Is LibreThinker free?
LibreThinker does not charge for usage of the free models. If you
bring your own API key, you will be charged by the LLM vendor
according to their pricing.
AI Copilot for LibreOffice Writer
LibreThinker adds an AI writing assistant directly into the LibreOffice Writer sidebar. Rephrase text, summarize documents, proofread, and get unstuck - without leaving your editor.
Use a free LLM (no signup required), or bring your API key and connect to a wide range of vendors including OpenAI, Mistral, Groq, and many more!
>> Get the extension
How to install
Download the extension from the LibreOffice extensions directory. Open LibreOffice Writer, go to Tools > Extension Manager > Add, and select the file.
Restart LibreOffice Writer, then open the sidebar (View > Sidebar). You should now see the LibreThinker icon there (a lightbulb). Click on it, and you are ready to start with the free model!
Bring your API key
Go to LiteLLM's model directory, and find the model that you wish to connect to. Copy its value from the Model column; for example, gpt-5.2 or mistral/mistral-medium.
Set the value as the LT_LLM_MODEL environment variable in your operating system. Then set the API key as the LT_LLM_API_KEY environment variable.
Restart LibreOffice Writer. The extension will now use the LLM vendor's API, with your key, to generate the text.
FAQ
Why doesn't LibreThinker directly connect to the LLM vendor's API?
The extension sends requests to a backend server, which then forwards them to the LLM vendor's API. This design has a few advantages:
- It minimizes the dependencies required in the extension, which makes installation easier and reduces the chances that you'll encounter compatibility issues.
- I can identify bugs and performance problems more easily.
- I can fix bugs and add new features to the backend without requiring users to update the extension.
How are my API keys secured?
Your API key is only stored temporarily on the server, to pass your request to the LLM vendor's API, after which it is discarded.
How is my privacy protected?
The text you send for processing, and the response, are only stored
temporarily while your request is being fulfilled. They're both
deleted when the request is completed.
Do you offer a self-hosted version for maximum privacy/security?
Yes, I offer a fully self-hosted version of LibreThinker as a paid service.
With the self-hosted option, all requests stay entirely within your own infrastructure. No traffic passes through my servers, giving you full control over your data, API keys, and deployment environment.
Contact me to find out more.
About
Hi there! My name is Mihail and I'm a software engineer based in the the most boring place in the world. I decided to build this extension because I was often switching between LibreOffice Writer and ChatGPT when editing my CV.
I've been working on this in my evenings and weekends, and I'd be grateful for any support you can provide. Positive reviews, spreading the word, PRs to the GitHub repository, or anything else you can think of!
Want to get in touch? Contact me.