Everything in the catalog

Builds a Mongoose schema definition from sample JSON.

Generates React PropTypes declarations from a JSON sample.

Generates Rust structs with serde derive attributes from JSON.

Generates Scala case classes from a JSON sample.

Generates a Zod validation schema from sample JSON.

Compacts a JSON-LD document against a context.

Expands a JSON-LD document so all terms are full IRIs.

Flattens a JSON-LD graph into a single level of nodes.

Serialises JSON-LD as RDF N-Quads.

Computes Keccak-256 hashes, the variant used by Ethereum, from text in several encodings.

Web chemical structure editor that exports MOL, SMILES and other formats.

Free analysis board with engine evaluation for any position or imported game.

Set up any chess position by placing pieces, then analyse or share it.

Browse chess openings and how they are played in games on the site.

Guided chess lessons that practise common positions such as basic checkmates.

Race other players or friends through a shared set of chess puzzles.

Timed run where you solve as many chess puzzles as you can in a few minutes.

Tactics trainer that serves puzzles and tracks your puzzle rating.

Calendar where you click to add, drag and copy events, saved in the URL so it can be shared.

Converts Markdown to HTML in a side-by-side playground.

Interactive demo of how model complexity trades bias against variance.

Animated explanation of k-fold cross-validation and why it is used.

Step-by-step interactive explanation of how a decision tree picks its splits.

Scroll-driven visual essay on fitting a line, loss, and gradient-based training.