I have written a couple of planners as part of my research. A short description of these planners is given below

• CPP: CPP is a constraint logic based planner with preferences. The syntax of the input is the AL language (Baral & Gefond 2000).  The language for specifying preferences is PP (Son & Pontelli). The source code of CPP and some testing domains can be downloaded here. To run the planner, GNU prolog is needed.
   
• CPA: CPA is a conformant planner based on approximation semantics. The input language of the planner is AL (Baral & Gefond 2000). CPA employs the best first search strategy with repeated state avoidance and the number of fulfilled subgoals as the heuristic function. CPA was written in C++. For more information about CPA, see the paper (Son, Tu, Gelfond & Morales, AAAI05).
  
  The binary code of CPA and some testing domains can be downloaded here.
   
• CPA⁺: CPA⁺ is a sound and complete conformant planner based on the idea of the 0-approximation. It automatically detects necessary unknown fluents to split the set of initial partial states into another set of partial states in order to guarantee the completeness.
  
  The implementation of CPA⁺ is built on the top of CPA. Inherited from CPA, CPA⁺ is a best first search planner using the number of fulfilled subgoals as the heuristic function. For more details about CPA⁺, pls see the paper (Son & Tu, KR 2006).
  
  The binary code of CPA⁺ and some testing domains can be downloaded here.
   
• ASCP:  ASCP is an answer set programming based conditional planner capable of generating both conformant plans and conditional plans in the presence of sensing actions, incomplete information about the initial state, and static causal laws. For more information, see the paper (Tu, Son & Baral, TPLP06).
  
  The translator ASCP and some testing domains can be downloaded here.
   
• CP_ASP: CP_ASP is a answer set planning framework where a planning problem is translated into a logic program whose answer sets correspond to solutions to the planning problem. The translation is described in the paper (Son, Tu, Gelfond & Morales, LPNMR05)
  
  Some testing domains and their translations into logic programs can be found here.