diff --git a/toolbox/dynarray.c b/toolbox/dynarray.c
new file mode 100644
index 0000000..e9b7b03
--- /dev/null
+++ b/toolbox/dynarray.c
@@ -0,0 +1,103 @@
+#include "dynarray.h"
+#include <stdlib.h>
+#include <limits.h>
+
+void
+dynarray_init( dynarray_t *a )
+{
+    a->count = a->capacity = 0;
+    a->items = NULL;
+}
+
+
+static void
+dynarray_reserve_more( dynarray_t *a, int count )
+{
+    int old_cap = a->capacity;
+    int new_cap = old_cap;
+    const int max_cap = INT_MAX/sizeof(void*);
+    void** new_items;
+    int new_count = a->count + count;
+
+    if (count <= 0)
+        return;
+
+    if (count > max_cap - a->count)
+        abort();
+
+    new_count = a->count + count;
+
+    while (new_cap < new_count) {
+        old_cap = new_cap;
+        new_cap += (new_cap >> 2) + 4;
+        if (new_cap < old_cap || new_cap > max_cap) {
+            new_cap = max_cap;
+        }
+    }
+    new_items = realloc(a->items, new_cap*sizeof(void*));
+    if (new_items == NULL)
+        abort();
+
+    a->items = new_items;
+    a->capacity = new_cap;
+}
+
+void
+dynarray_append( dynarray_t *a, void* item )
+{
+    if (a->count >= a->capacity)
+        dynarray_reserve_more(a, 1);
+
+    a->items[a->count++] = item;
+}
+
+void
+dynarray_done( dynarray_t *a )
+{
+    free(a->items);
+    a->items = NULL;
+    a->count = a->capacity = 0;
+}
+
+// string arrays
+
+void strlist_init( strlist_t *list )
+{
+    dynarray_init(list);
+}
+
+void strlist_append_b( strlist_t *list, const void* str, size_t  slen )
+{
+    char *copy = malloc(slen+1);
+    memcpy(copy, str, slen);
+    copy[slen] = '\0';
+    dynarray_append(list, copy);
+}
+
+void strlist_append_dup( strlist_t *list, const char *str)
+{
+    strlist_append_b(list, str, strlen(str));
+}
+
+void strlist_done( strlist_t *list )
+{
+    STRLIST_FOREACH(list, string, free(string));
+    dynarray_done(list);
+}
+
+static int strlist_compare_strings(const void* a, const void* b)
+{
+    const char *sa = *(const char **)a;
+    const char *sb = *(const char **)b;
+    return strcmp(sa, sb);
+}
+
+void strlist_sort( strlist_t *list )
+{
+    if (list->count > 0) {
+        qsort(list->items,
+              (size_t)list->count,
+              sizeof(void*),
+              strlist_compare_strings);
+    }
+}