- ACL-COMPAT - ACL-COMPAT is a free set of compatibility layers for parts of Franz's ACL system programming API for several Common Lisp implementations
- atomics - Portability layer for atomic operations like compare-and-swap (CAS)
- ccl-compat - Clozure CL compatibility module
- cl-configuration - CL-CONFIGURATION is a package that provides a macro (DEFCONFIGURATION) which can be used to set up various logical pathnames in an elegant way
- CLAD - The Common Lisp Application Directories (CLAD) library is a simple API
- editor-hints - The estimable Tobias C Rittweiler is working to develop a CL library called editor hints that aims at giving a portable facility for a Lisp implementation to tell the development environment things about its state
- global-vars - Define efficient global variables in Common Lisp
- nontrivial-gray-streams - Like trivial-gray-streams but:
- Portable Exit - A portability layer for ending the Lisp image
- Portable-Threads - Portable-threads is the GBBopen project's portable-thread code all packaged up for ASDF-Install
- ppath - A path manipulation library inspired by Python's os.path
- trivial-arguments - Tiny CL library to retrieve the arguments list of a function
- trivial-cltl2 - Compatibility package exporting CLtL2 functionality
- trivial-macroexpand-all - Provides a macroexpand-all function that calls the implementation-specific equivalent
- with-user-abort - Provides a portable way to handle Control-C in Lisp
compatibility layers