How it works
Does the person I write to need to install anything?
No. The letter is a link. It opens in any browser, complete, and stays there. No app, no account, nothing to sign up for.
Can Instar read my letter?
No. Your browser encrypts the letter with AES-GCM-256 before anything is sent. The key rides in the link after the #, which browsers never send to a server. Instar stores ciphertext and one timestamp: when the letter may open.
Can they peek before it lands?
No. The server refuses to hand over the letter before its opening time. Until then there is nothing on the page to peek at.
How fast do the couriers fly?
At their real, measured speeds. Jakarta to Amsterdam by green darner, the fastest insect reliably clocked, takes about eight days. A dung beetle takes years. Every speed is cited on the couriers page.
What is the public sky?
An opt-in map of letters in flight. It shows city to city and the courier. Never the names, never the words.
How long does a letter stay?
Thirty days after it opens, then it is deleted. Print it to keep it. Either side can delete it early.