I built this app that allows hikers to generate their own custom mileage tables and elevation profiles for any section of the AT (NOBO or SOBO).

https://bentwells.shinyapps.io/atdata/

It's not nearly as fancy as Guthooks, but it's free. The data are based on the 2018 edition of WhiteBlaze pages. I worked with the author, Rick, to make sure everything is accurate as possible.

It doesn't have any town/service info, so it's not meant to replace the guide book - but you can export the mileage tables and elevation profiles to a PDF and print it to save weight.

Disclaimer: I am currently using a free service to host the app. The free service limits each app to 25 hours of user time per month. After that it gets shut down for the rest of the month. I would have to use their paid service to get more user time. So if you like this app, please consider donating so more people can use it.