I would recommend Kinto. It&#x27;s open source and used in production for mozilla browser sync service.<p><a href="https:&#x2F;&#x2F;github.com&#x2F;Kinto&#x2F;kinto" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;Kinto&#x2F;kinto</a>