diff --git a/package-lock.json b/package-lock.json
index a6f9684..4db8a4f 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -2034,9 +2034,9 @@
       }
     },
     "@ffmpeg/core": {
-      "version": "0.6.0",
-      "resolved": "https://registry.npmjs.org/@ffmpeg/core/-/core-0.6.0.tgz",
-      "integrity": "sha512-5VNyabaCPZJEFmn92C5SIh2vFChL2l9OVGut1hmst8IPuChZahF6yniFjEdF2Ri8ZZFKXTAQrPh3WfpVaEPK9A=="
+      "version": "0.7.0",
+      "resolved": "https://registry.npmjs.org/@ffmpeg/core/-/core-0.7.0.tgz",
+      "integrity": "sha512-ulDKwckLF4NrNIn98sYe8KCzKM9GfIfc9kR2Mel4pA8URQ9GEr2tGDMST5xW63Usnr6ybZCZKgwiDkAHK7VWCQ=="
     },
     "@hapi/address": {
       "version": "2.1.2",
diff --git a/package.json b/package.json
index 745aece..c05d929 100644
--- a/package.json
+++ b/package.json
@@ -14,13 +14,13 @@
     "wait": "rimraf dist && wait-on http://localhost:3000/dist/ffmpeg.dev.js",
     "test": "npm-run-all -p -r start test:all",
     "test:all": "npm-run-all wait test:browser:ffmpeg test:node:all",
-    "test:node": "NODE_OPTIONS=--experimental-worker nyc mocha --exit --bail --require ./scripts/test-helper.js",
+    "test:node": "node --experimental-wasm-threads --experimental-wasm-bulk-memory node_modules/.bin/_mocha --exit --bail --require ./scripts/test-helper.js",
     "test:node:all": "npm run test:node -- ./tests/*.test.js",
-    "test:browser": "mocha-headless-chrome -a incognito -a no-sandbox -a disable-setuid-sandbox -a disable-logging -t 300000",
+    "test:browser": "mocha-headless-chrome -a allow-file-access-from-files -a incognito -a no-sandbox -a disable-setuid-sandbox -a disable-logging -t 300000",
     "test:browser:ffmpeg": "npm run test:browser -- -f ./tests/ffmpeg.test.html"
   },
   "browser": {
-    "./src/worker/node/index.js": "./src/worker/browser/index.js"
+    "./src/node/index.js": "./src/browser/index.js"
   },
   "repository": {
     "type": "git",
@@ -37,11 +37,11 @@
     "url": "https://github.com/ffmpegjs/ffmpeg.js/issues"
   },
   "engines": {
-    "node": ">=10.5.0"
+    "node": ">=12.16.1"
   },
   "homepage": "https://github.com/ffmpegjs/ffmpeg.js#readme",
   "dependencies": {
-    "@ffmpeg/core": "^0.6.0",
+    "@ffmpeg/core": "^0.7.0",
     "idb": "^4.0.5",
     "is-electron": "^2.2.0",
     "is-url": "^1.2.4",
diff --git a/scripts/webpack.config.dev.js b/scripts/webpack.config.dev.js
index 25299a7..cbe7469 100644
--- a/scripts/webpack.config.dev.js
+++ b/scripts/webpack.config.dev.js
@@ -32,8 +32,4 @@ module.exports = [
     library: 'FFmpeg',
     libraryTarget: 'umd',
   }),
-  genConfig({
-    entry: path.resolve(__dirname, '..', 'src', 'worker-script', 'browser', 'index.js'),
-    filename: 'worker.dev.js',
-  }),
 ];
diff --git a/scripts/webpack.config.prod.js b/scripts/webpack.config.prod.js
index 74ef83d..8f1bac3 100644
--- a/scripts/webpack.config.prod.js
+++ b/scripts/webpack.config.prod.js
@@ -23,8 +23,4 @@ module.exports = [
     library: 'FFmpeg',
     libraryTarget: 'umd',
   }),
-  genConfig({
-    entry: path.resolve(__dirname, '..', 'src', 'worker-script', 'browser', 'index.js'),
-    filename: 'worker.min.js',
-  }),
 ];
diff --git a/src/browser/defaultOptions.js b/src/browser/defaultOptions.js
new file mode 100644
index 0000000..1d9db84
--- /dev/null
+++ b/src/browser/defaultOptions.js
@@ -0,0 +1,13 @@
+const resolveURL = require('resolve-url');
+const { dependencies } = require('../../package.json');
+const defaultOptions = require('../constants/defaultOptions');
+
+/*
+ * Default options for browser worker
+ */
+module.exports = {
+  ...defaultOptions,
+  corePath: (typeof process !== 'undefined' && process.env.FFMPEG_ENV === 'development')
+    ? resolveURL('/node_modules/@ffmpeg/core/ffmpeg-core.js')
