Image captchas/OCR basic machine learning

I need to automate the process of solving the captchas like and including the ones in the txt file. Script input must be in base64 value like in the txt file and output must be the letters/numbers that are in the picture. Preferably the solve rate will be 80~%+ and include a basic machine learning model so the rate will eventually go up, however this is desirable. Language preference is Python as i plan to eventually wrap it in a flask app, however GO will work if you find a more efficient solution. Any other details needed let me know, quite flexible on time.