Zoiper is a widely‑used soft‑phone for SIP‑based calling. The list below gathers 20 **free** VoIP applications—both dedicated SIP clients and general‑purpose voice‑chat tools—that can replace Zoiper on desktop, mobile, or web platforms.
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Open‑source SIP softphone for Windows, macOS, Linux, iOS and Android with HD audio, video, and encryption.
Web‑based, zero‑install conference platform supporting SIP integration, screen sharing, and end‑to‑end encryption.
Lightweight Windows SIP client focused on high‑quality audio, low latency, and simple UI.
Free, open‑source softphone for Linux and Windows offering SIP/ H.323 support and video calling.
Free Windows softphone from 3CX, compatible with any SIP account and featuring call‑recording and presence.
Simple Windows SIP client with support for multiple accounts, codecs, and call‑transfer features.
Free iOS/Android SIP softphone from Grandstream, offering HD voice, push‑notifications, and multiple account handling.
Cross‑platform SIP client with a free tier that includes basic calling, push notifications, and TLS/SRTP encryption.
Android‑only open‑source SIP client offering extensive codec support and integration with Android's call UI.
Android SIP client with a clean interface, multiple account support, and built‑in call‑recording.
Open‑source Linux softphone with a modern UI, SIP and XMPP support, and end‑to‑end encryption.
Low‑latency, open‑source voice chat primarily for gamers; works over encrypted UDP and can be self‑hosted.
Free (non‑commercial) voice communication tool with high‑quality audio, server‑side control, and optional encryption.
Popular free platform for voice, video, and text chat; offers server‑based rooms and screen sharing.
Free messaging app that includes high‑definition voice calls over the internet, with end‑to‑end encryption.
Widely‑used mobile messenger offering free voice (and video) calls over data connections.
Privacy‑focused messenger providing encrypted voice and video calls, all free of charge.
Cloud‑based messaging app with free voice calls, group calls, and optional end‑to‑end encrypted secret chats.