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AI Prompt Playground

Test Chrome's built-in, on-device Prompt API (Gemini Nano). Tune the parameters, stream the response, and try schema-constrained JSON output — all privately in your browser.
Your browser doesn't support the built-in Prompt API yet.
This playground uses Chrome's on-device Prompt API (LanguageModel). Use the latest desktop Chrome and enable chrome://flags/#prompt-api-for-gemini-nano, then restart. The model downloads once and runs fully offline — nothing you type leaves your device.
Sets the model's role for the whole session (sent as initialPrompts).
Advanced parameters
Higher = more random and creative. Lower = more focused and deterministic.
Number of candidate tokens considered at each step.
Working…
The model's response will appear here.
Runs on-device — nothing you type leaves your browser
About this tool: It's a thin wrapper over the Web Platform LanguageModel API. Temperature and Top-K map to the model's sampling parameters, the system prompt becomes the session's initialPrompts, and the JSON schema is passed as responseConstraint to force structured output.

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