+    : `https://unpkg.com/@ffmpeg/core@v${dependencies['@ffmpeg/core'].substring(1)}/ffmpeg-core.js`,
+};
diff --git a/src/worker/browser/fetchFile.js b/src/browser/fetchFile.js
similarity index 100%
rename from src/worker/browser/fetchFile.js
rename to src/browser/fetchFile.js
diff --git a/src/browser/getModule.js b/src/browser/getModule.js
new file mode 100644
index 0000000..7a87c6c
--- /dev/null
+++ b/src/browser/getModule.js
@@ -0,0 +1,23 @@
+const { log } = require('../utils/log');
+
+module.exports = ({ corePath }) => new Promise((resolve) => {
+  if (typeof window.Module === 'undefined') {
+    log('info', `download ffmpeg-core script (~25 MB) from ${corePath}`);
+    const script = document.createElement('script');
+    const eventHandler = () => {
+      script.removeEventListener('load', eventHandler);
+      log('info', 'initialize ffmpeg-core');
+      window.Module.onRuntimeInitialized = () => {
+        log('info', 'ffmpeg-core initialized');
+        resolve(window.Module);
+      };
+    };
+    script.src = corePath;
+    script.type = 'text/javascript';
+    script.addEventListener('load', eventHandler);
+    document.getElementsByTagName('head')[0].appendChild(script);
+  } else {
+    log('info', 'ffmpeg-core is loaded already');
+    resolve(window.Module);
+  }
+});
diff --git a/src/worker/node/index.js b/src/browser/index.js
similarity index 56%
rename from src/worker/node/index.js
rename to src/browser/index.js
index 997cb10..85ade1f 100644
--- a/src/worker/node/index.js
+++ b/src/browser/index.js
@@ -1,11 +1,9 @@
 const defaultOptions = require('./defaultOptions');
-const spawnWorker = require('./spawnWorker');
-const onMessage = require('./onMessage');
+const getModule = require('./getModule');
 const fetchFile = require('./fetchFile');
 
 module.exports = {
   defaultOptions,
-  spawnWorker,
-  onMessage,
+  getModule,
   fetchFile,
 };
diff --git a/src/worker-script/constants/defaultArgs.js b/src/constants/defaultArgs.js
similarity index 72%
rename from src/worker-script/constants/defaultArgs.js
rename to src/constants/defaultArgs.js
index 55aae4f..196b8e0 100755
--- a/src/worker-script/constants/defaultArgs.js
+++ b/src/constants/defaultArgs.js
@@ -1,4 +1,5 @@
 module.exports = [
   './ffmpeg', // args[0] is always binary path
   '-nostdin', // Disable interaction mode
+  '-hide_banner', // Not to output banner
 ];
diff --git a/src/constants/defaultOptions.js b/src/constants/defaultOptions.js
index 6955b45..f1732fe 100644
--- a/src/constants/defaultOptions.js
+++ b/src/constants/defaultOptions.js
@@ -1,4 +1,5 @@
 module.exports = {
+  log: false,
   logger: () => {},
   progress: () => {},
 };
diff --git a/src/createFFmpeg.js b/src/createFFmpeg.js
new file mode 100644
index 0000000..35f0b80
--- /dev/null
+++ b/src/createFFmpeg.js
@@ -0,0 +1,130 @@
+const defaultArgs = require('./constants/defaultArgs');
+const { setLogging, log } = require('./utils/log');
+const resolvePaths = require('./utils/resolvePaths');
+const parseProgress = require('./utils/parseProgress');
+const stringList2pointer = require('./utils/stringList2pointer');
+const {
+  defaultOptions,
+  getModule,
+  fetchFile,
+} = require('./node');
+
+const NO_LOAD = Error('FFmpeg.js is not ready, make sure you have completed load().');
+const NO_MULTIPLE_RUN = Error('FFmpeg.js can only run one command at a time');
+let Module = null;
+let ffmpeg = null;
+
+module.exports = (_options = {}) => {
+  let runResolve = null;
+  let running = false;
+  const {
+    log: logging,
+    logger,
+    progress,
+    ...options
+  } = resolvePaths({
+    ...defaultOptions,
+    ..._options,
+  });
+  const detectCompletion = ({ message, type }) => {
+    if (type === 'ffmpeg-stdout'
+      && message === 'FFMPEG_END'
+      && runResolve !== null) {
