Baicizhan gives every word a scene to hang on: a still from a series, an example sentence, four different review exercises and a schedule counted backwards from the exam date. Core features are free and progress syncs across devices.

Duolingo breaks language study into lessons of a few minutes, with instant feedback, a streak counter and a leaderboard. More than forty languages, the whole course free to use, progress synced between web and phone, and conversation practice on the paid tier.

A non-profit learning service that costs nothing to use. Courses run from preschool numeracy to early university mathematics, science, grammar, history and financial literacy, with practice built around mastery and dashboards for parents and teachers. More than fifty languages, no advertising.

One prompt box asks how it can help with your research, five starters sit beneath it, and behind them a chain of tools: search in three depths, a review with a published benchmark, chat over a PDF, drafting, diagrams, citations and a detector.

Moyu Danci is a vocabulary tool for people who study in the gaps of a working day: a word window that fades into the background, a key that hides it, and a review schedule that decides what comes back and when.