I've mostly used StudioTax, which is a client run locally: in the past it's been donation-supported, but starting this year you will have to pay CA$ 15 to upload your data. The 2020 version is currently available (but not yet officially certified). It allows you to log into your CRA account and fetch all the available T3/4/5 data that has been uploaded by financial institutions.
As noted, SimpleTax can mine your data where previously (pre-WS) it did not.
A list of NETFILE-certified software is available from the CRA, though as I type this it has not been updated for the 2020 tax year yet:
* https://www.canada.ca/en/revenue-agency/services/e-services/...
I've mostly used StudioTax, which is a client run locally: in the past it's been donation-supported, but starting this year you will have to pay CA$ 15 to upload your data. The 2020 version is currently available (but not yet officially certified). It allows you to log into your CRA account and fetch all the available T3/4/5 data that has been uploaded by financial institutions.