+      runResolve();
+      runResolve = null;
+      running = false;
+    }
+  };
+
+  setLogging(logging);
+
+  const load = async () => {
+    if (Module === null) {
+      log('info', 'load ffmpeg-core');
+      Module = await getModule(options);
+      Module.setLogger((_log) => {
+        detectCompletion(_log);
+        parseProgress(_log, progress);
+        logger(_log);
+        log(_log.type, _log.message);
+      });
+      if (ffmpeg === null) {
+        ffmpeg = Module.cwrap('proxy_main', 'number', ['number', 'number']);
+      }
+      log('info', 'ffmpeg-core loaded');
+    }
+  };
+
+  const FS = (method, args) => {
+    if (Module === null) {
+      throw NO_LOAD;
+    } else {
+      log('info', `FS.${method} ${args[0]}`);
+      return Module.FS[method](...args);
+    }
+  };
+
+  const write = async (path, data) => (
+    FS('writeFile', [path, await fetchFile(data)])
+  );
+
+  const writeText = (path, text) => (
+    FS('writeFile', [path, text])
+  );
+
+  const read = (path) => (
+    FS('readFile', [path])
+  );
+
+  const remove = (path) => (
+    FS('unlink', [path])
+  );
+
+  const ls = (path) => (
+    FS('readir', [path])
+  );
+
+  const run = (_args) => {
+    if (ffmpeg === null) {
+      throw NO_LOAD;
+    } else if (running) {
+      throw NO_MULTIPLE_RUN;
+    } else {
+      running = true;
+      return new Promise((resolve) => {
+        const args = [...defaultArgs, ..._args.trim().split(' ')].filter((s) => s.length !== 0);
+        log('info', `ffmpeg command: ${args.join(' ')}`);
+        runResolve = resolve;
+        ffmpeg(args.length, stringList2pointer(Module, args));
+      });
+    }
+  };
+
+  const transcode = (input, output, opts = '') => (
+    run(`-i ${input} ${opts} ${output}`)
+  );
+
+  const trim = (input, output, from, to, opts = '') => (
+    run(`-i ${input} -ss ${from} -to ${to} ${opts} ${output}`)
+  );
+
+  const concatDemuxer = (input, output, opts = '') => {
+    const text = input.reduce((acc, path) => `${acc}\nfile ${path}`, '');
+    writeText('concat_list.txt', text);
+    return run(`-f concat -safe 0 -i concat_list.txt ${opts} ${output}`);
+  };
+
+  return {
+    load,
+    FS,
+    write,
+    writeText,
+    read,
+    remove,
+    ls,
+    run,
+    transcode,
+    trim,
+    concatDemuxer,
+  };
+};
diff --git a/src/createJob.js b/src/createJob.js
deleted file mode 100644
index f90364d..0000000
--- a/src/createJob.js
+++ /dev/null
@@ -1,21 +0,0 @@
-const getId = require('./utils/getId');
-
-let jobCounter = 0;
-
-module.exports = ({
-  id: _id,
-  action,
-  payload = {},
-}) => {
-  let id = _id;
-  if (typeof id === 'undefined') {
-    id = getId('Job', jobCounter);
-    jobCounter += 1;
-  }
-
-  return {
-    id,
-    action,
-    payload,
-  };
-};
diff --git a/src/createWorker.js b/src/createWorker.js
deleted file mode 100644
index dcd25ee..0000000
--- a/src/createWorker.js
+++ /dev/null
@@ -1,217 +0,0 @@
-const createJob = require('./createJob');
-const { log } = require('./utils/log');
-const getId = require('./utils/getId');
-const parseProgress = require('./utils/parseProgress');
-const resolvePaths = require('./utils/resolvePaths');
-const getTransferables = require('./utils/getTransferables');
-const {
-  defaultOptions,
-  spawnWorker,
-  onMessage,
-  fetchFile,
-} = require('./worker/node');
-
-let workerCounter = 0;
-
-module.exports = (_options = {}) => {
-  const id = getId('Worker', workerCounter);
-  const {
-    logger,
-    progress,
-    ...options
-  } = resolvePaths({
-    ...defaultOptions,
-    ..._options,
-  });
-  const resolves = {};
-  const rejects = {};
-  let worker = spawnWorker(options);
-
-  workerCounter += 1;
-
-  const setResolve = (action, res) => {
-    resolves[action] = res;
-  };
-
