diff --git a/scripts/singleuse.pl b/scripts/singleuse.pl
new file mode 100755
index 000000000..f26abff87
--- /dev/null
+++ b/scripts/singleuse.pl
@@ -0,0 +1,223 @@
+#!/usr/bin/perl
+#***************************************************************************
+#                                  _   _ ____  _
+#  Project                     ___| | | |  _ \| |
+#                             / __| | | | |_) | |
+#                            | (__| |_| |  _ <| |___
+#                             \___|\___/|_| \_\_____|
+#
+# Copyright (C) 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
+#
+# This software is licensed as described in the file COPYING, which
+# you should have received as part of this distribution. The terms
+# are also available at https://curl.haxx.se/docs/copyright.html.
+#
+# You may opt to use, copy, modify, merge, publish, distribute and/or sell
+# copies of the Software, and permit persons to whom the Software is
+# furnished to do so, under the terms of the COPYING file.
+#
+# This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+# KIND, either express or implied.
+#
+###########################################################################
+#
+# This script is aimed to help scan for and detect globally declared functions
+# that are not used from other source files.
+#
+# Use it like this:
+#
+# $ ./scripts/singleuse.pl lib/.libs/libcurl.a
+#
+# Be aware that it might cause false positives due to various build options.
+#
+
+my $file = $ARGV[0];
+
+my %wl = (
+    'Curl_none_cert_status_request' => 'multiple TLS backends',
+    'Curl_none_check_cxn' => 'multiple TLS backends',
+    'Curl_none_cleanup' => 'multiple TLS backends',
+    'Curl_none_close_all' => 'multiple TLS backends',
+    'Curl_none_data_pending' => 'multiple TLS backends',
+    'Curl_none_engines_list' => 'multiple TLS backends',
+    'Curl_none_init' => 'multiple TLS backends',
+    'Curl_none_md5sum' => 'multiple TLS backends',
+    'Curl_none_random' => 'multiple TLS backends',
+    'Curl_none_session_free' => 'multiple TLS backends',
+    'Curl_none_set_engine' => 'multiple TLS backends',
+    'Curl_none_set_engine_default' => 'multiple TLS backends',
+    'Curl_none_shutdown' => 'multiple TLS backends',
+    'Curl_multi_dump' => 'debug build only',
+    'Curl_parse_port' => 'UNITTEST',
+    'Curl_shuffle_addr' => 'UNITTEST',
+    'de_cleanup' => 'UNITTEST',
+    'doh_decode' => 'UNITTEST',
+    'doh_encode' => 'UNITTEST',
+    'Curl_auth_digest_get_pair' => 'by digest_sspi',
+    'curlx_uztoso' => 'cmdline tool use',
+    'curlx_uztoul' => 'by krb5_sspi',
+    'curlx_uitous' => 'by schannel',
+    'Curl_islower' => 'by curl_fnmatch',
+    'getaddressinfo' => 'UNITTEST',
+    );
+
+my %api = (
+    'curl_easy_cleanup' => 'API',
+    'curl_easy_duphandle' => 'API',
+    'curl_easy_escape' => 'API',
+    'curl_easy_getinfo' => 'API',
+    'curl_easy_init' => 'API',
+    'curl_easy_pause' => 'API',
+    'curl_easy_perform' => 'API',
+    'curl_easy_recv' => 'API',
+    'curl_easy_reset' => 'API',
+    'curl_easy_send' => 'API',
+    'curl_easy_setopt' => 'API',
+    'curl_easy_strerror' => 'API',
+    'curl_easy_unescape' => 'API',
+    'curl_easy_upkeep' => 'API',
+    'curl_escape' => 'API',
+    'curl_formadd' => 'API',
+    'curl_formfree' => 'API',
+    'curl_formget' => 'API',
+    'curl_free' => 'API',
+    'curl_getdate' => 'API',
+    'curl_getenv' => 'API',
+    'curl_global_cleanup' => 'API',
+    'curl_global_init' => 'API',
+    'curl_global_init_mem' => 'API',
+    'curl_global_sslset' => 'API',
+    'curl_maprintf' => 'API',
+    'curl_mfprintf' => 'API',
+    'curl_mime_addpart' => 'API',
+    'curl_mime_data' => 'API',
+    'curl_mime_data_cb' => 'API',
+    'curl_mime_encoder' => 'API',
+    'curl_mime_filedata' => 'API',
