--- title: "Flutter flutter_webrtc + AI Voice Agents (2026): Production Stack" description: "flutter_webrtc is the dominant cross-platform Flutter WebRTC plugin in 2026. Here is how AI voice agent apps build it with callkeep, FCM/PushKit, and pipecat_flutter." canonical: https://callsphere.ai/blog/vw4e-flutter-webrtc-ai-voice-agents-2026 category: "AI Voice Agents" tags: ["Flutter", "flutter_webrtc", "Voice AI", "Mobile", "Pipecat"] author: "CallSphere Team" published: 2026-03-25T00:00:00.000Z updated: 2026-05-07T16:13:34.642Z --- # Flutter flutter_webrtc + AI Voice Agents (2026): Production Stack > flutter_webrtc is the dominant cross-platform Flutter WebRTC plugin in 2026. Here is how AI voice agent apps build it with callkeep, FCM/PushKit, and pipecat_flutter. > Flutter has had production-grade WebRTC for years thanks to flutter_webrtc, and 2026 added pipecat_flutter, which wraps the streaming-LLM dance (STT → LLM → TTS) into one plugin. Combined with flutter-webrtc/callkeep, you can ship a cross-platform AI voice agent client in a single Dart codebase. ## Background flutter_webrtc is the official-by-convention Flutter WebRTC plugin (pub.dev: flutter_webrtc) and bridges to libwebrtc on iOS, Android, macOS, Windows, Linux, and the web. In April 2026, the Flutter WebRTC org also ships callkeep (CallKit + ConnectionService), and the broader ecosystem now includes pipecat_flutter 0.2.0, which abstracts the AI voice loop with sub-500 ms latency, transcript inspection, and mid-stream function calling. LiveKit and Stream both publish first-class Flutter SDKs that ride on flutter_webrtc. For AI voice agent apps, this means you can pick your level of abstraction: raw flutter_webrtc + your own signaling, LiveKit Flutter for media routing, or pipecat_flutter for the whole STT-LLM-TTS pipeline. ## Architecture ```mermaid flowchart LR Push[FCM / PushKit] --> Flutter[Flutter App] Flutter -- displayIncomingCall --> Callkeep[flutter-webrtc/callkeep] Callkeep -- answer --> Flutter Flutter -- getUserMedia --> WebRTC[flutter_webrtc RTCPeerConnection] WebRTC -- DTLS-SRTP --> Gateway[Pion Go gateway 1.23] Gateway -- NATS --> Pod[6-container agent pod] ``` ## CallSphere implementation We evaluate Flutter for cross-platform partner apps that need to embed our AI agents: - **Real Estate (OneRoof)** — Partner brokerages embed our Flutter SDK to add CallSphere voice agents inside their own apps. The signaling and media path is identical: Pion Go gateway 1.23 → NATS → 6-container pod (CRM, MLS, calendar, SMS, audit, transcript). See [/industries/real-estate](/industries/real-estate). - **Healthcare** — Healthcare partner apps use the OpenAI Realtime path with HIPAA-safe payloads. See [/industries/healthcare](/industries/healthcare) and [/lp/healthcare](/lp/healthcare). - **/demo browser path** — Same agents, plain Chrome. See [/demo](/demo). 37 agents · 90+ tools · 115+ DB tables · 6 verticals · HIPAA + SOC 2 · $149/$499/$1499 · 14-day [/trial](/trial) · 22% affiliate at [/affiliate](/affiliate). ## Build steps with code ```yaml # pubspec.yaml dependencies: flutter_webrtc: ^0.13.0 callkeep: ^0.4.0 firebase_messaging: ^15.0.0 ``` ```dart // lib/voice_call.dart import 'package:flutter_webrtc/flutter_webrtc.dart'; import 'package:callkeep/callkeep.dart'; final FlutterCallkeep _callkeep = FlutterCallkeep(); RTCPeerConnection? _pc; MediaStream? _localStream; Future setup() async { await _callkeep.setup(null, { 'ios': {'appName': 'CallSphere'}, 'android': { 'alertTitle': 'Permissions Required', 'alertDescription': 'For incoming calls', }, }); _callkeep.on(CallKeepPerformAnswerCallAction(), _onAnswer); } void _onAnswer(CallKeepPerformAnswerCallAction event) async { _localStream = await navigator.mediaDevices.getUserMedia({'audio': true}); _pc = await createPeerConnection({ 'iceServers': [{'urls': 'stun:stun.l.google.com:19302'}], }); _localStream!.getTracks().forEach((t) => _pc!.addTrack(t, _localStream!)); // Then negotiate offer/answer with backend } ``` ```dart // On FCM background message FirebaseMessaging.onBackgroundMessage((msg) async { await _callkeep.displayIncomingCall( msg.data['call_id']!, msg.data['from']!, ); }); ``` ## Pitfalls - **Forgetting iOS background modes** — `voip` and `audio` must be in Info.plist. - **Skipping minSdkVersion bump** — flutter_webrtc requires Android 24+; default Flutter projects are still 21. - **Using DownloadOnly Pod cache** — pod install must complete before `flutter run` on iOS. - **Web target nuances** — flutter_webrtc on web wraps the browser API; certain features (encoded transforms, Insertable Streams) are not yet uniform across mobile and web. - **Mismatching FCM background handler** — On iOS the FCM background message arrives via APNs, not VoIP push; you still need PushKit for the wake-from-killed case. ## FAQ **Does pipecat_flutter replace flutter_webrtc?** No — it sits on top, abstracting the STT/LLM/TTS pipeline. The transport is still WebRTC. **Can I use LiveKit instead?** Yes — LiveKit Flutter SDK is a more managed alternative if you want SFU-routed media and less signaling code. **Does it work on Flutter web?** Yes — flutter_webrtc has a web implementation; CallKit/Telecom does not apply on web. **How is the binary size?** ~7 MB on iOS, ~9 MB on Android. **Is the New Architecture (Impeller) supported?** Yes since flutter_webrtc 0.10.x. ## Sources - [https://pub.dev/packages/flutter_webrtc](https://pub.dev/packages/flutter_webrtc) - [https://github.com/flutter-webrtc/callkeep](https://github.com/flutter-webrtc/callkeep) - [https://medium.com/@tri.dev.dhm/building-real-time-voice-ai-agents-in-flutter-with-pipecat-6abbc6d223f0](https://medium.com/@tri.dev.dhm/building-real-time-voice-ai-agents-in-flutter-with-pipecat-6abbc6d223f0) - [https://getstream.io/video/sdk/flutter/tutorial/ai-voice-assistant/](https://getstream.io/video/sdk/flutter/tutorial/ai-voice-assistant/) - [https://github.com/livekit/agents](https://github.com/livekit/agents) Try CallSphere voice agents at [/demo](/demo), see [/pricing](/pricing), or start a [/trial](/trial). --- Source: https://callsphere.ai/blog/vw4e-flutter-webrtc-ai-voice-agents-2026