Takes about 5 minutes

Connect LibreChat to PromptUnit

LibreChat connects to PromptUnit as a custom endpoint: one variable in your .env file and a few lines in librechat.yaml.

Get your PromptUnit key

Sign up free at PromptUnit (no credit card) and connect the AI provider key you already use, for example your OpenAI or OpenRouter key. Your requests keep running on that key.

Then open API Keys in your dashboard and copy your PromptUnit key. Connecting more than one app? Under Routing, + New routing gives each app its own key and settings.

Add your key to .env

In the .env file of your LibreChat install, add:

PROMPTUNIT_API_KEY=your PromptUnit key from Step 1

Add the endpoint to librechat.yaml

Under endpoints: → custom:, add:

endpoints:
  custom:
    - name: "PromptUnit"
      apiKey: "${PROMPTUNIT_API_KEY}"
      baseURL: "https://www.promptunit.ai/api/proxy/openai"
      models:
        default: ["gpt-6.1-sol"]
        fetch: true
      titleConvo: true
      titleModel: "current_model"
      modelDisplayLabel: "PromptUnit"

The baseURL above is for an OpenAI key. With a different provider's key connected in PromptUnit, use its address instead:

OpenAI: https://www.promptunit.ai/api/proxy/openai
OpenRouter (models from many providers): https://www.promptunit.ai/api/proxy/openrouter
Google Gemini: https://www.promptunit.ai/api/proxy/google
Groq: https://www.promptunit.ai/api/proxy/groq
DeepSeek: https://www.promptunit.ai/api/proxy/deepseek

With fetch: true, LibreChat loads the models your own provider account can use; the default list is the fallback.

Restart LibreChat and pick PromptUnit

Restart LibreChat so it reads the new settings (with Docker: docker compose restart). Then choose PromptUnit in the endpoint menu and pick a model.

Watch the costs

Each message shows up on your PromptUnit dashboard with what it cost. PromptUnit checks every request and uses a cheaper model only when it would answer just as well; otherwise it uses the model you chose. Your first $5 of savings is free, no card needed.

If something doesn't look right

If PromptUnit doesn't appear in the menu, check the indentation in librechat.yaml (spaces, not tabs) and that LibreChat was restarted. If the model list is empty, check that the same provider's key is connected in PromptUnit.

Quick reference

The address you'll paste in, if you need it again:

https://www.promptunit.ai/api/proxy/openai