Every "which inference server should we run" thread turns into a benchmark fight within about four replies. Someone posts tokens/sec for a model nobody else is running, at a batch size nobody states, on a GPU nobody else has. It is the wrong argument. The number that actually decides this is concurrency. Not team size. Concurrency. "We have 50 engineers" is not 50 concurrent requests. Fifty engineers, working the same timezone, using an internal assistant a handful of times an hour, with each request taking a few seconds, gives you a peak concurrency in the low single digits. I would bet on 2 to 5 for most internal tooling. That is a wildly different engineering problem from 50, and it points at a different server. Go and measure it before you read another benchmark. Peak concurrent in-flight requests, over a normal week. Every gateway, proxy or server you already run can tell you. If you skip this step, everything downstream is guesswork. Now the part people get wrong about the three tools: they are not three competitors at the same layer. llama.cpp is an inference engine. C++, GGUF weights, and by far the widest hardware reach of the three: CPU, Apple Silicon via Metal, CUDA, ROCm, Vulkan. Minimal dependencies. It ships a server binary. If you are on an air-gapped box, odd hardware, no GPU, or a machine where installing a CUDA stack is a six-week change request, this is the one that will actually run. Ollama is llama.cpp with a model manager and a good UX bolted on. Single binary, pull a model, it works in minutes. That ease is why most teams start here, and starting here is usually correct. vLLM is a different category. It is a serving system built for throughput, and its whole design centre - continuous batching, paged KV cache - is about making aggregate throughput scale as concurrency rises. That is the thing it does that the other two do not do as well. Which means the choice is nearly decided by your concurrency number. Low single-digit concurrency, and vLLM's central advantage is mostly dormant while you pay its operational cost: CUDA and driver version alignment, a heavier dependency stack, more to go wrong at 2am. High and sustained concurrency, especially batch work, and that same advantage is the entire reason you would run anything else.