Side by side

ARES vs Inspect AI

Both stand on llm evaluation tools. Which one you can start free with, which one lets you read the code, and what each costs once you pay.

ARES

Free plan APILinuxSelf-hosted

ARES offers a defined evaluation method for RAG systems, with support for custom models and local execution. Its data and compute requirements are important to account for before setting up an evaluation.

Visit ARES

Inspect AI

Free plan APIExtension

Choose Inspect AI if you need a free, self-hosted framework to evaluate language models across varied task types, with broad provider and agent support. Look elsewhere if you need evaluation runs without access to a model or a hosted deployment.

Visit Inspect AI

The facts

	ARES	Inspect AI
Free plan	Yes	Yes
Open source	Not published	Not published
Runs on	API, Linux, Self-hosted	API, Extension
Lowest paid plan	Not published	Free or on request
Plans published	None	1
Maker	Not published	Not published
Website	github.com	inspect.aisi.org.uk
On llm evaluation tools	#11 of 29	#15 of 29

ARES: what it does well

Evaluates three named aspects of RAG responses.
Supports custom, model-agnostic systems.
Can run locally with vLLM for offline operation.
Open-source under the Apache-2.0 license.
Installation is documented through pip.

What to know first

Requires an in-domain prompts dataset and unlabeled evaluation set.
Local execution needs a GPU.
Local execution needs over about 100 GB of disk space.
At least 50 validation examples are recommended.

Inspect AI: what it does well

Free, open-source framework for model evaluations
More than 200 pre-built evaluations
Supports more than 20 model providers
Includes a VS Code extension and web-based result viewer
Supports MCP tools and multiple agent integrations

What to know first

Evaluation development and runs require access to a model
Self-hosted deployment requires teams to manage their own environment

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