1. UCW Tricks and Cookbook
    Creating a "modal" component
  2. UfasoftCommonLisp
    Ufasoft Common Lisp development system
  3. uffi
    CFFI is recommended as the replacement for UFFI.
  4. ugly-tiny-infix-macro
    This is a powerful lisp macro for the purpose of writing your expressions in infix notation while not losing out on lisp's power
  5. uiop
    UIOP, the Utilities for Implementation- and OS- Portability, is a portability layer and basic utility library that comes as part of ASDF 3
  6. ulimyhmpqs
    ulimyhmpqs is an implementation of the Hypercube Multiple Polynomial Quadratic Sieve (HMPQS), an algorithm for the factorisation of large (up to about 110 digits, where the Number Field Sieve (NFS) algorithms become more efficient) integers
  7. uLisp
    uLisp is an embedded Lisp for microcontrollers, supporting Arduino, Adafruit M0/M4, Micro:bit, ESP8266/32, and RISC-V boards
  8. umlisp
    umlisp is an CLOS object-oriented interface to the Unified Medical Language System
  9. umpa-lumpa
    Umpa-Lumpa is a set of utilities used by armish and liards
  10. unicly
    UUIDs (Universally Unique Identifiers) v1-v5 per RFC 4122