Why is on-device OCR a big deal?
OCR is where most tools paywall or upload: your scans (often the most sensitive documents you have) get processed on someone's server. Here Tesseract runs as WebAssembly in your browser, so the document never leaves your machine. Safety limits adapt to the device to prevent tab crashes.
How accurate is it?
Treat the output as a first draft, not a finished transcript. Pages are read at about 144 dpi regardless of how finely you scanned them, and on real-world documents some words are missed even when the scan looks clean, always read the result against the original before relying on it. Clear, high-contrast printed text does best; handwriting, low-resolution photos and heavy skew do worst. The tool skips words it is not reasonably confident about rather than inventing text.