-    return state.setIn( [ "serverVariableValues", server, key ], val)
+  [UPDATE_SERVER_VARIABLE_VALUE]: (state, { payload: { server, namespace, key, val } } ) =>{
+    const path = namespace ? [ namespace, "serverVariableValues", server, key ] : [ "serverVariableValues", server, key ]
+    return state.setIn(path, val)
   },
 }
diff --git a/src/core/plugins/oas3/selectors.js b/src/core/plugins/oas3/selectors.js
index 86fc617f..c65a6882 100644
--- a/src/core/plugins/oas3/selectors.js
+++ b/src/core/plugins/oas3/selectors.js
@@ -15,8 +15,9 @@ function onlyOAS3(selector) {
   }
 }
 
-export const selectedServer = onlyOAS3(state => {
-    return state.getIn(["selectedServer"]) || ""
+export const selectedServer = onlyOAS3((state, namespace) => {
+    const path = namespace ? [namespace, "selectedServer"] : ["selectedServer"]
+    return state.getIn(path) || ""
   }
 )
 
@@ -35,19 +36,68 @@ export const responseContentType = onlyOAS3((state, path, method) => {
   }
 )
 
-export const serverVariableValue = onlyOAS3((state, server, key) => {
-    return state.getIn(["serverVariableValues", server, key]) || null
+export const serverVariableValue = onlyOAS3((state, locationData, key) => {
+    let path
+
+    // locationData may take one of two forms, for backwards compatibility
+    // Object: ({server, namespace?}) or String:(server)
+    if(typeof locationData !== "string") {
+      const { server, namespace } = locationData
+      if(namespace) {
+        path = [namespace, "serverVariableValues", server, key]
+      } else {
+        path = ["serverVariableValues", server, key]
+      }
+    } else {
+      const server = locationData
+      path = ["serverVariableValues", server, key]
+    }
+
+    return state.getIn(path) || null
   }
 )
 
-export const serverVariables = onlyOAS3((state, server) => {
-    return state.getIn(["serverVariableValues", server]) || OrderedMap()
+export const serverVariables = onlyOAS3((state, locationData) => {
+    let path
+
+    // locationData may take one of two forms, for backwards compatibility
+    // Object: ({server, namespace?}) or String:(server)
+    if(typeof locationData !== "string") {
+      const { server, namespace } = locationData
+      if(namespace) {
+        path = [namespace, "serverVariableValues", server]
+      } else {
+        path = ["serverVariableValues", server]
+      }
+    } else {
+      const server = locationData
+      path = ["serverVariableValues", server]
+    }
+
+    return state.getIn(path) || OrderedMap()
   }
 )
 
-export const serverEffectiveValue = onlyOAS3((state, server) => {
-    let varValues = state.getIn(["serverVariableValues", server]) || OrderedMap()
-    let str = server
+export const serverEffectiveValue = onlyOAS3((state, locationData) => {
+    var varValues, serverValue
+
+    // locationData may take one of two forms, for backwards compatibility
+    // Object: ({server, namespace?}) or String:(server)
+    if(typeof locationData !== "string") {
+      const { server, namespace } = locationData
+      serverValue = server
+      if(namespace) {
+        varValues = state.getIn([namespace, "serverVariableValues", serverValue])
+      } else {
+        varValues = state.getIn(["serverVariableValues", serverValue])
+      }
+    } else {
+      serverValue = locationData
+      varValues = state.getIn(["serverVariableValues", serverValue])
+    }
+
+    varValues = varValues || OrderedMap()
+    let str = serverValue
 
     varValues.map((val, key) => {
       str = str.replace(new RegExp(`{${key}}`, "g"), val)
diff --git a/src/core/plugins/spec/actions.js b/src/core/plugins/spec/actions.js
index 75c2a6b4..5e6f51fc 100644
--- a/src/core/plugins/spec/actions.js
+++ b/src/core/plugins/spec/actions.js
@@ -228,9 +228,18 @@ export const executeRequest = (req) =>
     }
 
