Below are the 7 official tests released by ACT over the years in electronic format. The answer key is at the back of each document.
When attempting these tests, start with the most recent one and work your way back in time.
Math: Note that the Math section has gotten progressively more difficult over the years, so the 2021-2022 test is a better representation of today's Math section than any of its predecessors.
Reading: Another recent development is that the Reading section now has a paired passage; this appears only in the three most recent tests (2021-2022, 2018-2019, and 2015-2016).