What is an open-source model?
An open-source model ships under a license that lets you inspect, run, and sometimes modify it. Open weights means you can download the trained parameters even if every training detail is not public. Someone still has to host it, update it, and watch the bill.
Also called: open weights
In plain English
You are not free of vendors just because the model file is downloadable. You trade a chat subscription for a server, a person who can keep it running, and your own data handling. A small language model is about size. Open source is about the license. A model can be small and closed, or large and open. Open weights are a file you can run, not a free employee. Someone still pays for the machine, the updates, and the person who watches it. Read the license far enough to know if you can use it in a business. If you do not want to host anything, a hosted model is the honest choice. Do not pick an open model only because a chart said it was smart.
How an owner would use it
Choose open source if you have a real reason: a host you control, a license your counsel accepted, or a feature the hosted apps will not turn off. If you do not have anyone to operate it, a normal hosted app is the smaller job.
Common mistakes
Downloading a model because a post said it is free ignores electricity, time, and the license text. Some 'open' licenses restrict commercial use. Read the license. Do not assume open source means the outputs are cleared for your ads. Do not skip data handling because you are not paying a famous vendor.
A worked example
A community workshop
They wanted the file, then saw the upkeep
This is an illustration, not a customer result. A member offers to run an open-weight model on a workshop computer for class handouts. The board asks who patches it and where student names go. Nobody owns that job. They keep using a hosted tool with a ban on student contact lists.
Related terms
Prompts and guides
Questions owners ask
What is an open-source model?
It is a model you can run under a published license, instead of only calling it through a vendor's chat product.
How do I decide if an open model is worth it?
List who will host it, who will update it, and which data will touch it. If those names are blank, stay on a hosted app you can read the terms for.
What are open weights?
Open weights means the trained parameters are published so you can run the model. It does not always mean the full training code and data are public. Check the project, not the slogan.
Product guides are on AI apps for business.