     if(specSelectors.isOAS3()) {
-      // OAS3 request feature support
-      req.server = oas3Selectors.selectedServer()
-      req.serverVariables = oas3Selectors.serverVariables(req.server).toJS()
+      const namespace = `${pathName}:${method}`
+
+      req.server = oas3Selectors.selectedServer(namespace) || oas3Selectors.selectedServer()
+
+      const namespaceVariables = oas3Selectors.serverVariables({
+        server: req.server,
+        namespace
+      }).toJS()
+      const globalVariables = oas3Selectors.serverVariables({ server: req.server }).toJS()
+
+      req.serverVariables = Object.keys(namespaceVariables).length ? namespaceVariables : globalVariables
+
       req.requestContentType = oas3Selectors.requestContentType(pathName, method)
       req.responseContentType = oas3Selectors.responseContentType(pathName, method) || "*/*"
       const requestBody = oas3Selectors.requestBodyValue(pathName, method)
diff --git a/src/style/_layout.scss b/src/style/_layout.scss
index 0427b276..1d399f76 100644
--- a/src/style/_layout.scss
+++ b/src/style/_layout.scss
@@ -650,78 +650,6 @@
     }
 }
 
-.server-container
-{
-    margin: 0 0 20px 0;
-    padding: 30px 0;
-
-    background: $server-container-background-color;
-    box-shadow: 0 1px 2px 0 rgba($server-container-box-shadow-color,.15);
-
-    .computed-url {
-      margin: 2em 0;
-
-      code {
-        color: $server-container-computed-url-code-font-color;
-        display: inline-block;
-        padding: 4px;
-        font-size: 16px;
-        margin: 0 1em;
-        font-style: italic;
-      }
-    }
-
-    .servers
-    {
-        display: flex;
-        align-items: center;
-
-        .servers-title {
-          margin-right: 1em;
-        }
-
-         > label
-        {
-            font-size: 12px;
-
-            display: flex;
-            flex-direction: column;
-
-            margin: -20px 15px 0 0;
-
-            @include text_headline();
-
-            select
-            {
-                min-width: 130px;
-            }
-        }
-
-        table {
-            tr {
-                width: 30em;
-            }
-            td {
-                display: inline-block;
-                max-width: 15em;
-                vertical-align: middle;
-                padding-top: 10px;
-                padding-bottom: 10px;
-
-                &:first-of-type {
-                  padding-right: 2em;
-                }
-
-                input {
-                    width: 100%;
-                    height: 100%;
-                }
-            }
-        }
-    }
-}
-
-
 .loading-container
 {
     padding: 40px 0 60px;
diff --git a/src/style/_servers.scss b/src/style/_servers.scss
new file mode 100644
index 00000000..bf3ae39a
--- /dev/null
+++ b/src/style/_servers.scss
@@ -0,0 +1,74 @@
+.servers
+{
+     > label
+    {
+        font-size: 12px;
+
+        margin: -20px 15px 0 0;
+
+        @include text_headline();
+
+        select
+        {
+            min-width: 130px;
+        }
+    }
+
+    h4.message {
+      padding-bottom: 2em;
+    }
+
+    table {
+        tr {
+            width: 30em;
+        }
+        td {
+            display: inline-block;
+            max-width: 15em;
+            vertical-align: middle;
+            padding-top: 10px;
+            padding-bottom: 10px;
+
+            &:first-of-type {
+              padding-right: 2em;
+            }
+
+            input {
+                width: 100%;
+                height: 100%;
+            }
+        }
+    }
+
+    .computed-url {
+      margin: 2em 0;
+
+      code {
+        display: inline-block;
+        padding: 4px;
+        font-size: 16px;
+        margin: 0 1em;
+      }
+    }
+}
+
+
+.global-server-container
+{
+    margin: 0 0 20px 0;
+    padding: 30px 0;
+
+    background: $server-container-background-color;
+    box-shadow: 0 1px 2px 0 rgba($server-container-box-shadow-color,.15);
+
+    .servers-title {
+      line-height: 2em;
+      font-weight: bold;
+    }
+}
+
+.operation-servers {
+  h4.message {
+    margin-bottom: 2em;
+  }
+}
diff --git a/src/style/main.scss b/src/style/main.scss
index edc7e4f3..23bf2585 100644
--- a/src/style/main.scss
+++ b/src/style/main.scss
@@ -9,6 +9,7 @@
     @import 'form';
     @import 'modal';
     @import 'models';
+    @import 'servers';
     @import 'table';
     @import 'topbar';
     @import 'information';
diff --git a/test/core/plugins/oas3/state-integration.js b/test/core/plugins/oas3/state-integration.js
new file mode 100644
index 00000000..6ce69da5
--- /dev/null
+++ b/test/core/plugins/oas3/state-integration.js
@@ -0,0 +1,359 @@
+import expect from "expect"
+import { fromJS, OrderedMap } from "immutable"
+
+import {
+  selectedServer,
+  serverVariableValue,
+  serverVariables,
+  serverEffectiveValue
+} from "corePlugins/oas3/selectors"
+
+import reducers from "corePlugins/oas3/reducers"
+
+import {
+  setSelectedServer,
+  setServerVariableValue,
+} from "corePlugins/oas3/actions"