-  const setReject = (action, rej) => {
-    rejects[action] = rej;
-  };
-
-  const startJob = ({ id: jobId, action, payload }) => (
-    new Promise((resolve, reject) => {
-      const packet = {
-        workerId: id,
-        jobId,
-        action,
-        payload,
-      };
-      log(`[${id}]: Start ${jobId}, action=${action}`);
-      setResolve(action, resolve);
-      setReject(action, reject);
-      /*
-       * By using Transferable in postMessage, we are able
-       * to send large files to worker
-       * @ref: https://github.com/ffmpegjs/ffmpeg.js/issues/8#issuecomment-572230128
-       */
-      worker.postMessage(packet, getTransferables(packet));
-    })
-  );
-
-  const load = (jobId) => (
-    startJob(createJob({
-      id: jobId, action: 'load', payload: { options },
-    }))
-  );
-
-  const write = async (path, data, jobId) => (
-    startJob(createJob({
-      id: jobId,
-      action: 'FS',
-      payload: {
-        method: 'writeFile',
-        args: [path, await fetchFile(data)],
-      },
-    }))
-  );
-
-  const writeText = (path, text, jobId) => (
-    startJob(createJob({
-      id: jobId,
-      action: 'FS',
-      payload: {
-        method: 'writeFile',
-        args: [path, text],
-      },
-    }))
-  );
-
-  const read = (path, jobId) => (
-    startJob(createJob({
-      id: jobId,
-      action: 'FS',
-      payload: {
-        method: 'readFile',
-        args: [path],
-      },
-    }))
-  );
-
-  const remove = (path, jobId) => (
-    startJob(createJob({
-      id: jobId,
-      action: 'FS',
-      payload: {
-        method: 'unlink',
-        args: [path],
-      },
-    }))
-  );
-
-  const run = (args, jobId) => (
-    startJob(createJob({
-      id: jobId,
-      action: 'run',
-      payload: {
-        args,
-      },
-    }))
-  );
-
-  const ls = (path, jobId) => (
-    startJob(createJob({
-      id: jobId,
-      action: 'FS',
-      payload: {
-        method: 'readdir',
-        args: [path],
-      },
-    }))
-  );
-
-  const transcode = (input, output, opts = '', jobId) => (
-    run(
-      `-i ${input} ${opts} ${output}`,
-      jobId,
-    )
-  );
-
-  const trim = (input, output, from, to, opts = '', jobId) => (
-    run(
-      `-i ${input} -ss ${from} -to ${to} ${opts} ${output}`,
-      jobId,
-    )
-  );
-
-  const concatDemuxer = async (input, output, opts = '', jobId) => {
-    const text = input.reduce((acc, path) => `${acc}\nfile ${path}`, '');
-    await writeText('concat_list.txt', text);
-    return run(`-f concat -safe 0 -i concat_list.txt ${opts} ${output}`, jobId);
-  };
-
-  const terminate = async () => {
-    if (worker !== null) {
-      /*
-      await startJob(createJob({
-        id: jobId,
-        action: 'terminate',
-      }));
-      */
-      worker.terminate();
-      worker = null;
-    }
-    return Promise.resolve();
-  };
-
-  onMessage(worker, ({
-    workerId, jobId, action, status, payload,
-  }) => {
-    if (status === 'resolve') {
-      const { message, data } = payload;
-      log(`[${workerId}]: Complete ${jobId}`);
-      resolves[action]({
-        workerId,
-        jobId,
-        message,
-        data,
-      });
-    } else if (status === 'reject') {
-      rejects[action](payload);
-      throw Error(
-        `${payload}
-
-        To get more informaion for debugging, please add logger in createWorker():
-
-        const worker = createWorker({
-          logger: ({ message }) => console.log(message),
-        });
-
-        Even more details:
-
-        const { setLogging } = require('@ffmpeg/ffmpeg');
-        setLogging(true);
-        `,
-      );
-    } else if (status === 'progress') {
-      parseProgress(payload, progress);
-      logger(payload);
-    }
-  });
-
-  return {
