diff --git a/CheckWebsiteAlive.java b/CheckWebsiteAlive.java
index 259f6ce..eb34d6b 100644
--- a/CheckWebsiteAlive.java
+++ b/CheckWebsiteAlive.java
@@ -2,130 +2,249 @@
 import java.net.HttpURLConnection;
 import java.net.URL;
 import java.util.ArrayList;
+import java.util.List;
 
 public class CheckWebsiteAlive {
-    private static final String[] DEAD_PHRASES = new String[]{
-            "is expired and be suspended",
-            "hosting for this domain is not configured",
-            "cannot connect"
-    };
-
-    private static ArrayList<String> listUrl = new ArrayList<>();
-    private static ArrayList<String > listOfDeadPhrases = new ArrayList<>();
-
-    public static void main(String[] args) {
-        System.out.println("******");
-        System.out.println("This program will help you to check if a website from a list is dead or alive. To see the instruction, please visit: https://github.com/scorta/CheckWebsiteAlive");
-        System.out.println("******");
-        System.out.println("Start working...");
-        String inputFile = "input.txt";
-        String deadPhrasesFile = "dead_phrases.txt";
-        StringBuilder result = new StringBuilder();
-        if(args.length > 0){
-            inputFile = args[0];
-        }
-
-        if(args.length > 1){
-            deadPhrasesFile = args[1];
-        }
-
-        listUrl = importList(inputFile);
-        listOfDeadPhrases = importList(deadPhrasesFile);
-
-        for(String url : listUrl){
-            result.append(url);
-            result.append("\t");
-            result.append(isDead(url));
-            result.append("\n");
-        }
-        writeOutput(inputFile, result.toString());
-    }
-
-    private static void forceExit(){
-        System.out.println("This program has encountered an error and will now exit.");
-        System.exit(1);
-    }
-
-    private static void writeOutput(String fileName, String content){
-        try{
-            PrintWriter output = new PrintWriter(fileName + "_out.txt");
-            output.print(content);
-            output.close();
-            System.out.println("Done. Please check the output file. It is named " + fileName + "_out.txt");
-        } catch (Exception e){
-            System.out.println("Error while writing result: " + e.toString());
-            forceExit();
-        }
-    }
-
-    private static ArrayList<String> importList(String fileName){
-        try{
-            ArrayList<String> list = new ArrayList<>();
-            BufferedReader br = new BufferedReader(new FileReader(fileName));
-            for(String line; (line = br.readLine()) != null;){
-                list.add(line);
-            }
-            return list;
-        } catch (Exception e){
-            System.out.println("Error while reading list: " + e.toString());
-            forceExit();
-            return null;
-        }
-    }
-
-    private static boolean isDead(String url) {
-        if (SocketConnection.htmlStatusCode(url, 5) >= 300 || SocketConnection.htmlStatusCode(url, 5) < 200)
-            return true;
-        String urlContent = SocketConnection.getURLSource(url, 10).toLowerCase();
-        for (String deadPhrase : listOfDeadPhrases) {
-            if (urlContent.contains(deadPhrase))
-                return true;
-        }
-        return false;
-    }
+    // this DEAD_PHRASES is obsoleted, for reference only. The program will use a dead phrases from text file
+	private static final String[] DEAD_PHRASES = new String[]{
+			"is expired and be suspended",
+			"hosting for this domain is not configured",
+			"cannot connect"
+	};
+
+	private static List<String> listUrl = new ArrayList<>();
+	private static List<String> listOfDeadPhrases = new ArrayList<>();
+
+	public static void main(String[] args) {
+		System.out.println("******");
+		System.out.println("This program will help you to check if a website from a list is dead or alive. To see the instruction, please visit: https://github.com/scorta/CheckWebsiteAlive");
+		System.out.println("******");
+		System.out.println("Start working...");
+
+		String inputFile = "input.txt";
+		String deadPhrasesFile = "dead_phrases.txt";
+		StringBuilder result = new StringBuilder();
