Of multifarious keyloggers in the market, which one fits your special need and meets all your requirements? How to choose the right
Keylogger for you? Before we compare the pros and cos of the two mainstream keylogging programs, you should try to get the answers for the following questions. Your replies will tell on which security level you require for the monitoring process.
What shall be considered before purchasing a keylogger?
1.Are you legally using a keylogger?
2.Is the information you try to record sensitive?
3.Are there many users share the same computer?
4.You need only to log the incoming info or also the outgoing data?
5.Do you want the screenshot function?
6.Do you want to completely hide the program?
7.Does the computer have USB ports or floppy drive attached?
8.Will the PC be moved regularly?
9.Are you authorized to install any program in the PC?
10.It’s a short term or long term surveillance?
11.How much you can accept to purchase a keylogger?
* Keylogger with screen capturing function somehow will slow down the PC and alert the users of knowing they are being spied. The operating system will crash if the PC with no enough hard drive space.
How to choose an undetectable keylogger?
Basically, there are two main keyloggers:
software keylogger and hardware keylogger. We will give you a general idea of their own unique features so that you will know which one fits you most.
1) Software keyloggers 
Normally before you decide to buy a keylogging program you can try the trial version so check if it's the one you want. Most of the keyloggers with the capability of recording all computer activities include websites visited, clipboard texts, keystrokes (bank, mailbox, game, Facebook, Twitter's usernames & passwords), application launched and more. You can pre-set an email address as some keyloggers allow to auto-send logs to the specified mailbox. However, his might be caught by anti-virus or anti keylogger program. Also screen capturing is an added function of software keylogger for the convenience of the installer. But if you are monitoring a low configuration computer, be cautious since it may cause system instability.
Some keyloggers are visible in the task manager and some are not. Even so, it doesn't mean the invisible one could never be detected by spyware scanning program. Some spywares also build up a database update network as to keep the program to scan the newest released keyloggers.
Logs recorded by all keyloggers are stored in the computer local. Some logs might be encrypted so nobody else can edit and read. You may either copy the log from the hard drive or access via internet.
2) Hardware keyloggers 
Applying a hardware keylogger to monitor online activity is as easy as plug a USB wire into the port. No experience required.
After connecting a hardware keylogger, every keystroke that passes through it will be recorded into its own internal memory.
You don’t need a software to assist you to complete the spying process. The hardware keylogger itself allows you to
record and extract logs within its memory. A hardware keylogger is thoroughly undetectable by and anti-virus software or spyware scanner thus if anyone wants a long-term secret surveillance may consider this.
Using a hardware
keylogger you don’t need to worry about being detected by the users as it will hardly caused the operating system to crack down. All the recorded logs would be stored in its internal memory chip so nobody could access or copy the records.
There are two types of hardwares--unsecured onboard memory and encrypted onboard memory. As we can tell from the names, the latter is more secure since others could not read what the encrypted logs.
Conclusion:
There are both pros and cons of software keylogger and hardware keylogger. Consider and think carefully about the questions from the beginning and make your right choice!
