Which LLMs are supported?
Currently, LibreThinker only runs OpenAI's GPT-5-mini model. Support for additional models, and LLM vendors, will be added in future.
LibreThinker is an extension that enables you to edit text using an LLM integrated in your LibreOffice Writer sidebar.
>> Try it out
How to install
Download the extension from the LibreOffice extensions directory. Either open the file; or, open LibreOffice Writer, go to Tools > Extension Manager > Add, and select the downloaded .oxt file.
Restart LibreOffice Writer, then open the sidebar. You should now see the LibreThinker (lightbulb) icon there. Click on it, and you are ready to start.
Note on model quality: By default, the extension falls back to a free model, which is of lower quality. For best results, it's recommended to use an OpenAI model (see below).
OpenAI model
Obtain an API key on the OpenAI platform, and set it as the LT_LLM_API_KEY environment variable in your operating system.
Restart LibreOffice Writer. The extension will now use the API key from your environment variable to generate the text.
FAQ
Is it free?
LibreThinker does not charge for usage. However, you will be charged by the LLM vendor for using their API.
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. There are two reasons for this:
- 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 then deploy updates to the backend without requiring users to update the extension.
How are my API keys secured?
Your API key is never stored on disk by the extension or the backend server. It is only held temporarily in memory, to pass your request to the LLM vendor's API, after which it is discarded.
How is my privacy protected?
Neither the extension, nor the backend server, store any of the text you send for processing.
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.