Online Clipboard
Share a Wi-Fi password with another device
Twenty-six random characters on a sticker behind the router, and a television remote with an on-screen keyboard.
What the phones can do on their own
Android has offered a QR code for the network you are connected to for years: open the Wi-Fi settings, choose the network, and share. Another Android phone scans it and joins.
iPhones can pass a password to a nearby iPhone, iPad or Mac automatically when both have each other in their contacts and are unlocked and close by.
Both are excellent, and both only cover the case where the two devices come from the same family.
The cases they do not cover
A smart TV, a games console, a printer, a laptop running a different system, a guest whose phone is not the same brand as yours. In all of these you end up reading characters out loud, and a long password is exactly where that goes wrong — one wrong character and the device just says it failed, without telling you which one.
Hand it over as pasteable text
Open Online Clipboard, paste the password into a board, and show the QR code to the other device — or send the link. The password arrives as text that can be copied with one tap and pasted into the network dialog, with no chance of a misread character.
Because a board also takes files, this is the same route you would use for the manual of the router or a photo of the sticker.
One thing worth saying plainly: a board link is a key. Whoever holds it can open the board. Share it deliberately, and remember that everything in it is deleted automatically after seven days — which for a password you just handed to a guest is usually exactly what you want.
In short: Between two phones of the same family, use the built-in QR sharing. For everything else — a TV, a laptop, a guest on another system — hand the password over as text you can paste.