Periplus

Periplus starts from a prompt: type a topic, ask a question or drop in a PDF, and it generates a full course with chapters that build on one another. Lessons link to related documents, so you can open two side by side or follow a graph of connected ideas. Every lesson can branch into a new course, letting you drill into a detail without losing your place. Anything you open is stored in a personal library that is searchable and resumable, and new courses can pick up where your existing knowledge ends.

Learning support is built into the flow rather than bolted on. Each lesson can convert into flashcards and quizzes, which resurface on a spaced schedule timed to appear just before you would forget. Courses can also be turned into podcast episodes: two AI hosts walk through the chapters, captions follow the audio word by word, and you can raise your hand to ask a question mid-episode. Lessons can include maps, diagrams and worked math. On the Premium tier, deep research pulls in web sources you can open yourself, and PDF-based courses build the curriculum around your own material.

Periplus is explicit about its difference from ChatGPT: instead of you deciding what to study next, the platform lays out the curriculum, tests you as you go, and guards against hallucinated content by checking lessons before they are shown. It supports multiple languages, chosen at signup or changed in settings, and generates everything in the selection. There is a free plan with no credit card required for creating courses and taking quizzes.