Do I need to install an app to make international calls?

No.

PuchiDen runs entirely in your web browser — no app, no SIM, no plug-in, no download.

It works on Windows, macOS, Linux, ChromeOS, iOS, and Android, so you can sign in from any device with a microphone and a stable internet connection. Open the page, log in, dial — that is the whole flow.

P.S: Although still possible, browsers on mobile are inherently unstable for calls. Read our FAQ about it here.