📖 The AI Tool Bible

Evaluation

Observability, prompt testing, and quality scoring.

48 tools

Why it matters

Evaluation is the discipline most underinvested in by AI product teams. Choosing an eval tool early is much cheaper than retrofitting one when an LLM regression hits production.

What's in here

Spans full eval + observability platforms (Braintrust, LangSmith), prompt management (Humanloop, PromptLayer), ML-broad tracking with LLM features (Weights & Biases), and proxy-based observability (Helicone).

How to pick

Pick Braintrust or LangSmith for full eval + observability. Pick Humanloop if PMs need to edit prompts. Pick Helicone for a one-line install on existing OpenAI/Claude code. Pick Patronus for automated hallucination/safety evals at scale.

LLMEval

Evaluation · Multi-model
7.2

Open academic benchmark suite for stress-testing LLMs on contamination-resistant, domain-specific tasks.

Free· Free; open-source academic benchmarksllm-benchmarkingacademic-evaluation

Promptfoo

Evaluation · Multi-model
7.2

Open-source eval and red-teaming framework for LLM apps, prompts, and RAG pipelines.

Freemium· Open-source free; Enterprise SaaS contact salesllm-evalsred-teaming

Weco AI

Evaluation · Multi-model (LLM + AIDE tree search)
7.2

Autoresearch engine that iteratively rewrites code to optimize against a numeric evaluation metric.

Freemium· Open-source CLI; hosted/commercial pricing not publishedcode-optimizationgpu-kernel-tuning

AlpacaEval

Evaluation · GPT-4 Preview (Nov 2024) as annotator
7.1

Automatic LLM evaluator and leaderboard that benchmarks instruction-following with length-controlled win rates.

Free· Free and open-source; pay only for the underlying OpenAI annotator API callsllm-benchmarkinginstruction-following eval

Arthur

Evaluation · Multi-model
7.1

Open-source toolkit for testing, tracing, and monitoring production AI agents.

Freemium· Open-source (MIT) + free SaaS tier; paid/enterprise plans on requestagent-evaluationprompt-management

Fiddler AI

Evaluation · Fiddler Centor (proprietary evaluators)
7.1

Enterprise AI observability and guardrails platform for monitoring agents, LLMs, and ML models in production.

Enterprise· Tiered plans; contact salesllm-observabilityagent-monitoring

Maxim AI

Evaluation · Multi-model
7.1

End-to-end evaluation, simulation, and observability platform for shipping production-grade AI agents.

Freemium· Free tier; 14-day trial on paid plans; custom enterprise pricingagent-evaluationllm-observability

Prompt Foundry

Evaluation · OpenAI + Anthropic (multi-model)
7.1

Prompt management and side-by-side LLM evaluation for OpenAI and Anthropic models.

Freemium· Free tier (10 prompts, 500 evals/mo); Pro $15/user/mo; Enterprise customprompt-managementmodel-comparison

Respan (formerly Keywords AI)

Evaluation · Multi-model (500+ via gateway)
7.1

LLM engineering platform combining a multi-model gateway with tracing, evals, and prompt management.

Freemium· Free tier; paid plans (pricing not public); enterprise on requestllm-observabilityprompt-management

SEAL Leaderboard

Evaluation · Multi-model (GPT, Claude, Gemini, Llama, etc.)
7.1

Private, expert-graded leaderboards from Scale AI that rank frontier LLMs on domains contaminated public benchmarks can no longer measure.

Free· Free to view; paid custom evals via Scale enterprise salesmodel-selectionbenchmark-tracking

VisualWebArena

Evaluation · Model-agnostic (GPT-4V, Gemini, Claude, open VLMs)
7.1

Open benchmark for evaluating multimodal web agents on realistic visual browsing tasks.

Free· Free and open source (MIT-style research release)multimodal-agent-evalweb-browsing-benchmark

LangFast

Evaluation · Multi-model
7.0

No-signup LLM playground for testing, comparing, and versioning prompts against your own API keys.

Paid· One-time lifetime ~$60-$120; 14-day money-backprompt-testingprompt-versioning

OlympicArena

Evaluation · GPT-4o, Claude-3.5-Sonnet, Doubao-Pro-32k, DeepSeek-Coder-V2, Qwen2-72B-Instruct
7.0

Olympiad-level multi-discipline benchmark for stress-testing reasoning in LLMs and multimodal models.

Free· Free, open-source research benchmarkllm-evaluationmultimodal-eval

Phoenix

Evaluation · Multi-model
7.0

Open-source LLM and agent observability platform with tracing, evals, and experimentation built on OpenTelemetry.

Freemium· Open source (ELv2) + free Phoenix Cloud; paid Arize AX for enterprisellm-tracingagent-debugging

Superwise

Evaluation · Multi-model
7.0

Agentic management platform for runtime guardrails, policy enforcement, and observability across LLM agents.

Freemium· Free Starter Edition; paid tiers via salesllm-guardrailsai-governance

llmfit

Evaluation · Multi-model
7.0

Terminal tool that scores hundreds of open LLMs against your actual CPU, RAM, and GPU and tells you which ones will run well.

Free· Free, MIT-licensedlocal-llm-selectionhardware-benchmarking

Agenta

Evaluation · Multi-model
6.9

Open-source LLMOps platform for prompt engineering, evaluation, and observability in one workspace.

Freemium· Open-source self-host free; managed cloud has free tier plus paid plansprompt-engineeringllm-evaluation

CompassRank

Evaluation · Multi-model
6.9

Public leaderboard from the OpenCompass project ranking open and closed LLMs across 100+ benchmarks.

Free· Free leaderboard; OpenCompass toolkit is Apache 2.0 open sourcellm-benchmarkingmodel-selection

InfiBench

Evaluation
6.9

Stack Overflow-derived benchmark for evaluating code LLMs on real-world programming questions.

Free· Free and open source (CC BY-SA 4.0)code-llm-evalmodel-benchmarking

MixEval

Evaluation · GPT-3.5-Turbo-0125, GPT-4o-2024-05-13, Claude 3.5 Sonnet, MixEval, MixEval-Hard
6.9

Dynamic LLM benchmark that mixes web queries with existing datasets to mirror Chatbot Arena rankings at a fraction of the cost.

Free· Free and open sourcellm-benchmarkingmodel-ranking

Arena AI

Evaluation · Multi-model
6.8

Head-to-head LLM battle arena with a public leaderboard for ranking AI models.

Free· Free to use; no public paid tier listedllm-benchmarkingmodel-comparison

Artificial Analysis

Evaluation · Multi-model
6.8

Independent benchmarking platform comparing AI models and inference providers across intelligence, speed, and cost.

Freemium· Free public leaderboards; paid plans for expanded data and reports (contact for pricing)model-benchmarkingprovider-comparison

Cleanlab TLM

Evaluation · Multi-model (wraps any LLM)
6.8

Trustworthiness scoring layer that flags LLM hallucinations in real time.

Freemium· Free tier for evaluation; usage-based API pricing; enterprise/private deployment via saleshallucination-detectionrag-evaluation

Parea AI

Evaluation · Multi-model
6.8

LLM evaluation, observability, and prompt management platform for teams shipping production AI apps.

Freemium· Free (2 seats, 3k logs/mo); Team $150/mo; Enterprise customllm-evaluationprompt-management