As others have mentioned, Transkribus works pretty well for handwritten text recognition. You can also train your own model if you have enough source material.
If the documents you have are able to be made public, you could upload them to Wikimedia Commons and use https://ocr.wmcloud.org/ — you can use Transkribus via that. (Disclosure: I'm an engineer working on the Wikimedia OCR project.)
If the documents you have are able to be made public, you could upload them to Wikimedia Commons and use https://ocr.wmcloud.org/ — you can use Transkribus via that. (Disclosure: I'm an engineer working on the Wikimedia OCR project.)