TweetAdder has trial version. You can have 250 twitter followers for free at the start, if I am not mistaken.
And what results have you seen from using this?
Ideally people / companies are screening who they follow for some relevancy back… I think twitter wants this as well, otherwise the odds that you’re actually reading your feed are slim and that is part of the goal.
The follow me i will follow you back process can increase your twitter followers but it will not serve the purpose. The actual purpose of followers is to have engagement and if you are publisher etc then you need promotion from the followers. Try to get the targeted followers.
There are many, just google them, but they will lead your account to be temporarily or permanently banned.
i think better way is … you use forum or ur FB account for that …you can put twitter id here …& request to all of em please follow me Twitter , also i will follow u back … give & take 
Why would you follow just anyone back? How does that add value to you… or for them?
said that coz who want to increase his/her follower …
What good is it to send updates to people who do not act on them, share them, or otherwise engage with you about them or vise-veras? No magic awards or keys are awarded for going from 50 to 51 or 50,000 to 50,001.
Your gross number of followers is nearly meaningless in actually driving return. So unless you have a need for bragging rights, and even then picking up one or two followers at a time is hardly the way to go about it, stick to quality first.
Well i don’t think any one prefer these kind of tools.Because any time twitter or any site detect it you ca be banned and your time and work become useless.So it is recommended to go for ethical ways to get quality traffic.
Twitter people will only follow you if the content in your Twitter account may be of relevance to them, or if they’re interested on it… Try to post things/topics that you think many people are interested in… A good exercise is to follow only the pages you think the people are mostly interested in
Given the fact that this thread was started in January, I think it has run its course. Thread closed.
Here is one tool TweetAdder which is automatically build up your twitter follower but any tools or software are not good for our site traffic.
Yes there is but I don’t think it’s effective because after an hour you already lose some of them.