1. StatusNet(Laconica)
StatusNet is a Twitter clone, built with PHP + MySQL. It’s an opensource microblogging application, widely used by lots of microblog sites, such as Twitterfeed, Hellotxt and Gravity. It’s mature and it offers a smooth usage. The source can be found here.
2. Jaiku Engine
Jaiku was the microblogging site of Google. However, they decided no longer to develop the code but make it open source under the name JaikuEngine. Anyone can setup and run their own Jaiku on GAE. There is an open source mobile client & frontend.
3. Yonkly
Yonkly is an Asp.Net-powered Twitter-clone for creating your own microblogging community network.Besides the open source version, it has a hosted & an advanced standalone version.
4. Floopo
This free microblogging script is built with PHP & MySQL.It functions very similar to Twitter & provides a powerful backend to manage the whole system. The office site is http://www.floopo.com/.
5. Jisko
Jisko is a PHP microblogging application that offers a Twitter-like API for developing it further. Users can have their profile pages, message with each other easily & Jisko is compatible with mobile devices. It can be found here.
6. PageCookery
PageCookery is a single-user microblog which can pull data from social networks like Flickr, last.fm, etc. It offers an Ajaxed interface where users can comment to the entries easily.P.S. The original page is Chinese. However, you can view the English version behind Google Translate.
7. EchoWaves
EchoWaves is a ready-to-use hosted application where the source code is offered for free. It is a collaboration tool & a social network which is focused to conversations rather than the users.
8. P2 Wordpress Theme
This is a Wordpress theme which can convert your blogging engine into a Twitter-like interface.It has real-time updates where new posts & comments come in without reloading. There are also inline comments, posting from homepage & more.
9. Motion
TypePad Motion enables publishers and marketers to create vibrant, branded communities that deepen loyalty and increase
page views while giving you total control of your brand. It is based on Pownce & MovableType Motion and built with Django.
10. Blurt.it
Blurt.it is a fresh microblogging application that requires PHP/MySQL to run. Very similar to Twitter, users can easily connect with each other with open or private threads. Source
11. Asaph
Asaph is a micro-blogging system, focusing on collecting links and images from other pages. It allows you to post content directly from any page you are on. Asaph is not a full blown blog and it does not aim to be one – it just does this one task, but it’s pretty good at it. the source code can be found here:http://www.phoboslab.org/projects/asaph .
12. Sharetronix
Sharetronix is an open source microblogging system, built with PHP and MySQL. Demo Download the source code
