Home/Compare/FastChat vs evals

Comparison

FastChat vs evals

Verdict

Pick FastChat if fastChat is an open-source platform for training, serving, and evaluating large language models, including Vicuna, and supports Chatbot Arena, a platform for LLM evaluations with human feedback; pick evals if evals is an evaluation framework from OpenAI for assessing large language models and systems built with them. It includes an open-source registry of benchmarks and tools to.

Markdown twin · FastChat alternatives · evals alternatives

GraphCanon updated Sep 20, 2026

6views this month

FastChat logo

FastChat

lm-sys/FastChat

★ 40kpushed May 1, 2026
vs
evals logo

evals

openai/evals

★ 19kpushed Apr 14, 2026

Trust & integrity

SignalFastChatevals
Maintenance
Slowing (140d since push)
As of Sep 18, 2026 · github_public_v1
Slowing (145d since push)
As of Sep 7, 2026 · github_public_v1
Provenance
Not a fork · Organization account
As of Sep 18, 2026 · github_public_v1
Not a fork · Organization account
As of Sep 7, 2026 · github_public_v1
OSV dependency advisories
No lockfile (source not queried)
As of Sep 18, 2026 · osv@v1
No lockfile (source not queried)
As of Jul 11, 2026 · osv@v1
deps.dev advisories
Not queried
deps.dev@v1
Not queried
deps.dev@v1
OpenSSF Scorecard
Not queried
openssf-scorecard@v1
Not queried
openssf-scorecard@v1

Tagline

FastChat
An open platform for training, serving, and evaluating large language models
evals
Framework for evaluating LLMs and LLM systems with an open-source registry of benchmarks.

Stars

FastChat
40k
evals
19k

Forks

FastChat
4.8k
evals
3.1k

Open issues

FastChat
1.0k
evals
333

Language

FastChat
Python
evals
Python

Adopt for

FastChat
FastChat is an open-source platform for training, serving, and evaluating large language models, including Vicuna, and supports Chatbot Arena, a platform for LLM evaluations with human feedback.
evals
Evals is an evaluation framework from OpenAI for assessing large language models and systems built with them. It includes an open-source registry of benchmarks and tools to create custom evaluations.

Persona

FastChat
-
evals
-

Runtime

FastChat
-
evals
-

License

FastChat
Apache-2.0
evals
Other

Last pushed

FastChat
May 1, 2026
evals
Apr 14, 2026

Categories

FastChat
Evaluation & Observability, Inference & Serving, LLM Frameworks, Model Training
evals
Evaluation & Observability

Trust and health

Days since push

FastChat
140d
evals
145d

Open issues (now)

FastChat
1.0k
evals
333

Stars delta

FastChat
+19 (30d)
evals
+271 (30d)

Open issues delta

FastChat
+5 (30d)
evals
+120 (30d)

Full report

FastChat
Trust report

Shared compatibility

  • Python · FastChat: Python runtime · evals: Python runtime

Choose FastChat if…

  • License: FastChat is Apache-2.0, evals is Other.
  • Tags unique to FastChat: chatbot arena, llm-evaluation, multi-model serving, openai-compatible apis.
  • Also covers Inference & Serving, LLM Frameworks, Model Training.
  • When you need a platform that supports both training and evaluation of large language models, such as Vicuna, and you want to leverage human feedback for model evaluation.

When NOT to use FastChat

  • If you are looking for a platform that focuses solely on model training without serving or evaluation capabilities, FastChat offers a comprehensive suite that might be more than you need.
  • If your project does not require human feedback for model evaluation, FastChat's integration with Chatbot Arena might be an unnecessary feature.
  • If you are working with proprietary or closed-source models, FastChat's open-source nature and reliance on open-source models like Vicuna might not align with your project requirements.

Choose evals if…

  • License: evals is Other, FastChat is Apache-2.0.
  • Tags unique to evals: benchmarking, custom eval creation, evaluation-framework, large-language-models.
  • * When you need a comprehensive set of pre-existing evals and the ability to create your own tailored tests using specific use cases, especially within the OpenAI model ecosystem.

When NOT to use evals

  • * When evaluating models or systems that do not benefit from being integrated with the OpenAI API, as some features like direct evals configuration in the OpenAI Dashboard require an OpenAI key.
  • * If you are looking for an evaluation framework that doesn’t involve external dependencies such as Git Large File Storage (LFS) and specific Python version requirements (Python 3.9 minimum), or if a

Explore

Sources

Every stat on this page traces to a dated GitHub sync, license file, enrichment field, or trust scan.

GitHub stars on cards: FastChat 40k · evals 19k (synced Sep 20, 2026).

Common questions

What is the difference between FastChat and evals?
FastChat: An open platform for training, serving, and evaluating large language models. evals: Framework for evaluating LLMs and LLM systems with an open-source registry of benchmarks.. See the comparison table for live GitHub stats and shared categories.
When should I choose FastChat over evals?
Choose FastChat over evals when License: FastChat is Apache-2.0, evals is Other; Tags unique to FastChat: chatbot arena, llm-evaluation, multi-model serving, openai-compatible apis; Also covers Inference & Serving, LLM Frameworks, Model Training; When you need a platform that supports both training and evaluation of large language models, such as Vicuna, and you want to leverage human feedback for model evaluation.
When should I choose evals over FastChat?
Choose evals over FastChat when License: evals is Other, FastChat is Apache-2.0; Tags unique to evals: benchmarking, custom eval creation, evaluation-framework, large-language-models; * When you need a comprehensive set of pre-existing evals and the ability to create your own tailored tests using specific use cases, especially within the OpenAI model ecosystem.
When should I avoid FastChat?
If you are looking for a platform that focuses solely on model training without serving or evaluation capabilities, FastChat offers a comprehensive suite that might be more than you need. If your project does not require human feedback for model evaluation, FastChat's integration with Chatbot Arena might be an unnecessary feature. If you are working with proprietary or closed-source models, FastChat's open-source nature and reliance on open-source models like Vicuna might not align with your project requirements.
When should I avoid evals?
* When evaluating models or systems that do not benefit from being integrated with the OpenAI API, as some features like direct evals configuration in the OpenAI Dashboard require an OpenAI key. * If you are looking for an evaluation framework that doesn’t involve external dependencies such as Git Large File Storage (LFS) and specific Python version requirements (Python 3.9 minimum), or if a
Is FastChat or evals more popular on GitHub?
FastChat has more GitHub stars (39,536 vs 19,398). Stars measure visibility, not whether either tool fits your constraints.
Are FastChat and evals open source?
Yes - both are open-source projects on GitHub (FastChat: Apache-2.0, evals: Other).
Where can I find alternatives to FastChat or evals?
GraphCanon lists graph-backed alternatives at FastChat alternatives and evals alternatives (FastChat markdown twin, evals markdown twin), ranked by typed relationship edges rather than popularity votes.
Is there a machine-readable version of this comparison?
Yes. The markdown twin at this comparison mirrors this page for agents and LLM crawlers, with the same stats table and FAQ answers.
Which is better maintained, FastChat or evals?
FastChat: Slowing. evals: Slowing. Compare maintenance labels, days since push, and release cadence in the trust section below - stars alone do not measure maintenance.
Where are the full trust reports for FastChat and evals?
GraphCanon publishes per-repo trust reports with dated maintenance, provenance, and scan summaries: FastChat trust report; evals trust report.

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