diff --git a/src/app/compiler/compiler-helpers.js b/src/app/compiler/compiler-helpers.js
index a20ffa13b1..820e5c298f 100644
--- a/src/app/compiler/compiler-helpers.js
+++ b/src/app/compiler/compiler-helpers.js
@@ -1,5 +1,5 @@
 'use strict'
-import { canUseWorker } from './compiler-utils'
+import { canUseWorker, urlFromVersion } from './compiler-utils'
 import { Compiler } from 'remix-solidity'
 import CompilerAbstract from './compiler-abstract'
 
@@ -9,7 +9,7 @@ export const compile = async (compilationTargets, settings) => {
       const compiler = new Compiler(() => {})
       compiler.set('evmVersion', settings.evmVersion)
       compiler.set('optimize', settings.optimize)
-      compiler.loadVersion(canUseWorker(settings.version), settings.compilerUrl)
+      compiler.loadVersion(canUseWorker(settings.version), urlFromVersion(settings.version))
       compiler.event.register('compilationFinished', (success, compilationData, source) => {
         if (!success) return reject(compilationData)
         resolve(new CompilerAbstract(settings.version, compilationData, source))
diff --git a/src/app/compiler/compiler-sourceVerifier-fetchAndCompile.js b/src/app/compiler/compiler-sourceVerifier-fetchAndCompile.js
index 04956b5ac7..8da3dd9bb1 100644
--- a/src/app/compiler/compiler-sourceVerifier-fetchAndCompile.js
+++ b/src/app/compiler/compiler-sourceVerifier-fetchAndCompile.js
@@ -1,7 +1,6 @@
 const ethutil = require('ethereumjs-util')
 import * as packageJson from '../../../package.json'
 import { Plugin } from '@remixproject/engine'
-import { urlFromVersion } from './compiler-utils'
 import { compile } from './compiler-helpers'
 import globalRegistry from '../../global/registry'
 
@@ -109,7 +108,6 @@ export default class FetchAndCompile extends Plugin {
       languageName: data.metadata.language,
       evmVersion: data.metadata.settings.evmVersion,
       optimize: data.metadata.settings.optimizer.enabled,
-      compilerUrl: urlFromVersion(data.metadata.compiler.version)
     }
     try {
       setTimeout(_ => this.emit('compiling', settings), 0)
diff --git a/src/app/compiler/compiler-utils.js b/src/app/compiler/compiler-utils.js
index 25e6425f10..a36e25a83c 100644
--- a/src/app/compiler/compiler-utils.js
+++ b/src/app/compiler/compiler-utils.js
@@ -1,11 +1,15 @@
-// const semver = require('semver')
+ const semver = require('semver')
 /* global Worker */
 
-export const baseUrl = 'https://solc-bin.ethereum.org/wasm'
+export const baseURLBin = 'https://solc-bin.ethereum.org/bin'
+export const baseURLWasm = 'https://solc-bin.ethereum.org/wasm'
+
+export const pathToURL = []
 
 export function urlFromVersion (version) {
-  return `${baseUrl}/soljson-v${version}.js`
+  return `${pathToURL[version]}/${version}`
 }
+
 /**
  * Checks if the worker can be used to load a compiler.
  * checks a compiler whitelist, browser support and OS.
@@ -30,7 +34,14 @@ export function canUseWorker (selectedVersion) {
     default :
       isFromWhiteList = true
   } */
-  return browserSupportWorker()// && (!isChrome || (isChrome && isFromWhiteList))
+  const version = semver.coerce(selectedVersion)
+  const isNightly = selectedVersion.includes('nightly')
+  return browserSupportWorker() && 
+    (
+      semver.gt(version, '0.6.3') ||
+      semver.gt(version, '0.3.5') && !isNightly
+    )
+    // && (!isChrome || (isChrome && isFromWhiteList))
 }
 
 function browserSupportWorker () {
diff --git a/src/app/tabs/compileTab/compilerContainer.js b/src/app/tabs/compileTab/compilerContainer.js
index 960f5c8d16..e7ef28696d 100644
--- a/src/app/tabs/compileTab/compilerContainer.js
+++ b/src/app/tabs/compileTab/compilerContainer.js
@@ -6,7 +6,7 @@ const addTooltip = require('../../ui/tooltip')
 const semver = require('semver')
 const modalDialogCustom = require('../../ui/modal-dialog-custom')
 const css = require('../styles/compile-tab-styles')
-import { canUseWorker, baseUrl } from '../../compiler/compiler-utils'
+import { canUseWorker, baseURLBin, baseURLWasm, urlFromVersion, pathToURL } from '../../compiler/compiler-utils'
 
 class CompilerContainer {
 
@@ -25,7 +25,8 @@ class CompilerContainer {
       allversions: null,
       selectedVersion: null,
       defaultVersion: 'soljson-v0.6.6+commit.6c089d02.js', // this default version is defined: in makeMockCompiler (for browser test) and in package.json (downloadsolc_root) for the builtin compiler
-      baseurl: baseUrl
+      baseURLWasm: baseURLWasm,
+      baseURLBin: baseURLBin
     }
   }
 
