Technology
Open-Source LLM
The short answer
An open-source LLM is a language model whose weights are freely available and can be operated on your own hardware or cloud of choice — unlike proprietary models, which are only usable via the provider's API. Well-known families come from Meta (Llama), Mistral, and others.
Open versus proprietary — weighing the trade-offs
Leading proprietary models (GPT, Claude, Gemini) typically deliver the highest quality across the board, but run exclusively with their providers. Open-source models now deliver genuinely production-ready quality for many clearly defined tasks — classification, extraction, summarisation — and can run entirely on your own infrastructure.
The choice is rarely ideological; it's practical. How sensitive is your data? What's your volume (own hardware can make sense at scale)? How complex is the task? Often the answer is a mix — open source for standard steps, a top-tier model for the hard cases.
What self-hosting requires
Self-hosting means: suitable hardware (GPU servers), operational responsibility (updates, monitoring, scaling) and realistic expectations about model size — the largest open models demand considerable resources, while smaller ones run on single workstations. For many organisations, hosted open source with a EU cloud provider is the practical middle ground.
Licence isn't one-size-fits-all
'Open source' works differently with LLMs: some models are truly free under genuine open-source licences, others come under community licences with restrictions (usage limits or exclusions for certain purposes), and some publish weights only without training data ('open weights'). Before deploying to production, a quick licence check belongs in your project — especially for commercial use.
Good news for European organisations: providers like Mistral offer powerful open models from the EU, and the gap between open and proprietary models has narrowed significantly for many task types. Choice is growing — and with it, your negotiating position with the big providers.
Responsibility comes with it: maintenance and security in self-hosted setups
Running an open model yourself means more than a one-time setup. Unlike API use, where the provider handles operations, updates and security, self-hosted open source puts full responsibility in-house: server maintenance, security updates for the runtime, monitoring load and availability, rolling out new model versions as better ones appear. These ongoing tasks are the real price of maximum control — and they're permanent, not just at launch.
Then there's the security dimension: a self-hosted model with its knowledge base is an attractive target and needs protecting accordingly — access controls, encrypted storage, isolated environments, scrutiny of model sources. For organisations without their own IT operations team, this is often the deciding argument for the middle path: hosted open source with a EU provider who handles operations while you keep data location under control. You get the data-protection advantage of open models without shouldering the full operational load yourself. The honest calculation includes these running costs — not just the API savings.
Practical example
A company with strict data-protection requirements runs an open model on its own GPU server for preprocessing sensitive documents. Only anonymised, non-critical tasks go to an external top-tier model — data never leaves the house uncontrolled.
Frequently asked questions about Open-Source LLM
Are open-source models worse than GPT or Claude?
On the most demanding tasks, proprietary leaders usually win. For bounded standard tasks, the difference is often practically irrelevant — cost, data protection and control matter more.
Is open source automatically more data-friendly?
Only with self-hosting or EU hosting: then data provably stays in your controlled environment. Running an open model via US cloud negates that advantage.
What does running your own model cost?
Hardware (one-off or rented), power and operational overhead — offset against eliminated API costs. At what volume it makes financial sense belongs in your project budget.
What do you have to handle continuously in self-hosting?
Server maintenance, security updates, monitoring load and availability, rolling out new model versions — plus access controls for the model and knowledge base. Without your own IT operations team, hosted open source with a EU provider often works better.
How relevant is this for your business?
In the free intro call we look at your specific process.
This glossary entry was created using AI and machine-translated from German. Editorial responsibility for the German original: Niclas Hoffmann. AI transparency