Overview

What Schrollar is

Schrollar teaches hard ideas in small pieces. Each idea is a box with up to five layers:

Boxes belong to topics, and topics to worlds: Graphs, Algebra, Strings, Data Structures, Dynamic Programming, How AI Thinks, Speed and GPUs, and Music Theory. Boxes declare what they build on, so the app can order them, warn you when you skip ahead, and draw maps.

The learner loop

flowchart LR
  F[Feed<br/>planner picks the next boxes] --> B[Open a box]
  B --> D[Go deeper<br/>Why → How → Code → Try]
  D --> K{Worth remembering?}
  K -- Keep --> R[Review card<br/>FSRS schedule]
  K -- Move on --> F
  D -- confident and wrong --> R
  R -- due --> RV[Review: recall, then rate]
  RV --> R
  RV --> F

Around that loop: daily puzzles with shareable challenge links, search and exploration by world and topic, decks, maps of every topic, reminders, captions in English and Hinglish (Hindi in Latin script), and an account that syncs across devices.

Design principles

1. Offline first. Every action is written to the device first and synced later. The app works on a train with no signal, and nothing a learner does is lost to a bad connection.
2. Content is data, not code. Lessons, interactive parameters, release notes and remote switches ship as signed content. A new lesson never waits for an app store review.
3. One codebase, three platforms. The same React app runs as a website and inside native shells on iOS and Android.
4. Decide transparently. Every choice the app makes for a learner (what to show next, what to review) goes through a named policy and is logged with its alternatives and reasons, so it can be evaluated and improved.
5. Pseudonymous by default. Analytics never carry account identifiers, typed text is scrubbed before it leaves the database, and research use needs explicit consent.
6. Boring infrastructure. Postgres as the system of record, a modular monolith for the API, managed edge and storage. Few moving parts, each well understood.

The system at a glance

The codebase

A pnpm and Turborepo monorepo:

${sch.nav()}