> For AI agents: the complete documentation index is available at https://open-spaced-repetition.github.io/ts-fsrs/llms.txt, the full documentation bundle is available at https://open-spaced-repetition.github.io/ts-fsrs/llms-full.txt.

# ts-fsrs

Fully customisable spaced repetition.

> A type-safe scheduler framework for TypeScript. Start with FSRS-7, then choose your models, clocks, and middleware without changing API families.

[Get started](/guide/) | [Open the playground](/playground)

## Features

- **Type-safe by construction**: Schemas drive runtime validation and the inferred input and output types at the same time.
- **Customize your algorithm without having to migrate**: Start with the default scheduler, then replace models, clocks, and policies on the same core.
- **Lazy by design**: Lazy previews, version-based code splitting, and tree-shakable subpath exports.