Custom Gemma AI system prompt to create own chatbot experience
I want to create custom chatbot experience. I want to be based on Google’s Gemma AI Large Language Models. I find Gemma3, especially 27b version very capable while problem solving. It has been trained on such data that I find it interesting. I will use Open WebUI to create custom “model hat” and provide chatbot experience
TLDR
In order to create your own chatbot, only 3 steps are required:
- Pull origin model
- Define custom hat model atop on origin model
- Specify System Prompt and other features
To create own chatbot experience I can use System Prompt feature which is core part of model itself. Running on Ollama, Gemma3:27b is actually a 4-bit quantized version of full 16-bit non-quantized model weights. Furthermore it means that GPUs without FP16 support will force model to be run in 32-bit mode increasing memory consumption. It is closed-loop, because older GPUs without FP16 will have less memory to lack of support will amplify the problem.
Effective number of context tokens in Gemma2 or Gemma3 varies between 8k and 128k. This value holds space for system prompt, user prompt ans response. In case context window is exceeded, engine should crop it.
How to create own model hat to serve as chatbot
To create own “model hat”, which is actually system prompt you can use Web UI. Go to workspace – models.
You can define then System Prompt and other features like filters and actions:
Your are good to go.
Conversation
So I created new chat, selected my newly created model and started conversation.
I said that I cannon open some website. It answered with some predefined suggestions, like opening it in new browser tab, in private mode or in different browser. i then continued with confirmation that I have tried indeed:
I can go outside of predefined scenario and ask additional questions. This time we utilize unbiased potential of Gemma:
In the end, if we are left with no other options, we suggest contacting support via email:
Please note that support email which Gemma suggested is not real and it has been fantasized.