you could use Macromedia Flash. Which is the old version of Adobe Animate CC.I love Macromedia Flash 8.
It's a bit old (over ten years now Jesus lord) but I love it so much.
ToonBoom is also a great tool but I could never get into it since I have used Flash for so long lol
I think adobe flash cs3 is free to download somewhere too, which I think is newerAdobe Animate CC is pretty good. Or as suggested here
you could use Macromedia Flash. Which is the old version of Adobe Animate CC.