diff --git a/src/execute.js b/src/execute.js
index 49fd6b723..6fb256379 100644
--- a/src/execute.js
+++ b/src/execute.js
@@ -1,6 +1,7 @@
 import assign from 'lodash/assign'
 import getIn from 'lodash/get'
 import btoa from 'btoa'
+import url from 'url'
 import http, {mergeInQueryOrForm} from './http'
 import {getOperationRaw, idFromPathMethod} from './helpers'
 
@@ -54,13 +55,13 @@ export function execute({
 export function buildRequest({
   spec, operationId, parameters, securities, requestContentType,
   responseContentType, parameterBuilders, scheme,
-  requestInterceptor, responseInterceptor
+  requestInterceptor, responseInterceptor, contextUrl
 }) {
   parameterBuilders = parameterBuilders || PARAMETER_BUILDERS
-  
+
   // Base Template
   let req = {
-    url: baseUrl(spec, scheme),
+    url: baseUrl({spec, scheme, contextUrl}),
     headers: {
       // This breaks CORSs... removing this line... probably breaks oAuth. Need to address that
       // This also breaks tests
@@ -173,14 +174,16 @@ export function queryBuilder({req, value, parameter}) {
 }
 
 // Compose the baseUrl ( scheme + host + basePath )
-export function baseUrl(spec, scheme) {
+export function baseUrl({spec, scheme, contextUrl = ''}) {
   const {host, basePath, schemes = ['http']} = spec
 
+  const parsedUrl = url.parse(contextUrl)
+
   let applyScheme = ['http', 'https'].indexOf(scheme) > -1 ? scheme : schemes[0]
   applyScheme = applyScheme ? `${applyScheme}:` : ''
 
-  if (host || basePath) {
-    return `${applyScheme}//${host || ''}${basePath || ''}`
+  if (host || basePath || contextUrl) {
+    return `${applyScheme}//${host || parsedUrl.host || ''}${basePath || ''}`
   }
 
   return ''
diff --git a/test/execute.js b/test/execute.js
index 7a6fd37c1..fcffe5ba9 100644
--- a/test/execute.js
+++ b/test/execute.js
@@ -1,6 +1,6 @@
 import expect, {createSpy, spyOn} from 'expect'
 import xmock from 'xmock'
-import {execute, buildRequest, applySecurities, self as stubs} from '../src/execute'
+import {execute, buildRequest, baseUrl, applySecurities, self as stubs} from '../src/execute'
 
 // Supported shape...  { spec, operationId, parameters, securities, fetch }
 // One can use operationId or pathItem + method
@@ -1334,4 +1334,99 @@ describe('execute', () => {
       })
     })
   })
-})
\ No newline at end of file
+
+  describe('baseUrl', () => {
+    let contextUrl = "http://example.com:9090/hello/swagger.json"
+
+    it('should calculate a valid baseUrl given host, basePath, context, schemes', () => {
+      let res = baseUrl({
+        spec: {
+          schemes: ["https"],
+          host: "foo.com:8080",
+          basePath: "/bar"
+        },
+        contextUrl
+      })
+
+      expect(res).toEqual("https://foo.com:8080/bar")
+    })
+
+    it('should calculate a valid baseUrl given host, basePath, context', () => {
+      let res = baseUrl({
+        spec: {
+          host: "foo.com:8080",
+          basePath: "/bar"
+        },
+        contextUrl
+      })
+
+      expect(res).toEqual("http://foo.com:8080/bar")
+    })
+
+    it('should infer the host and port based on the contextUrl', () => {
+      let res = baseUrl({
+        spec: {
+          basePath: "/bar"
+        },
+        contextUrl
+      })
+
+      expect(res).toEqual("http://example.com:9090/bar")
+    })
+
+    it('should infer the entire url based on the contextUrl', () => {
+      let res = baseUrl({
+        spec: {},
+        contextUrl
+      })
+
+      expect(res).toEqual("http://example.com:9090")
+    })
+
+    it('should infer the host based on the contextUrl', () => {
+      let res = baseUrl({
+        spec: {
+          schemes: ['https'],
+          basePath: '/bar'
+        },
+        contextUrl
+      })
+
+      expect(res).toEqual("https://example.com:9090/bar")
+    })
+
+    it('should default to an empty basePath', () => {
+      let res = baseUrl({
+        spec: {
+          schemes: ['https'],
+          host: 'foo.com:8080'
+        },
+        contextUrl
+      })
+
+      expect(res).toEqual("https://foo.com:8080")
+    })
+
+    it('should default to the correct scheme based on the spec', () => {
+      let res = baseUrl({
+        spec: {
+          schemes: ['https']
+        },
+        contextUrl
+      })
+
+      expect(res).toEqual("https://example.com:9090")
+    })
+
+    it('should default to the correct scheme based on the spec', () => {
+      let res = baseUrl({
+        spec: {
+          host: 'foo.com:8080'
+        },
+        contextUrl
+      })
+
+      expect(res).toEqual("http://foo.com:8080")
+    })
+  })
+})