udpipe-wasm

Browser-local dependency parsing. UDPipe compiled to WebAssembly: tokenize, tag, and parse text into a Universal Dependencies tree — no server, no network at parse time.

• Tiny: ~210 kB package (wasm + glue); single-digit-millisecond parses.
• Real syntax: full dependency tree (nsubj, root, obj, …), not just POS tags.
• Bring-your-own-model: the parser ships without a model (see below).

Install

npm install udpipe-wasm

Bring your own model

The model is not bundled. The UD 2.5 models are CC BY-NC-SA, so bundling one would impose that licence on every consumer. Download a model and host it yourself:

curl -L -o english-ewt.udpipe \
  https://raw.githubusercontent.com/jwijffels/udpipe.models.ud.2.5/master/inst/udpipe-ud-2.5-191206/english-ewt-ud-2.5-191206.udpipe

Serve it as a static asset (e.g. /models/english-ewt.udpipe).

Usage

import { loadParser } from "udpipe-wasm";

const parser = await loadParser({ modelUrl: "/models/english-ewt.udpipe" });
const tree = parser.parse("I hate my job.");

tree.root();          // { form: "hate", deprel: "root", head: 0, ... }
tree.children(2);     // direct dependents of token 2
tree.tokens.find((t) => t.deprel === "nsubj"); // { form: "I", ... }

loadParser fetches the wasm + model once (singleton) and rejects on failure. parse() runs on the main thread (single-digit ms for short sentences) and returns an empty-token tree for blank input rather than throwing.

API

function loadParser(opts: { modelUrl: string; wasmUrl?: string }): Promise<Parser>;

interface Parser {
  parse(text: string): DependencyTree;
}

interface UDToken {
  id: number; form: string; lemma: string;
  upos: string; head: number; deprel: string;
}

interface DependencyTree {
  tokens: UDToken[];
  root(): UDToken | null;          // the deprel === "root" token
  children(id: number): UDToken[]; // tokens whose head === id
}

parseConllu(conllu: string): DependencyTree is also exported, if you already have CoNLL-U from elsewhere.

Building from source

See build/README.md. npm run build clones pinned UDPipe v1.3.1, compiles it with Emscripten (-Oz -std=c++17), and emits the wasm + glue into dist/.

License

MPL-2.0 (matching UDPipe). Models are licensed separately by their providers.