Simulate the Google Gemini API

Summary

This sample contains mock responses that allow you to simulate the Google Gemini API using Dev Proxy. Simulating the Gemini API is useful when you’re working on parts of your app that don’t require a real response from Gemini and don’t want to incur unnecessary API costs.

Compatibility

Contributors

• Waldek Mastykarz

Version history

Minimal path to awesome

• Get the sample:

  • Download just this sample:

    npx gitload-cli https://github.com/pnp/proxy-samples/tree/main/samples/simulate-google-gemini

    or

  • Download as a .ZIP file and unzip it, or

  • Clone this repository

• Start Dev Proxy by running devproxy
• Test with: curl -ikx http://127.0.0.1:8000 "https://generativelanguage.googleapis.com/v1beta/models/gemini-2.0-flash:generateContent?key=test-api-key" -d '{"contents":[{"parts":[{"text":"Hello"}]}]}' -H "content-type: application/json"

Features

Using this sample you can:

• Simulate responses from the Google Gemini generateContent endpoint without needing an API key
• Simulate responses from the countTokens endpoint
• Simulate responses from the embedContent endpoint
• Simulate listing and retrieving model information
• Avoid incurring API costs during development and testing
• Develop and test your app’s UI and integration logic with realistic Gemini response shapes

The mock responses follow the official Google Gemini API response format, including usageMetadata with token counts and safetyRatings.

To customize the mock responses, edit the .devproxy/mocks.json file. You can add additional mock responses for different scenarios, such as function calling, thinking, or multi-turn conversations.

Help

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Disclaimer

THIS CODE IS PROVIDED AS IS WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING ANY IMPLIED WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR NON-INFRINGEMENT.