diff --git a/docs/source/appendix/auxlibs.rst b/docs/source/appendix/auxlibs.rst
index 4c845f197..321cb52c4 100644
--- a/docs/source/appendix/auxlibs.rst
+++ b/docs/source/appendix/auxlibs.rst
@@ -4,8 +4,6 @@ Auxiliary libraries
 The Yosys source distribution contains some auxiliary libraries that are
 compiled into Yosys and can be used in plugins.
 
-.. TODO:: fill out the newer auxiliary libs
-
 BigInt
 ------
 
@@ -20,30 +18,50 @@ See also: http://mattmccutchen.net/bigint/
 dlfcn-win32
 -----------
 
-The files in ``libs/dlfcn-win32`` provide...
+The ``dlfcn`` library enables runtime loading of plugins without requiring
+recompilation of Yosys.  The files in ``libs/dlfcn-win32`` provide an
+implementation of ``dlfcn`` for Windows.
+
+See also: https://github.com/dlfcn-win32/dlfcn-win32
 
 ezSAT
 -----
 
 The files in ``libs/ezsat`` provide a library for simplifying generating CNF
 formulas for SAT solvers. It also contains bindings of MiniSAT. The ezSAT
-library is written by C. Wolf. It is used by the sat pass (see
-:doc:`../cmd/sat`).
+library is written by C. Wolf. It is used by the :cmd:ref:`sat` pass (see
+:doc:`/cmd/sat`).
 
 fst
 ---
 
-The files in ``libs/fst`` provide...
+``libfst`` files from `gtkwave`_ are included in ``libs/fst`` to support
+reading/writing signal traces from/to the GTKWave developed FST format.  This is
+primarily used in the :cmd:ref:`sim` command.
+
+.. _gtkwave: https://github.com/gtkwave/gtkwave
 
 json11
 ------
 
-The files in ``libs/json11`` provide...
+For reading/writing designs from/to JSON, :cmd:ref:`read_json` and
+:cmd:ref:`write_json` should be used.  For everything else there is the `json11
+library`_:
+
+   json11 is a tiny JSON library for C++11, providing JSON parsing and
+   serialization.
+
+This library is used for outputting machine-readable statistics (:cmd:ref:`stat`
+with ``-json`` flag), using the RPC frontend (:cmd:ref:`connect_rpc`), and the
+yosys-witness ``yw`` format.
+
+.. _json11 library: https://github.com/dropbox/json11
 
 MiniSAT
 -------
 
-The files in ``libs/minisat`` provide...
+The files in ``libs/minisat`` provide a high-performance SAT solver, used by the
+:cmd:ref:`sat` command.
 
 SHA1
 ----