Glimmer - Fast and light-weight UI components for the web
Delighted - The fastest and easiest way to gather actionable feedback from your customers
Preact.js - Preact is a fast 3kB alternative to React with the same modern API. Components & Virtual DOM.
UserTesting.com - Usability testing has never been easier. Get videos of real people speaking their thoughts as they use websites, mobile apps, prototypes and more!
Svelte - Cybernetically enhanced web apps
Promoter.io - Promoter is designed to capture actionable and accurate customer feedback that reduces churn and drives growth