TimelineJS
https://timeline.knightlab.com/
Open‑source, Google‑spreadsheet‑based tool for building rich, media‑enhanced interactive timelines accessible to beginners and advanced users alike.
Tiki‑Toki Timeline Maker
Web‑based timeline maker offering beautiful interactive 2D and 3D timelines, multimedia events and embedding support—popular for storytelling and education.
Time.Graphics
Free (with optional premium) online timeline maker suited for educational and business uses—allows comparison of historical data and Gantt‑style planning.
ChronoZoom
Free, open‑source, Big History time visualizer from cosmic to modern eras—visualizes vast time scales in a zoomable interface: Big Bang to present.
HistoryTimeline.com
https://www.historytimeline.com/
Interactive timeline software for historians—browse and create timelines across eras with access to primary sources and encyclopedia links.
Sutori
Browser‑based multimedia timeline creation tool—supporting quizzes, images, video, audio and collaborative editing, widely used in education.
History Commons
https://www.historycommons.org/
Open‑content platform offering dynamic context timelines: scalable event search and interconnected historical summaries contributed and peer‑reviewed.