I use
World Nomads Travel Insurance.
They send you a receipt email confirming your purchase of coverage and your travel insurance members’ log-in details. All of your policy documentation is permanently available online. You to access any time you need it.
I've also purchased a policy after already leaving for my destination once I decided I would need it. Thats pretty nice since most travel insurance require you to purchase it before leaving your country of residence.
Happy Travels!