-    id,
-    worker,
-    setResolve,
-    setReject,
-    load,
-    write,
-    writeText,
-    read,
-    remove,
-    ls,
-    run,
-    transcode,
-    trim,
-    concatDemuxer,
-    terminate,
-  };
-};
diff --git a/src/index.js b/src/index.js
old mode 100755
new mode 100644
index ab96c68..36f717e
--- a/src/index.js
+++ b/src/index.js
@@ -1,9 +1,6 @@
 require('regenerator-runtime/runtime');
-const { logging, setLogging } = require('./utils/log');
-const createWorker = require('./createWorker');
+const createFFmpeg = require('./createFFmpeg');
 
 module.exports = {
-  logging,
-  setLogging,
-  createWorker,
+  createFFmpeg,
 };
diff --git a/src/node/defaultOptions.js b/src/node/defaultOptions.js
new file mode 100644
index 0000000..b3d3568
--- /dev/null
+++ b/src/node/defaultOptions.js
@@ -0,0 +1,8 @@
+const defaultOptions = require('../constants/defaultOptions');
+
+/*
+ * Default options for node environment
+ */
+module.exports = {
+  ...defaultOptions,
+};
diff --git a/src/worker/node/fetchFile.js b/src/node/fetchFile.js
similarity index 100%
rename from src/worker/node/fetchFile.js
rename to src/node/fetchFile.js
diff --git a/src/node/getModule.js b/src/node/getModule.js
new file mode 100644
index 0000000..51f54fa
--- /dev/null
+++ b/src/node/getModule.js
@@ -0,0 +1,6 @@
+module.exports = () => new Promise((resolve) => {
+  const Module = require('@ffmpeg/core');
+  Module.onRuntimeInitialized = () => {
+    resolve(Module);
+  };
+});
diff --git a/src/node/index.js b/src/node/index.js
new file mode 100644
index 0000000..85ade1f
--- /dev/null
+++ b/src/node/index.js
@@ -0,0 +1,9 @@
+const defaultOptions = require('./defaultOptions');
+const getModule = require('./getModule');
+const fetchFile = require('./fetchFile');
+
+module.exports = {
+  defaultOptions,
+  getModule,
+  fetchFile,
+};
diff --git a/src/utils/getId.js b/src/utils/getId.js
deleted file mode 100644
index 8c2b119..0000000
--- a/src/utils/getId.js
+++ /dev/null
@@ -1,3 +0,0 @@
-module.exports = (prefix, cnt) => (
-  `${prefix}-${cnt}-${Math.random().toString(16).slice(3, 8)}`
-);
diff --git a/src/utils/getTransferables.js b/src/utils/getTransferables.js
deleted file mode 100644
index 11c9112..0000000
--- a/src/utils/getTransferables.js
+++ /dev/null
@@ -1,16 +0,0 @@
-module.exports = (packet) => {
-  const transferables = [];
-  const check = (b) => {
-    if (b instanceof Uint8Array) {
-      transferables.push(b.buffer);
-    } else if (b instanceof ArrayBuffer) {
-      transferables.push(b);
-    }
-  };
-  const { payload: { args, data } } = packet;
-  check(data);
-  if (Array.isArray(args)) {
-    args.forEach((arg) => check(arg));
-  }
-  return transferables;
-};
diff --git a/src/utils/log.js b/src/utils/log.js
index 4faac26..34ef0ce 100644
--- a/src/utils/log.js
+++ b/src/utils/log.js
@@ -6,4 +6,4 @@ exports.setLogging = (_logging) => {
   logging = _logging;
 };
 
-exports.log = (...args) => (logging ? console.log.apply(this, args) : null);
+exports.log = (type, message) => (logging ? console.log(`[${type}] ${message}`) : null);
diff --git a/src/utils/resolvePaths.js b/src/utils/resolvePaths.js
index 93be72f..717d9fc 100644
--- a/src/utils/resolvePaths.js
+++ b/src/utils/resolvePaths.js
@@ -3,7 +3,7 @@ const resolveURL = isBrowser ? require('resolve-url') : s => s; // eslint-disabl
 
 module.exports = (options) => {
   const opts = { ...options };
-  ['corePath', 'workerPath'].forEach((key) => {
+  ['corePath'].forEach((key) => {
     if (typeof options[key] !== 'undefined') {
       opts[key] = resolveURL(opts[key]);
     }
diff --git a/src/worker-script/utils/str2ptr.js b/src/utils/string2pointer.js
similarity index 100%
rename from src/worker-script/utils/str2ptr.js
rename to src/utils/string2pointer.js
