Tesseract.js Core (WebAssembly builds)

Prebuilt, CDN‑ready Tesseract.js core WebAssembly bundles for browser and Node. Use these files directly without compiling Tesseract yourself.

What’s here

• WebAssembly builds and JS wrappers: baseline, SIMD, LSTM, and SIMD+LSTM variants.
• A minified worker script compatible with tesseract.js.
• Static hosting‑friendly headers for secure CDN usage.

Files

• tesseract-core.wasm.js, tesseract-core.wasm
• tesseract-core-simd.wasm.js, tesseract-core-simd.wasm
• tesseract-core-lstm.wasm.js, tesseract-core-lstm.wasm
• tesseract-core-simd-lstm.wasm.js, tesseract-core-simd-lstm.wasm
• tesseract-worker.min.js

Quick Start — Browser (CDN)

import Tesseract from 'tesseract.js';

const worker = await Tesseract.createWorker({
  corePath: 'https://tesseract.ocrmd.com/tesseract-core-simd.wasm.js',
  workerPath: 'https://tesseract.ocrmd.com/tesseract-worker.min.js',
});

await worker.load();
await worker.loadLanguage('eng');
await worker.initialize('eng');
const { data: { text } } = await worker.recognize(imageElementOrBlobOrUrl);
await worker.terminate();

Quick Start — Node (npm)

npm i tesseract.js tesseract.js-core

const Tesseract = require('tesseract.js');

const worker = await Tesseract.createWorker({
  corePath: require.resolve('tesseract.js-core/tesseract-core-simd.wasm.js'),
});

await worker.load();
await worker.loadLanguage('eng');
await worker.initialize('eng');
const { data: { text } } = await worker.recognize('/path/to/image.png');
await worker.terminate();

Build Variants

• tesseract-core.wasm.js — baseline WebAssembly build.
• tesseract-core-simd.wasm.js — SIMD‑optimized; fastest where supported.
• tesseract-core-lstm.wasm.js — accuracy‑focused LSTM build.
• tesseract-core-simd-lstm.wasm.js — best accuracy + speed; requires SIMD support.

Recommendation: prefer *-simd.wasm.js in modern browsers. Feature‑detect SIMD and fall back to baseline when unavailable.

Compatibility & Requirements

• WebAssembly required; asm.js fallback is not provided in this distribution.
• Works best with tesseract.js v5+.
• SIMD support varies by browser/CPU.

Hosting, CORS & CSP

When using files from https://tesseract.ocrmd.com, response headers enforce strict security policies:

• CORS allows https://ocrmd.com.
• CSP restricts worker-src, script-src, connect-src, etc. Ensure your app’s CSP permits loading the worker and WASM from your chosen origin.

Troubleshooting

• 404 or TypeError: WebAssembly: use the *.wasm.js wrapper, not the raw *.wasm.
• CORS/CSP errors: align your site’s CSP with hosting policies.
• Empty OCR results: verify language initialization and image quality.

License & Credits

• License: Apache‑2.0 (see LICENSE.txt).
• Upstream source: https://github.com/naptha/tesseract.js-core