Thanks are due to the following

* Serge Zaitsev <zaitsev.serge@gmail.com>

for jsmn, the world's fastest JSON parser/tokenizer.

* The authors of libsodium <https://libsodium.org>

for the base64 encoding/decoding routines.

* Marc Alexander Lehmann <libev@schmorp.de>

for libev <http://libev.schmorp.de>

* Marian Vittek

for SGLIB <http://www.xref-tech.com/sglib)

* Michel Stam <michel@reverze.net>

for the nsupdate.sh DNS-01 challenge hook script

* The authors of libcurl <https://curl.haxx.se/libcurl>

* The authors of GnuTLS <https://gnutls.org>

* The authors of OpenSSL <https://www.openssl.org>

* The authors of mbedTLS <https://tls.mbed.org>

(this list may not be complete, if you think something is missing

please submit a pull request!)