diff --git a/src/worker-script/utils/strList2ptr.js b/src/utils/stringList2pointer.js
similarity index 71%
rename from src/worker-script/utils/strList2ptr.js
rename to src/utils/stringList2pointer.js
index a3af49f..d9523cb 100644
--- a/src/worker-script/utils/strList2ptr.js
+++ b/src/utils/stringList2pointer.js
@@ -1,10 +1,10 @@
-const str2ptr = require('./str2ptr');
+const string2pointer = require('./string2pointer');
 
 module.exports = (Module, strList) => {
   const listPtr = Module._malloc(strList.length * Uint32Array.BYTES_PER_ELEMENT);
 
   strList.forEach((s, idx) => {
-    const strPtr = str2ptr(Module, s);
+    const strPtr = string2pointer(Module, s);
     Module.setValue(listPtr + (4 * idx), strPtr, 'i32');
   });
 
diff --git a/src/worker-script/browser/.eslintrc b/src/worker-script/browser/.eslintrc
deleted file mode 100644
index e88da2e..0000000
--- a/src/worker-script/browser/.eslintrc
+++ /dev/null
@@ -1,5 +0,0 @@
-{
-  "env": {
-    "worker": true
-  }
-}
diff --git a/src/worker-script/browser/getCore.js b/src/worker-script/browser/getCore.js
deleted file mode 100644
index 521d008..0000000
--- a/src/worker-script/browser/getCore.js
+++ /dev/null
@@ -1,6 +0,0 @@
-module.exports = (corePath) => {
-  if (typeof global.Module === 'undefined') {
-    global.importScripts(corePath);
-  }
-  return global.Module;
-};
diff --git a/src/worker-script/browser/index.js b/src/worker-script/browser/index.js
deleted file mode 100644
index 86fb0b5..0000000
--- a/src/worker-script/browser/index.js
+++ /dev/null
@@ -1,10 +0,0 @@
-const worker = require('..');
-const getCore = require('./getCore');
-
-global.addEventListener('message', ({ data }) => {
-  worker.dispatchHandlers(data, postMessage);
-});
-
-worker.setAdapter({
-  getCore,
-});
diff --git a/src/worker-script/index.js b/src/worker-script/index.js
deleted file mode 100644
index 57ebfef..0000000
--- a/src/worker-script/index.js
+++ /dev/null
@@ -1,96 +0,0 @@
-require('regenerator-runtime/runtime');
-const defaultArgs = require('./constants/defaultArgs');
-const strList2ptr = require('./utils/strList2ptr');
-const getTransferables = require('../utils/getTransferables');
-
-const NO_LOAD_ERROR = 'FFmpegCore is not ready, make sure you have completed Worker.load().';
-
-let action = 'unknown';
-let Module = null;
-let adapter = null;
-let ffmpeg = null;
-
-const load = ({ workerId, payload: { options: { corePath } } }, res) => {
-  if (Module === null) {
-    const Core = adapter.getCore(corePath);
-    Core()
-      .then(async (_Module) => {
-        Module = _Module;
-        Module.setLogger((message, type) => {
-          res.progress({
-            workerId, action, type, message,
-          });
-        });
-        ffmpeg = Module.cwrap('ffmpeg', 'number', ['number', 'number']);
-        res.resolve({ message: 'Loaded ffmpeg-core' });
-      });
-  } else {
-    res.resolve({ message: 'Loaded ffmpeg-core' });
-  }
-};
-
-const FS = ({
-  payload: {
-    method,
-    args,
-  },
-}, res) => {
-  if (Module === null) {
-    throw NO_LOAD_ERROR;
-  } else {
-    res.resolve({
-      message: `Complete ${method}`,
-      data: Module.FS[method](...args),
-    });
-  }
-};
-
-const run = ({
-  payload: {
-    args: _args,
-  },
-}, res) => {
-  if (Module === null) {
-    throw NO_LOAD_ERROR;
-  } else {
-    const args = [...defaultArgs, ..._args.trim().split(' ')].filter((s) => s.length !== 0);
-    ffmpeg(args.length, strList2ptr(Module, args));
-    res.resolve({
-      message: `Complete ${args.join(' ')}`,
-    });
-  }
-};
-
-exports.dispatchHandlers = (packet, send) => {
-  const { workerId, jobId, action: act } = packet;
-  const res = (status, payload) => {
-    const pkt = {
-      workerId,
-      jobId,
-      action: act,
-      status,