+
+		if (args.length != 4) {
+			System.out.println("Must have 4 params: file name that contains list of urls, " +
+					"and file name that contains list of dead phrases, number of thread(s), " +
+					"and choice (0 == checking url alive, 1 == get page source)");
+			return;
+		}
+
+		inputFile = args[0];
+		listUrl = importList(inputFile);
+
+		if (listUrl.size() == 0) {
+			System.out.println("NO URLS, will exit now");
+			return;
+		}
+
+		deadPhrasesFile = args[1];
+		listOfDeadPhrases = importList(deadPhrasesFile);
+
+		if (listOfDeadPhrases.size() == 0) {
+			System.out.println("WARN: no dead phrases imported, are you sure?");
+		}
+		CheckUrl.listOfDeadPhrases = listOfDeadPhrases;
+
+		int numberOfThreads = Integer.parseInt(args[2]);
+		if (numberOfThreads < 1) {
+			System.out.println("WARN: 0 thread? Will use 1 now");
+			numberOfThreads = 1;
+		}
+
+		int choice = Integer.parseInt(args[3]);
+		Thread[] listThread = new Thread[numberOfThreads];
+		{
+			int start, end = 0, step;
+			step = 1 + listUrl.size() / numberOfThreads;
+
+			for (int i = 0; i < numberOfThreads; ++i) {
+				start = end;
+				end = start + step;
+				if (end >= listUrl.size()) {
+					end = listUrl.size() - 1;
+				}
+				System.out.println("Thread " + i + " covers " + start + " " + end);
+				if (choice == 0) {
+					listThread[i] = new Thread(new CheckUrlAliveThread("Thread " + i, listUrl, result, start, end));
+				} else {
+					listThread[i] = new Thread(new GetPageSourceThread("Thread " + i, listUrl, result, start, end));
+				}
+				listThread[i].start();
+			}
+		}
+
+		for (int i = 0; i < numberOfThreads; ++i) {
+			try {
+				listThread[i].join();
+			} catch (InterruptedException e) {
+				e.printStackTrace();
+			}
+		}
+
+		writeOutput(inputFile, result.toString());
+	}
+
+	private static void forceExit() {
+		System.out.println("This program has encountered an error and will now exit.");
+		System.exit(1);
+	}
+
+	private static void writeOutput(String fileName, String content) {
+		try {
+			if (content.isEmpty()) {
+				System.out.println("WARN: Empty content");
+				return;
+			}
+
+			PrintWriter output = new PrintWriter(fileName + "_out.txt");
+			output.print(content);
+			output.close();
+			System.out.println("Done. Please check the output file. It is named " + fileName + "_out.txt");
+		} catch (Exception e) {
+			System.out.println("Error while writing result: " + e.toString());
+			forceExit();
+		}
+	}
+
+	private static ArrayList<String> importList(String fileName) {
+		try {
+			ArrayList<String> list = new ArrayList<>();
+			BufferedReader br = new BufferedReader(new FileReader(fileName));
+			for (String line; (line = br.readLine()) != null; ) {
+				list.add(line);
+			}
+			return list;
+		} catch (Exception e) {
+			System.out.println("Error while reading list: " + e.toString());
+			forceExit();
+			return null;
+		}
+	}
+}
+
+class CheckUrlAliveThread implements Runnable {
+	private final String threadName;
+	private final List<String> listUrl;
+	private final StringBuilder res;
+	private final int start;
+	private final int end;
+
+	@Override
+	public void run() {
+		for (int i = start; i < end; ++i) {
+			StringBuilder sbTemp = new StringBuilder();
+			sbTemp.append(listUrl.get(i));
+			sbTemp.append("\t");
+			System.out.println(threadName + " is checking: " + listUrl.get(i));
+			String livingStatus = CheckUrl.isDead(listUrl.get(i)) ? "DEAD" : "ALIVE";
+			System.out.println(threadName + " is DONE checking: " + listUrl.get(i));
+			sbTemp.append(livingStatus);
+			sbTemp.append("\n");
+			synchronized (res) {
+				res.append(sbTemp);
+			}
+		}
+		System.out.println(threadName + " done!");
+	}
+
+	public CheckUrlAliveThread(String name, List<String> listUrl, StringBuilder res, int start, int end) {
+		this.threadName = name;
+		this.listUrl = listUrl;
+		this.res = res;
+		this.start = start;
+		this.end = end;
+	}
+}
+
+class CheckUrl {
+	public static List<String> listOfDeadPhrases;
+
+	public static boolean isDead(String url) {
+		boolean isDeadHttps = isDeadHelper("https://" + url);
+		boolean isDeadHttp = isDeadHelper("http://" + url);
+
+		return isDeadHttps && isDeadHttp;
+	}
+
