GPT-Live vs Realtime vs Gemini Live: what differs?

First choose between using an app and building one

Gemini Live is a ready-to-use conversation feature in Google's app. Gemini Live API, GPT-Live and OpenAI Realtime are developer interfaces for building experiences. Comparing them without that distinction can lead to the wrong purchase or architecture.

This guide compares documented roles. It is not a measured voice-quality or latency ranking.

Sources: OpenAI architecture guide, Realtime guide, Gemini Live help and Gemini Live API.

GPT-Live: keep conversation and backend work separate

GPT-Live supports simultaneous listening and speaking while delegated work runs elsewhere. You can use Responses delegation or connect your own backend through client delegation. The app retains responsibility for permissions and business actions. GPT-Live documentation.

This is a candidate when you already have a useful text-based workflow and want a voice interface around it. Separate the instruction for how the assistant speaks from the instruction for what the business process must do. A friendly voice should never count as evidence that an order update succeeded.

Realtime: one session for speech and tools

The Realtime API works directly with audio, keeps conversation state and can call tools. Its documentation covers interruption handling and browser/server connections. Realtime documentation.

An existing Realtime application may already satisfy your needs. Test the actual weakness before changing architecture: missed interruptions, incorrect entities, long waits or failed tool actions. Switching platforms does not automatically solve a poorly defined workflow.

Gemini Live: app experience versus API

Google's consumer help describes spoken conversation, interruption, camera and screen-sharing options, with rollout and device conditions. The linked instructions cover Android; use Google's device-specific guidance for other platforms. Gemini Live help.

The developer Live API instead provides a streaming interface for audio, images and text. Its overview describes stateful WebSockets and recommends ephemeral tokens rather than standard API keys for direct production client connections. Live API overview.

For a creator who wants to practise an interview or discuss an idea aloud, start with an available app. For a business that needs its own interface and data connections, evaluate the API and the full implementation effort.

Follow one request through the architectures

Consider an illustrative voice assistant for a creator's production calendar. The user says, “Find the review call with Maya and move it to Friday afternoon.” While the calendar lookup runs, they add, “Actually, don't move it; just tell me the time.” The successful result is the correct existing appointment time with no calendar change.

With GPT-Live, the speaking layer delegates the lookup to a backend that knows calendar permissions and time-zone rules. The spoken correction can arrive while that work continues. Your application must communicate the changed intent to the backend or discard an obsolete proposed update. Full-duplex conversation means the user can be heard while the assistant speaks; it does not make an already-started business action disappear. GPT-Live's delegation model.

With Realtime, the session model handles speech and tool calls together. The application still owns the calendar function and should separate finding an event from updating it. If the user interrupts the spoken reply, confirm that the pending update is also cancelled or withheld. Stopping audio playback is only one part of cancellation. Realtime session overview.

With Gemini Live API, the application streams the conversation and connects the needed tools. The same calendar logic and changed-intent test still apply. Google documents direct client WebSocket connections with ephemeral tokens and server-mediated connections; choose based on your application's media and security needs. That connection choice does not resolve whether an old calendar instruction remains valid. Live API connection options.

The consumer Gemini Live app is suitable for discussing or rehearsing the request. It is not a substitute for evaluating your own application's calendar integration. The availability of an app conversation does not demonstrate custom tool behavior.

Compare completion before conversational polish

Keep the transcript and the calendar's final state together. For this example, the checks are: correct Maya, correct event, correct time zone, no update after cancellation and no duplicate update after a retry. Then compare how long the user waits and whether the voice handles the interruption naturally. A smooth “done” response with the wrong final state fails.

Start with GPT-Live when a working backend agent already owns the calendar workflow and you want conversation to continue around it. Keep Realtime when one session's speech-and-tool design fits your app and passes this scenario. Evaluate Gemini Live API when its streaming voice and vision capabilities fit the product and your implementation can pass the same task checks. Switch only when a specific failed requirement or simpler integration justifies the migration.

Cost and permission checks

Compare complete application cost, not just a token or minute headline. Include the reasoning backend, tools, hosting and any telephone provider. Check current rates directly; this guide does not declare a universal cheapest option.

Keep credentials on the trusted server or use the provider's supported short-lived client credential flow. Obtain the appropriate permission for recordings and connected actions. Give users a clear way to stop a conversation and understand whether pending work was cancelled.

Practical recommendation

Use an app for an immediate personal voice workflow. For a custom product, choose the architecture that fits the task and test it with real acceptance criteria. Keep existing infrastructure when it works; migrate when the observed benefit justifies the change.

See the GPT-Live release note and AI evaluation guide for the next steps.