Probably a wasm port of tesseract. E.g https://robertknight.github.io/tesseract-wasm/ https://robertknight.github.io/tesseract-wasm/ Note that I haven't tried

Probably a wasm port of tesseract. E.g https://robertknight.github.io/tesseract-wasm/ https://robertknight.github.io/tesseract-wasm/ Note that I haven't tried any of them, but tesseract is still likely the leading open source OCR that works with CPU.