head to head · open source
llama_index vs Arize Phoenix
llama_index has 52,779 GitHub stars, 8,500 forks, 770 open issues and last shipped 8 days ago. Arize Phoenix has 12,106 stars, 1,258 forks, 970 open issues and last shipped yesterday. llama_index leads on adoption by 336% (52,779 vs 12,106 stars). llama_index is written in Python under MIT; Arize Phoenix is written in Python under a custom or non-standard licence. llama_index has attracted 16% 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. The two share 2 topic tags (agents, llamaindex), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| llama_index | Arize Phoenix | |
|---|---|---|
| GitHub stars | ★ 53K | ★ 12K |
| License | MIT | Custom / other |
| Written in | Python | Python |
| Last push | 2026-10-26 | 2026-11-02 |
| Forks | ⑂ 8.5K | ⑂ 1.3K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick llama_index if
- You weight community size — 53K stars and counting
- You want the MIT license terms
- Your stack matches Python
- You value the larger contributor base for long-term maintenance
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
About llama_index
🗂️ LlamaIndex (OSS Framework) 🦙 [!NOTE] The current focus of LlamaIndex is to build the best AI powered engine for document parsing and extraction. LlamaParse is our enterprise platform for agentic OCR, parsing, extraction, indexing and more. LiteParse represents our efforts to build the best free, fast, cheap text parser in the market. ParseBench and ExtractBench represent our commitment towards open benchmarking for parsing and extraction. The company itself has undergone an evolution since when this OSS framework first launched 3 years ago in 2023. Since the early days, the framework has consisted of a…
read the full llama_index 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_index or Arize Phoenix more popular?
llama_index has 52,779 GitHub stars and Arize Phoenix has 12,106. llama_index has the larger community by that measure.
Are llama_index and Arize Phoenix free?
Both are open source. llama_index 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_index and Arize Phoenix?
llama_index is written in Python 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_index or Arize Phoenix?
Choose llama_index if you want the larger community (52,779 stars) or its MIT licence terms. Choose Arize Phoenix if its feature set, stack or Custom / other licence fits better. Both are self-hostable.