diff --git a/src/Makefile b/src/Makefile
index 5d4a6f1..409d9d4 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -58,6 +58,8 @@ HACKERBASE-OBJS=hackerbase.o testing.o listing.o cal-month.o		\
 	 template-list-expander.o box-drawing.o util-list.o		\
 	 export-web-static.o util-dir.o racket-kwargs.o dokuwiki.o
 
+GENDOC-OBJS=gendoc.o duck-extract.o
+
 .PHONY: imports
 imports: $(HACKERBASE-DEPS)
 
@@ -84,6 +86,9 @@ install-dev: static
 	install -m 0755 -d /usr/local/man/man1
 	install -m 0755 ../doc/hackerbase.1 /usr/local/man/man1/hackerbase-dev.1
 
+../gendoc: $(GENDOC-OBJS)
+	$(CSC) -strip -static -o $@ $(GENDOC-OBJS)
+
 ################################################################
 # Module static and shared object and import source compilation
 
@@ -94,10 +99,14 @@ install-dev: static
 	$(CSC) -regenerate-import-libraries -P -J $<
 
 ################################################################
-# Main program
+# Main programs
 
 hackerbase.o: $(HACKERBASE-DEPS)
 
+GENDOC-SOURCES=gendoc.scm duck-extract.import.scm
+
+gendoc.o: $(GENDOC-SOURCES)
+
 ################################################################
 # Modules
 
@@ -495,3 +504,8 @@ dokuwiki.import.scm: $(DOKUWIKI-SOURCES)
 DUCK-SOURCES=duck.scm
 
 duck.import.scm: $(DUCK-SOURCES)
+
+DUCK-EXTRACT-SOURCES=duck-extract.scm
+
+duck-extract.o: duck-extract.import.scm
+duck-extract.import.scm: $(DUCK-EXTRACT-SOURCES)
diff --git a/src/duck-extract.scm b/src/duck-extract.scm
new file mode 100644
index 0000000..88a4f3d
--- /dev/null
+++ b/src/duck-extract.scm
@@ -0,0 +1,92 @@
+;;
+;; duck-extract.scm
+;;
+;; Duck - a CHICKEN in-source documentation: extraction tool.
+;;
+;; ISC License
+;;
+;; Copyright 2023 Dominik Pantůček <dominik.pantucek@trustica.cz>
+;;
+;; Permission to use, copy, modify, and/or distribute this software
+;; for any purpose with or without fee is hereby granted, provided
+;; that the above copyright notice and this permission notice appear
+;; in all copies.
+;; 
+;; THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+;; WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+;; WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+;; AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
+;; CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+;; OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+;; NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+;; CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+;;
+
+(declare (unit duck-extract))
+
+(module
+ duck-extract
+ (
+  print-module-duck
+  )
+
+ (import scheme
+	 (chicken base)
+	 (chicken string)
+	 (chicken format))
+
+ (define (print-duck-text dt)
+   (print
+    (string-intersperse
+     (map (lambda (x)
+	    (format "~A" x))
+	  dt)
+     " ")))
+
+ (define (print-duck-module sec)
+   (print "## " (cadr sec) " [module]")
+   (newline)
+   (print-duck-text (caddr sec)))
+
+ (define (print-duck-variable sec)
+   (newline)
+   (print "### " (cadr sec) " [variable]")
+   (newline)
+   (print "    (define " (cadr sec) " " (cadddr sec) ")")
+   (newline)
+   (print-duck-text (caddr sec)))
+
+ (define (print-duck-parameter sec)
+   (newline)
+   (print "### " (cadr sec) " [parameter]")
+   (newline)
+   (print "    (define " (cadr sec) " (make-parameter " (list-ref sec 4) "))")
+   (print "    (" (cadr sec) ")")
+   (print "    (" (cadr sec) " " (cadddr sec) ")")
+   (newline)
+   (print-duck-text (caddr sec)))
+
+ (define (print-duck-procedure sec)
+   (newline)
+   (print "### " (cadr sec) " [procedure]")
+   (newline)
+   (print "    " (cons (cadr sec) (cadddr sec)))
+   (newline)
+   (print-duck-text (caddr sec)))
+
+ (define (print-duck-unknown sec)
+   (print sec))
+
+ (define (print-module-duck mod)
+   (let loop ((mod mod))
+     (when (not (null? mod))
+       (when (car mod)
+	 (case (caar mod)
+	   ((MOD) (print-duck-module (car mod)))
+	   ((VAR) (print-duck-variable (car mod)))
+	   ((PAR) (print-duck-parameter (car mod)))
+	   ((FUN) (print-duck-procedure (car mod)))
+	   (else (print-duck-unknown (car mod)))))
+       (loop (cdr mod)))))
+
+ )
diff --git a/src/gendoc.scm b/src/gendoc.scm
new file mode 100644
index 0000000..e830ef8
--- /dev/null
+++ b/src/gendoc.scm
@@ -0,0 +1,4 @@
+
+(import duck-extract)
+
+(print "GENDOC")