-      payload,
-    };
-    send(pkt, getTransferables(pkt));
-  };
-  res.resolve = res.bind(this, 'resolve');
-  res.reject = res.bind(this, 'reject');
-  res.progress = res.bind(this, 'progress');
-
-  action = act;
-  try {
-    ({
-      load,
-      FS,
-      run,
-    })[act](packet, res);
-  } catch (err) {
-    /** Prepare exception to travel through postMessage */
-    res.reject(err.toString());
-  }
-  action = 'unknown';
-};
-
-exports.setAdapter = (_adapter) => {
-  adapter = _adapter;
-};
diff --git a/src/worker-script/node/getCore.js b/src/worker-script/node/getCore.js
deleted file mode 100644
index af4bb5f..0000000
--- a/src/worker-script/node/getCore.js
+++ /dev/null
@@ -1,8 +0,0 @@
-let FFmpegCore = null;
-
-module.exports = () => {
-  if (FFmpegCore === null) {
-    FFmpegCore = require('@ffmpeg/core');
-  }
-  return FFmpegCore;
-};
diff --git a/src/worker-script/node/index.js b/src/worker-script/node/index.js
deleted file mode 100644
index 8f9baf1..0000000
--- a/src/worker-script/node/index.js
+++ /dev/null
@@ -1,16 +0,0 @@
-const { parentPort } = require('worker_threads');
-const worker = require('..');
-const getCore = require('./getCore');
-
-parentPort.on('message', (packet) => {
-  worker.dispatchHandlers(
-    packet,
-    (...args) => {
-      parentPort.postMessage(...args);
-    },
-  );
-});
-
-worker.setAdapter({
-  getCore,
-});
diff --git a/src/worker/browser/defaultOptions.js b/src/worker/browser/defaultOptions.js
deleted file mode 100644
index 61bd237..0000000
--- a/src/worker/browser/defaultOptions.js
+++ /dev/null
@@ -1,15 +0,0 @@
-const resolveURL = require('resolve-url');
-const { version, dependencies } = require('../../../package.json');
-const defaultOptions = require('../../constants/defaultOptions');
-
-/*
- * Default options for browser worker
- */
-module.exports = {
-  ...defaultOptions,
-  workerPath: (typeof process !== 'undefined' && process.env.FFMPEG_ENV === 'development')
-    ? resolveURL(`/dist/worker.dev.js?nocache=${Math.random().toString(36).slice(3)}`)
-    : `https://unpkg.com/@ffmpeg/ffmpeg@v${version}/dist/worker.min.js`,
-  corePath: `https://unpkg.com/@ffmpeg/core@v${dependencies['@ffmpeg/core'].substring(1)}/ffmpeg-core.js`,
-  workerBlobURL: true,
-};
diff --git a/src/worker/browser/index.js b/src/worker/browser/index.js
deleted file mode 100644
index 467d4bb..0000000
--- a/src/worker/browser/index.js
+++ /dev/null
@@ -1,20 +0,0 @@
-/**
- *
- * Tesseract Worker adapter for browser
- *
- * @fileoverview Tesseract Worker adapter for browser
- * @author Kevin Kwok <antimatter15@gmail.com>
- * @author Guillermo Webster <gui@mit.edu>
- * @author Jerome Wu <jeromewus@gmail.com>
- */
-const defaultOptions = require('./defaultOptions');
-const spawnWorker = require('./spawnWorker');
-const onMessage = require('./onMessage');
-const fetchFile = require('./fetchFile');
-
-module.exports = {
-  defaultOptions,
-  spawnWorker,
-  onMessage,
-  fetchFile,
-};
diff --git a/src/worker/browser/onMessage.js b/src/worker/browser/onMessage.js
deleted file mode 100644
index ec74783..0000000
--- a/src/worker/browser/onMessage.js
+++ /dev/null
@@ -1,5 +0,0 @@
-module.exports = (worker, handler) => {
-  worker.onmessage = ({ data }) => { // eslint-disable-line
-    handler(data);
-  };
-};
diff --git a/src/worker/browser/spawnWorker.js b/src/worker/browser/spawnWorker.js
deleted file mode 100644
index 5ae4ccb..0000000
--- a/src/worker/browser/spawnWorker.js
+++ /dev/null
@@ -1,20 +0,0 @@
-/**
- * spawnWorker
- *
- * @name spawnWorker
- * @function create a new Worker in browser
- * @access public
- */
-module.exports = ({ workerPath, workerBlobURL }) => {
-  let worker;
-  if (Blob && URL && workerBlobURL) {
-    /* Use Blob to load cross domain worker script */
