In 2020, we recommend TimelineJS by Northwestern University's KnightLab.
From their website:
TimelineJS is an open-source tool that enables anyone to build visually rich, interactive timelines. Beginners can create a timeline using nothing more than a Google spreadsheet. Experts can use their JSON skills to create custom installations, while keeping TimelineJS's core functionality.
The video below is a quick demonstration of making a timeline with TimelineJS.