@@ -383,7 +384,7 @@ class CompilerContainer {
       if (this.data.selectedVersion.indexOf('soljson') !== 0 || helper.checkSpecialChars(this.data.selectedVersion)) {
         return console.log('loading ' + this.data.selectedVersion + ' not allowed')
       }
-      url = `${this.data.baseurl}/${this.data.selectedVersion}`
+      url = `${urlFromVersion(this.data.selectedVersion)}`
     }
 
     // Workers cannot load js on "file:"-URLs and we get a
@@ -413,25 +414,59 @@ class CompilerContainer {
     if (this._view.version) this._view.version.innerText = text
   }
 
+  // fetching both normal and wasm builds and creating an array [version, baseUrl]
   fetchAllVersion (callback) {
-    minixhr(`${this.data.baseurl}/list.json`, (json, event) => {
+    let allVersions, selectedVersion, allVersionsWasm, urls
+    // fetch normal builds
+    minixhr(`${this.data.baseURLBin}/list.json`, (json, event) => {
       // @TODO: optimise and cache results to improve app loading times #2461
-      var allversions, selectedVersion
       if (event.type !== 'error') {
         try {
           const data = JSON.parse(json)
-          allversions = data.builds.slice().reverse()
+          allVersions = data.builds.slice().reverse()
           selectedVersion = this.data.defaultVersion
           if (this.queryParams.get().version) selectedVersion = this.queryParams.get().version
+          // no fetching wasm builds
+          minixhr(`${this.data.baseURLWasm}/list.json`, (json, event) => {
+            // @TODO: optimise and cache results to improve app loading times #2461
+            if (event.type !== 'error') {
+              try {
+                const data = JSON.parse(json)
+                allVersionsWasm = data.builds.slice().reverse()
+                //selectedVersion = this.data.defaultVersion
+                if (this.queryParams.get().version) selectedVersion = this.queryParams.get().version
+                // rewriting all versions in allVersions which exist in allVersionsWasm
+                if (allVersionsWasm && allVersions)
+                allVersions.forEach((compiler, index) => {
+                  const rewritten = allVersionsWasm.findIndex(oldCompiler => { return oldCompiler.longVersion === compiler.longVersion })
+                  if (-1 !== rewritten) {
+                    allVersions[index] = allVersionsWasm[rewritten]
+                    pathToURL[compiler.path] = baseURLWasm
+                  } else {
+                    pathToURL[compiler.path] = baseURLBin
+                  }
+                })
+                callback(allVersions, selectedVersion)
+              } catch (e) {
+                addTooltip('Cannot load compiler version list. It might have been blocked by an advertisement blocker. Please try deactivating any of them from this page and reload.')
+              }
+            } else {
+              allVersionsWasm = [{ path: 'builtin', longVersion: 'latest local version' }]
+              selectedVersion = 'builtin'
+            }
+            //callback(allVersions, selectedVersion)
+          })
         } catch (e) {
           addTooltip('Cannot load compiler version list. It might have been blocked by an advertisement blocker. Please try deactivating any of them from this page and reload.')
         }
       } else {
-        allversions = [{ path: 'builtin', longVersion: 'latest local version' }]
+        allVersions = [{ path: 'builtin', longVersion: 'latest local version' }]
         selectedVersion = 'builtin'
       }
-      callback(allversions, selectedVersion)
+      //callback(allVersions, selectedVersion)
     })
+    
+    
   }
 
   scheduleCompilation () {
diff --git a/src/app/tabs/test-tab.js b/src/app/tabs/test-tab.js
index 2dfb270a9f..abc9986a1d 100644
--- a/src/app/tabs/test-tab.js
+++ b/src/app/tabs/test-tab.js
@@ -4,7 +4,7 @@ var tooltip = require('../ui/tooltip')
 var css = require('./styles/test-tab-styles')
 var remixTests = require('remix-tests')
 import { ViewPlugin } from '@remixproject/engine'
-import { canUseWorker, baseUrl } from '../compiler/compiler-utils'
+import { canUseWorker, urlFromVersion } from '../compiler/compiler-utils'
 
 const TestTabLogic = require('./testTab/testTab')
 
@@ -301,7 +301,7 @@ module.exports = class TestTab extends ViewPlugin {
       let runningTest = {}
       runningTest[path] = { content }
       const {currentVersion, evmVersion, optimize} = this.compileTab.getCurrentCompilerConfig()
-      const currentCompilerUrl = baseUrl + '/' + currentVersion
+      const currentCompilerUrl = urlFromVersion(currentVersion)
       const compilerConfig = {
         currentCompilerUrl,
         evmVersion,
@@ -327,7 +327,7 @@ module.exports = class TestTab extends ViewPlugin {
       const runningTest = {}
       runningTest[testFilePath] = { content }
       const {currentVersion, evmVersion, optimize} = this.compileTab.getCurrentCompilerConfig()
-      const currentCompilerUrl = baseUrl + '/' + currentVersion
+      const currentCompilerUrl = urlFromVersion(currentVersion)
       const compilerConfig = {
         currentCompilerUrl,
         evmVersion,
diff --git a/src/lib/helper.js b/src/lib/helper.js
index cda3bfe519..15f692fcc1 100644
--- a/src/lib/helper.js
+++ b/src/lib/helper.js
@@ -84,4 +84,3 @@ function find (args, query) {
   })
   return isMatch
 }
-