Custom timeframes option would be a good and helpful features as other softwares such as TradingView, AmiBroker etc provide it for free.
Stockalyze already has that. You actually meant zoom instead of timeframe (in stockalyze terminology :).
Look at the toolbar that contains tool names like 3M, 6M, 1Y, etc. in the chart window. They are in the left of the center.
Please try it and let me know if you don't find that.
Regards,
Sacha