+
+describe("OAS3 plugin - state", function() {
+  describe("action + reducer + selector integration", function() {
+    describe("selectedServer", function() {
+      it("should set and get a global selectedServer", function() {
+        const state = new OrderedMap()
+        const system = {
+          // needed to handle `onlyOAS3` wrapper
+          getSystem() {
+            return {
+              specSelectors: {
+                specJson: () => {
+                  return fromJS({ openapi: "3.0.0" })
+                }
+              }
+            }
+          }
+        }
+
+        // Create the action
+        const action = setSelectedServer("http://google.com")
+
+        // Collect the new state
+        const newState = reducers["oas3_set_servers"](state, action)
+
+        // Get the value with the selector
+        const res = selectedServer(newState)(system)
+
+        expect(res).toEqual("http://google.com")
+      })
+
+      it("should set and get a namespaced selectedServer", function() {
+        const state = fromJS({
+          selectedServer: "http://yahoo.com"
+        })
+        const system = {
+          // needed to handle `onlyOAS3` wrapper
+          getSystem() {
+            return {
+              specSelectors: {
+                specJson: () => {
+                  return fromJS({ openapi: "3.0.0" })
+                }
+              }
+            }
+          }
+        }
+
+        // Create the action
+        const action = setSelectedServer("http://google.com", "myOperation")
+
+        // Collect the new state
+        const newState = reducers["oas3_set_servers"](state, action)
+
+        // Get the value with the selector
+        const res = selectedServer(newState, "myOperation")(system)
+
+        // Get the global selected server
+        const globalRes = selectedServer(newState)(system)
+
+        expect(res).toEqual("http://google.com")
+        expect(globalRes).toEqual("http://yahoo.com")
+      })
+    })
+
+    describe("serverVariableValue", function() {
+      it("should set and get a global serverVariableValue", function() {
+        const state = new OrderedMap()
+        const system = {
+          // needed to handle `onlyOAS3` wrapper
+          getSystem() {
+            return {
+              specSelectors: {
+                specJson: () => {
+                  return fromJS({ openapi: "3.0.0" })
+                }
+              }
+            }
+          }
+        }
+
+        // Create the action
+        const action = setServerVariableValue({
+          server: "google.com",
+          key: "foo",
+          val: "bar"
+        })
+
+        // Collect the new state
+        const newState = reducers["oas3_set_server_variable_value"](state, action)
+
+        // Get the value with the selector
+        const res = serverVariableValue(newState, "google.com", "foo")(system)
+
+        expect(res).toEqual("bar")
+      })
+      it("should set and get a namespaced serverVariableValue", function() {
+        const state = fromJS({
+          serverVariableValues: {
+            "google.com": {
+              foo: "123"
+            }
+          }
+        })
+        const system = {
+          // needed to handle `onlyOAS3` wrapper
+          getSystem() {
+            return {
+              specSelectors: {
+                specJson: () => {
+                  return fromJS({ openapi: "3.0.0" })
+                }
+              }
+            }
+          }
+        }
+
+        // Create the action
+        const action = setServerVariableValue({
+          namespace: "myOperation",
+          server: "google.com",
+          key: "foo",
+          val: "bar"
+        })
+
+        // Collect the new state
+        const newState = reducers["oas3_set_server_variable_value"](state, action)
+
+        // Get the value with the selector
+        const res = serverVariableValue(newState, {
+          namespace: "myOperation",
+          server: "google.com"
+        }, "foo")(system)
+
+        // Get the global value, to cross-check
+        const globalRes = serverVariableValue(newState, {
+          server: "google.com"
+        }, "foo")(system)
+
+        expect(res).toEqual("bar")
+        expect(globalRes).toEqual("123")
+      })
+    })
+
+    describe("serverVariables", function() {
+      it("should set and get global serverVariables", function() {
+        const state = new OrderedMap()
+        const system = {
+          // needed to handle `onlyOAS3` wrapper
+          getSystem() {
+            return {
+              specSelectors: {
+                specJson: () => {
+                  return fromJS({ openapi: "3.0.0" })
+                }
+              }
+            }
+          }
+        }
+
+        // Create the action
+        const action = setServerVariableValue({
+          server: "google.com",
+          key: "foo",
+          val: "bar"
+        })
+