-    const blob = new Blob([`importScripts("${workerPath}");`], {
-      type: 'text/javascript',
-    });
-    worker = new Worker(URL.createObjectURL(blob));
-  } else {
-    worker = new Worker(workerPath);
-  }
-  return worker;
-};
diff --git a/src/worker/node/defaultOptions.js b/src/worker/node/defaultOptions.js
deleted file mode 100644
index 053c1e3..0000000
--- a/src/worker/node/defaultOptions.js
+++ /dev/null
@@ -1,10 +0,0 @@
-const path = require('path');
-const defaultOptions = require('../../constants/defaultOptions');
-
-/*
- * Default options for node worker
- */
-module.exports = {
-  ...defaultOptions,
-  workerPath: path.join(__dirname, '..', '..', 'worker-script', 'node', 'index.js'),
-};
diff --git a/src/worker/node/onMessage.js b/src/worker/node/onMessage.js
deleted file mode 100644
index 7100e71..0000000
--- a/src/worker/node/onMessage.js
+++ /dev/null
@@ -1,3 +0,0 @@
-module.exports = (worker, handler) => {
-  worker.on('message', handler);
-};
diff --git a/src/worker/node/spawnWorker.js b/src/worker/node/spawnWorker.js
deleted file mode 100644
index 5bba13c..0000000
--- a/src/worker/node/spawnWorker.js
+++ /dev/null
@@ -1,12 +0,0 @@
-const { Worker } = require('worker_threads');
-
-/**
- * spawnWorker
- *
- * @name spawnWorker
- * @function fork a new worker thread in node
- * @access public
- */
-module.exports = ({ workerPath }) => (
-  new Worker(workerPath)
-);
diff --git a/tests/assets/StarWars3.wav b/tests/assets/StarWars3.wav
new file mode 100644
index 0000000..1a2dd7a
Binary files /dev/null and b/tests/assets/StarWars3.wav differ
diff --git a/tests/constants.js b/tests/constants.js
index af74d63..0e7a163 100644
--- a/tests/constants.js
+++ b/tests/constants.js
@@ -1,11 +1,9 @@
-const TIMEOUT = 30000;
+const TIMEOUT = 60000;
 const BASE_URL = 'http://localhost:3000/tests/assets';
 const IS_BROWSER = typeof window !== 'undefined' && typeof window.document !== 'undefined';
 const OPTIONS = {
   corePath: '../node_modules/@ffmpeg/core/ffmpeg-core.js',
-  ...(IS_BROWSER ? { workerPath: '../dist/worker.dev.js' } : {}),
 };
-const FLAME_MP4_LENGTH = 100374;
 
 if (typeof module !== 'undefined') {
   module.exports = {
@@ -13,6 +11,5 @@ if (typeof module !== 'undefined') {
     BASE_URL,
     IS_BROWSER,
     OPTIONS,
-    FLAME_MP4_LENGTH,
   };
 }
diff --git a/tests/ffmpeg.test.js b/tests/ffmpeg.test.js
index 56258e9..337a2e5 100644
--- a/tests/ffmpeg.test.js
+++ b/tests/ffmpeg.test.js
@@ -1,20 +1,27 @@
-const { createWorker } = FFmpeg;
-const worker = createWorker(OPTIONS);
+const { createFFmpeg } = FFmpeg;
+const ffmpeg = createFFmpeg(OPTIONS);
 
 before(async function cb() {
   this.timeout(0);
-  await worker.load();
+  await ffmpeg.load();
 });
 
 describe('transcode()', () => {
   describe('should transcode different format', () => {
-    ['flame.avi'].forEach((name) => (
-      it(`transcode ${name}`, async () => {
-        await worker.write(name, `${BASE_URL}/${name}`);
-        await worker.transcode(name, 'output.mp4');
-        const { data } = await worker.read('output.mp4');
-        expect(data.length).to.be(FLAME_MP4_LENGTH);
-      }).timeout(TIMEOUT)
-    ));
+    [1, 2, 4].forEach((n) => {
+      [
+        { from: 'flame.avi', to: 'flame.mp4' },
+        { from: 'flame.avi', to: 'flame.webm' },
+        { from: 'StarWars3.wav', to: 'StarWars3.mp3' },
+      ].forEach(({ from, to }) => (
+        it(`transcode ${from} to ${to} (${n} threads)`, async () => {
+          await ffmpeg.write(from, `${BASE_URL}/${from}`);
+          await ffmpeg.transcode(from, to, `-threads ${n}`);
+          const data = ffmpeg.read(to);
+          ffmpeg.remove(to);
+          expect(data.length).not.to.be(0);
+        }).timeout(TIMEOUT)
+      ));
+    });
   });
 });