The official Retsly PHP SDK by Retsly calls the Retsly API which provides access to Retsly's real state backend. It can be used to build robust realtime applications without a database. It requires PHP 5.4+.
The hot new thing in the mobile world is Progressive Web Apps (PWAs) and it’s possible they might spell the end for the humble native mobile app. Google has just effectively green-lighted PWAs to be the future of Android. Mobile expert Henrik Joreteg over at his blog explains.
In a world of monolithic web frameworks, Express.js offers an alternative. It is described as a "fast, unopinionated, minimalist server-side web framework for Node.js." and strives to make web application development for Node.js easier. This article breaks down exactly how Express works.