+        // Collect the new state
+        const newState = reducers["oas3_set_server_variable_value"](state, action)
+
+        // Get the value with the selector
+        const res = serverVariables(newState, "google.com", "foo")(system)
+
+        expect(res.toJS()).toEqual({
+          foo: "bar"
+        })
+      })
+
+      it("should set and get namespaced serverVariables", function() {
+        const state = fromJS({
+          serverVariableValues: {
+            "google.com": {
+              foo: "123"
+            }
+          }
+        })
+
+        const system = {
+          // needed to handle `onlyOAS3` wrapper
+          getSystem() {
+            return {
+              specSelectors: {
+                specJson: () => {
+                  return fromJS({ openapi: "3.0.0" })
+                }
+              }
+            }
+          }
+        }
+
+        // Create the action
+        const action = setServerVariableValue({
+          namespace: "myOperation",
+          server: "google.com",
+          key: "foo",
+          val: "bar"
+        })
+
+        // Collect the new state
+        const newState = reducers["oas3_set_server_variable_value"](state, action)
+
+        // Get the value with the selector
+        const res = serverVariables(newState, {
+          namespace: "myOperation",
+          server: "google.com"
+        }, "foo")(system)
+
+        // Get the global value, to cross-check
+        const globalRes = serverVariables(newState, {
+          server: "google.com"
+        }, "foo")(system)
+
+        expect(res.toJS()).toEqual({
+          foo: "bar"
+        })
+
+        expect(globalRes.toJS()).toEqual({
+          foo: "123"
+        })
+      })
+    })
+    describe("serverEffectiveValue", function() {
+        it("should set variable values and compute a URL for a namespaced server", function() {
+          const state = fromJS({
+            serverVariableValues: {
+              "google.com/{foo}": {
+                foo: "123"
+              }
+            }
+          })
+
+          const system = {
+            // needed to handle `onlyOAS3` wrapper
+            getSystem() {
+              return {
+                specSelectors: {
+                  specJson: () => {
+                    return fromJS({ openapi: "3.0.0" })
+                  }
+                }
+              }
+            }
+          }
+
+          // Create the action
+          const action = setServerVariableValue({
+            namespace: "myOperation",
+            server: "google.com/{foo}",
+            key: "foo",
+            val: "bar"
+          })
+
+          // Collect the new state
+          const newState = reducers["oas3_set_server_variable_value"](state, action)
+
+          // Get the value with the selector
+          const res = serverEffectiveValue(newState, {
+            namespace: "myOperation",
+            server: "google.com/{foo}"
+          })(system)
+
+          // Get the global value, to cross-check
+          const globalRes = serverEffectiveValue(newState, {
+            server: "google.com/{foo}"
+          })(system)
+
+          expect(res).toEqual("google.com/bar")
+
+          expect(globalRes).toEqual("google.com/123")
+        })
+      })
+
+  })
+  describe("selectors", function() {
+    describe("serverEffectiveValue", function() {
+      it("should compute global serverEffectiveValues", function() {
+        const state = fromJS({
+          serverVariableValues: {
+            "google.com/{foo}/{bar}": {
+              foo: "123",
+              bar: "456"
+            }
+          }
+        })
+        const system = {
+          // needed to handle `onlyOAS3` wrapper
+          getSystem() {
+            return {
+              specSelectors: {
+                specJson: () => {
+                  return fromJS({ openapi: "3.0.0" })
+                }
+              }
+            }
+          }
+        }
+
+        // Get the value with the selector
+        const res = serverEffectiveValue(state, "google.com/{foo}/{bar}")(system)
+
+        expect(res).toEqual("google.com/123/456")
+      })
+
+      it("should handle multiple variable instances", function() {
+        const state = fromJS({
+          serverVariableValues: {
+            "google.com/{foo}/{foo}/{bar}": {
+              foo: "123",
+              bar: "456"
+            }
+          }
+        })
+        const system = {
+          // needed to handle `onlyOAS3` wrapper
+          getSystem() {
+            return {
+              specSelectors: {
+                specJson: () => {
+                  return fromJS({ openapi: "3.0.0" })
+                }
+              }
+            }
+          }
+        }
+
+        // Get the value with the selector
+        const res = serverEffectiveValue(state, "google.com/{foo}/{foo}/{bar}")(system)
+
+        expect(res).toEqual("google.com/123/123/456")
+      })
+    })
+  })
+})