head to head · open source

llama.cpp vs Arize Phoenix

llama.cpp has 133,181 GitHub stars, 25,063 forks, 2,464 open issues and last shipped yesterday. Arize Phoenix has 12,106 stars, 1,258 forks, 970 open issues and last shipped yesterday. llama.cpp leads on adoption by 1,000% (133,181 vs 12,106 stars). llama.cpp is written in C++ under MIT; Arize Phoenix is written in Python under a custom or non-standard licence. llama.cpp has attracted 19% as many forks as stars, Arize Phoenix 10%. Arize Phoenix was the more recently maintained of the two, and both are self-hostable with no licence fee.

Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.

llama.cpp ★ 133K Arize Phoenix ★ 12K category AI & Machine Learning

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Side by side

	llama.cpp	Arize Phoenix
GitHub stars	★ 133K	★ 12K
License	MIT	Custom / other
Written in	C++	Python
Last push	2026-11-02	2026-11-02
Forks	⑂ 25K	⑂ 1.3K
Self-hosting	Yes	Yes
Data ownership	Your server	Your server

pick llama.cpp if

You weight community size — 133K stars and counting
You want the MIT license terms
Your stack matches C++
You value the larger contributor base for long-term maintenance

full llama.cpp profile →

pick Arize Phoenix if

You want the Arize Phoenix feature set and don't need the biggest community
You prefer the Custom / other license terms
Your stack matches Python
You evaluated both and Arize Phoenix fits your workflow better

full Arize Phoenix profile →

About llama.cpp

llama.cpp LLM inference in C/C++ ggml / ops / maintainer PRs%20sort%3Aupdated desc) / dev stats / lib llama API / llama server REST API Quick start A few options to get llama.cpp installed on your machine: Visit and follow the instructions Run with Docker see our Docker documentation Download pre built binaries from the releases page Build from source by cloning this repository check out our build guide Once installed: VLM session with llama cli Built in web UI against llama serve Description The main goal of llama.cpp is to enable LLM (and VLM) inference with minimal setup and state of the art performance on a…

read the full llama.cpp overview →

About Arize Phoenix

English · 简体中文 Arize Phoenix is Arize's open source AI observability platform designed for experimentation, evaluation, and troubleshooting. For managed production workflows, Arize also offers Arize AX. Phoenix provides: Tracing Trace your LLM application's runtime using OpenTelemetry based instrumentation. Evaluation Leverage LLMs to benchmark your application's performance using response and retrieval evals. Datasets Create versioned datasets of examples for experimentation, evaluation, and fine tuning. Experiments Track and evaluate changes to prompts, LLMs, and retrieval. Playground Optimize prompts, compare…

read the full Arize Phoenix overview →

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Frequently asked questions

Is llama.cpp or Arize Phoenix more popular?

llama.cpp has 133,181 GitHub stars and Arize Phoenix has 12,106. llama.cpp has the larger community by that measure.

Are llama.cpp and Arize Phoenix free?

Both are open source. llama.cpp is licensed under MIT, and Arize Phoenix has no licence declared in this registry. Both are free to self-host.

What is the difference between llama.cpp and Arize Phoenix?

llama.cpp is written in C++ and Arize Phoenix in Python. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.

Which should I choose, llama.cpp or Arize Phoenix?

Choose llama.cpp if you want the larger community (133,181 stars) or its MIT licence terms. Choose Arize Phoenix if its feature set, stack or Custom / other licence fits better. Both are self-hostable.