AI builder glossary
Local LLM
A language model running on hardware you control, such as a laptop or your own server, with no third-party API involved in generating the output.
A local LLM is a model you run yourself rather than reach through a provider's API. In practice that means an open-weight model, usually quantized, served by a tool such as Ollama, llama.cpp, LM Studio, or vLLM. Ollama and vLLM expose OpenAI-compatible endpoints, so the same client code can talk to a local model or a hosted one by changing a base URL.
Builders reach for local models for a few reasons: data that must not leave a machine or network, workloads large enough that per-token pricing hurts, offline products, and development loops where you want to iterate without spending. It's also a cheap way to prototype a feature before choosing a provider.
The mistake is assuming local means free and equivalent. You pay in hardware, memory limits, setup, and operations, and a model small enough for a laptop will be weaker than a frontier model on open-ended or reasoning-heavy work. Local models shine on narrow, well-specified tasks: classification, extraction into a schema, short rewrites, embeddings. Treat the choice like any model decision: run your eval set against the local candidate and compare it with the hosted baseline before you switch.
A law firm's document-tagging tool can't send client files to any outside service. The team runs a quantized open-weight model under Ollama on an office server, calls it through the OpenAI-compatible endpoint, and checks its tags against a labeled sample every time they change models.
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