+    'curl_mime_filename' => 'API',
+    'curl_mime_free' => 'API',
+    'curl_mime_headers' => 'API',
+    'curl_mime_init' => 'API',
+    'curl_mime_name' => 'API',
+    'curl_mime_subparts' => 'API',
+    'curl_mime_type' => 'API',
+    'curl_mprintf' => 'API',
+    'curl_msnprintf' => 'API',
+    'curl_msprintf' => 'API',
+    'curl_multi_add_handle' => 'API',
+    'curl_multi_assign' => 'API',
+    'curl_multi_cleanup' => 'API',
+    'curl_multi_fdset' => 'API',
+    'curl_multi_info_read' => 'API',
+    'curl_multi_init' => 'API',
+    'curl_multi_perform' => 'API',
+    'curl_multi_remove_handle' => 'API',
+    'curl_multi_setopt' => 'API',
+    'curl_multi_socket' => 'API',
+    'curl_multi_socket_action' => 'API',
+    'curl_multi_socket_all' => 'API',
+    'curl_multi_strerror' => 'API',
+    'curl_multi_timeout' => 'API',
+    'curl_multi_wait' => 'API',
+    'curl_mvaprintf' => 'API',
+    'curl_mvfprintf' => 'API',
+    'curl_mvprintf' => 'API',
+    'curl_mvsnprintf' => 'API',
+    'curl_mvsprintf' => 'API',
+    'curl_pushheader_byname' => 'API',
+    'curl_pushheader_bynum' => 'API',
+    'curl_share_cleanup' => 'API',
+    'curl_share_init' => 'API',
+    'curl_share_setopt' => 'API',
+    'curl_share_strerror' => 'API',
+    'curl_slist_append' => 'API',
+    'curl_slist_free_all' => 'API',
+    'curl_strequal' => 'API',
+    'curl_strnequal' => 'API',
+    'curl_unescape' => 'API',
+    'curl_url' => 'API',
+    'curl_url_cleanup' => 'API',
+    'curl_url_dup' => 'API',
+    'curl_url_get' => 'API',
+    'curl_url_set' => 'API',
+    'curl_version' => 'API',
+    'curl_version_info' => 'API',
+
+    # the following funcions are provided globally in debug builds
+    'curl_easy_perform_ev' => 'debug-build',
+    'curl_memdebug' => 'debug-build',
+    'curl_memlimit' => 'debug-build',
+    'curl_memlog' => 'debug-build',
+    'curl_accept' => 'debug-build',
+    'curl_docalloc' => 'debug-build',
+    'curl_dofree' => 'debug-build',
+    'curl_domalloc' => 'debug-build',
+    'curl_dorealloc' => 'debug-build',
+    'curl_dorecv' => 'debug-build',
+    'curl_dosend' => 'debug-build',
+    'curl_dostrdup' => 'debug-build',
+    'curl_fclose' => 'debug-build',
+    'curl_fopen' => 'debug-build',
+    'curl_sclose' => 'debug-build',
+    'curl_socket' => 'debug-build',
+    'curl_socketpair' => 'debug-build',
+    );
+
+open(N, "nm $file|") ||
+    die;
+
+my %exist;
+my %uses;
+my $file;
+while (<N>) {
+    my $l = $_;
+    chomp $l;
+
+    if($l =~ /^([0-9a-z_-]+)\.o:/) {
+        $file = $1;
+    }
+    if($l =~ /^([0-9a-f]+) T (.*)/) {
+        my ($name)=($2);
+        #print "Define $name in $file\n";
+        $file =~ s/^libcurl_la-//;
+        $exist{$name} = $file;
+    }
+    elsif($l =~ /^                 U (.*)/) {
+        my ($name)=($1);
+        #print "Uses $name in $file\n";
+        $uses{$name} .= "$file, ";
+    }
+}
+close(N);
+
+my $err;
+for(sort keys %exist) {
+    #printf "%s is defined in %s, used by: %s\n", $_, $exist{$_}, $uses{$_};
+    if(!$uses{$_}) {
+        # this is a symbol with no "global" user
+        if($_ =~ /^curl_/) {
+            if(!$api{$_}) {
+                # not present in the API, or for debug-builds
+                print STDERR "Bad curl-prefix: $_\n";
+                $err++;
+            }
+        }
+        elsif($wl{$_}) {
+            #print "$_ is WL\n";
+        }
+        else {
+            printf "%s is defined in %s, but not used outside\n", $_, $exist{$_};
+            $err++;
+        }
+    }
+    elsif($_ =~ /^curl_/) {
+        # global prefix, make sure it is "blessed"
+        if(!$api{$_}) {
+            # not present in the API, or for debug-builds
+            print STDERR "Bad curl-prefix $_\n";
+            $err++;
+        }
+    }
+}
+
+exit $err;