+	public static boolean isDeadHelper(String url) {
+		int htmlStatusCode = SocketConnection.htmlStatusCode(url);
+		if (htmlStatusCode >= 301 || htmlStatusCode < 200) {
+			return true;
+		}
+		String urlContent = SocketConnection.getURLSource(url);
+		if (urlContent.length() < 10) {
+			return true;
+		}
+		for (String deadPhrase : listOfDeadPhrases) {
+			if (urlContent.contains(deadPhrase)) {
+				return true;
+			}
+		}
+		return false;
+	}
 }
 
 class SocketConnection {
-    public static int htmlStatusCode(String url, int timeOut){
-        try {
-            URL urlObject = new URL(url);
-            HttpURLConnection huc = (HttpURLConnection) urlObject.openConnection();
-            HttpURLConnection.setFollowRedirects(true);
-            huc.setConnectTimeout(timeOut * 1000);
-            huc.setRequestMethod("HEAD");  //OR  huc.setRequestMethod ("HEAD");
-            huc.connect();
-            return  huc.getResponseCode();
-        } catch (Exception e){
-            return 404;
-        }
-    }
-
-    public static String getURLSource(String url, int timeOut){
-        try {
-            URL urlObject = new URL(url);
-            HttpURLConnection huc = (HttpURLConnection) urlObject.openConnection();
-            HttpURLConnection.setFollowRedirects(false);
-            huc.setConnectTimeout(timeOut * 1000);
-            huc.setRequestMethod("GET");
-            huc.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1.2) Gecko/20090729 Firefox/3.5.2 (.NET CLR 3.5.30729)");
-            huc.connect();
-            return toString(huc.getInputStream());
-        } catch (Exception e){
-            return "cannot connect. Error: " + e.toString();
-        }
-    }
-
-    private static String toString(InputStream inputStream){
-        try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"))) {
-            String inputLine;
-            StringBuilder stringBuilder = new StringBuilder();
-            while ((inputLine = bufferedReader.readLine()) != null) {
-                stringBuilder.append(inputLine);
-            }
-
-            return stringBuilder.toString();
-        } catch (Exception e){
-            return "Error: " + e.toString();
-        }
-    }
+	public static final int timeOut = 3;
+
+	public static int htmlStatusCode(String url) {
+		try {
+			URL urlObject = new URL(url);
+			HttpURLConnection huc = (HttpURLConnection) urlObject.openConnection();
+			HttpURLConnection.setFollowRedirects(false);
+			huc.setConnectTimeout(timeOut * 1000);
+			huc.setReadTimeout(timeOut * 1000);
+			huc.setRequestMethod("HEAD");
+			huc.setRequestProperty("User-Agent", "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.87 Safari/537.36");
+			huc.connect();
+			return huc.getResponseCode();
+		} catch (Exception e) {
+			e.printStackTrace();
+			return 999;
+		}
+	}
+
+	public static String getURLSource(String url) {
+		try {
+			URL urlObject = new URL(url);
+			HttpURLConnection huc = (HttpURLConnection) urlObject.openConnection();
+			HttpURLConnection.setFollowRedirects(false);
+			huc.setConnectTimeout(timeOut * 1000);
+			huc.setRequestMethod("GET");
+			huc.setRequestProperty("User-Agent", "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.87 Safari/537.36");
+			huc.connect();
+			return toString(huc.getInputStream());
+		} catch (Exception e) {
+			return "cannot connect. Error: " + e.toString();
+		}
+	}
+
+
+	private static String toString(InputStream inputStream) {
+		try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"))) {
+			String inputLine;
+			StringBuilder stringBuilder = new StringBuilder();
+			while ((inputLine = bufferedReader.readLine()) != null) {
+				stringBuilder.append(inputLine);
+				stringBuilder.append("\n");
+			}
+			replaceAll(stringBuilder, "\n", " ");
+
+			return stringBuilder.toString().toLowerCase();
+		} catch (Exception e) {
+			return "Error: " + e.toString();
+		}
+	}
+
+	private static void replaceAll(StringBuilder builder, String from, String to) {
+		int index = builder.indexOf(from);
+		while (index != -1) {
+			builder.replace(index, index + from.length(), to);
+			index += to.length(); // Move to the end of the replacement
+			index = builder.indexOf(from, index);
+		}
+	}
 }