I used and enjoyed circuitlab.io until it went for-pay only. Nice to have an easy to use free alternative for very casual hobbyists like me.
That would be https://www.circuitlab.com/ -- I built it :) Edit: if anyone wants, reply with your CircuitLab username and I'll give you a free membership upgrade when I get home this evening.
Thank you for the offer, even if you don’t get to me.