The best alternatives to Instant Update are Grid.js, Berowra, and PageKit. If these 3 options don't work for you, we've listed a few more alternatives below.
Grid.js is a Free and open-source HTML table plugin written in TypeScript. It works with most JavaScript frameworks, including React, Angular.js, Vue and VanillaJs.
Berowra is an open source CMS for hobbyists and small buisnesses that enables them to start building on top of their content in just three minutes. It comes with an API, file hosting, Markdown support and more! At the moment it's in beta on Deta Space!
ContentBuilder.js is a Jquery plugin that allows users to write anything beautifully with drag & drop content blocks. A Jquery plugin that converts DIV element into editable area. Unlike classic editors, the plugin provides you with beautifully designed content blocks, ready to drag & drop.