React rich text editor with built-in spellcheck

Why this is unusual

Most React rich text editors treat spellcheck as somebody else's job. You get formatting, lists and links, and then you either accept the browser's native checker — which you cannot style, position or control, and which disappears the moment you set contenteditable to a custom implementation — or you bolt on a paid service that sends every keystroke to someone's server.

Sqwig ships the dictionary. A SymSpell engine compiled to WebAssembly runs in a Web Worker beside your editor, checks as the user types, and renders its own underlines and suggestion popover. Nothing is transmitted, so there is no request to fail, no latency to hide, and nothing to put in a DPA.

Install

npm i @sqwig/core @sqwig/react

Then copy the three runtime assets into a statically served folder — the WASM engine, its worker, and the dictionary chunks. A bundler cannot inline them because they are fetched at runtime:

cp -r node_modules/@sqwig/core/dist public/sqwig

Full detail in the quickstart.

Basic usage

<SqwigEditor> is a thin, uncontrolled wrapper. Core options are props, read once at mount. It is StrictMode-safe.

import { useMemo, useRef } from "react";
import { SqwigEditor } from "@sqwig/react";
import { createSpellChecker, type Editor } from "@sqwig/core";

export function Compose() {
  const editor = useRef<Editor>(null);

  // Create ONCE. Inline in JSX spawns a Worker on every render.
  const spell = useMemo(() => createSpellChecker({ assetBaseUrl: "/sqwig/" }), []);

  return (
    <SqwigEditor
      ref={editor}
      spell={spell}
      license="free"
      placeholder="Say something…"
      onChange={(html) => save(html)}
    />
  );
}

That useMemo is the single most important line on this page. The spellchecker owns a Web Worker and a WASM instance; creating it inline in JSX creates a new one on every render, and you will watch your tab's memory climb.

Props

SqwigEditorProps extends EditorOptions, so every core option is available as a prop. These are the React-specific additions:

The most commonly used inherited options:

Every option is in the full options table.

The ref is the editor

The wrapper forwards a ref to the complete core Editor instance — not a subset, and not a React-flavoured shim. Anything the core can do, you can do:

const editor = useRef<Editor>(null);

// later
editor.current?.getHTML();
editor.current?.setHTML("<p>Replaced</p>");
editor.current?.focus();

See editor methods and events.

Why it is uncontrolled

There is no value prop, and that is deliberate. A controlled rich text editor has to reconcile a React render against a live DOM selection on every keystroke, and the usual result is a cursor that jumps to the end of the document mid-word. Sqwig keeps the document in the editor and hands you HTML through onChange.

In practice: hold the HTML in state if you need it for a save button, but do not feed it back in as a prop. To replace content programmatically, call setHTML on the ref.

Vite

Copy the assets into public/sqwig/ and point at them with a root-relative path. Vite serves public/ at the root in both dev and build, so /sqwig/ works in each without conditionals:

cp -r node_modules/@sqwig/core/dist public/sqwig

Do not import the worker or the .wasm. Vite would try to fingerprint and rewrite them, and the runtime fetch then misses.

Next.js and server rendering

The editor needs a real DOM, a Web Worker and WebAssembly, so it is client-only. In the App Router, mark the component "use client" and, if you are rendering it inside a server-rendered route, load it without SSR:

const Compose = dynamic(() => import("./Compose"), { ssr: false });

Assets go in public/sqwig/, same as Vite.

Common pitfalls

A new Worker on every render

Creating the spellchecker inline in JSX. Wrap it in useMemo with an empty dependency array, as above.

Changing a prop and nothing happening

Options are read at mount. Changing placeholder or toolbar later will not re-initialise the editor — use the ref for runtime changes.

Underlines never appear

The editor mounted but the assets 404'd. Check the Network panel for spell.worker.js, spell_wasm_bg.wasm and dict/. The editor deliberately keeps working without them, so this fails quietly.

Double mounts in development

StrictMode mounts twice on purpose. The wrapper handles it — if you see two editors, something outside the wrapper is duplicating the element.

Where to go next

• Quickstart — installation, assets, the license option
• createEditor options — the full table
• Styling and theming — CSS custom properties
• Spellcheck and suggestions — how checking behaves
• Privacy — what the component transmits, which is nothing