Build. Experiment. Scale. Now With Open-Source AI Evaluation.
AI is evolving faster than ever—but making it work at scale is still a massive challenge. The need for a robust AI evaluation engine has never been more critical as organizations deploy increasingly complex models and systems.
If you're building AI-powered applications, you already know the pain points:
- Models underperform or degrade in production
- LLMs go off the rails with unpredictable outputs
- There's no easy way to evaluate AI performance in real time
- Tuning and debugging models slows down iteration
That's why we're launching the Arthur Engine—an open-source, real-time AI evaluation engine for both Generative AI and traditional ML models. No black-box monitoring. No third-party dependencies. No data privacy risks. All for free.
🔗 Get it on GitHub. Start evaluating your models today.
Why Real-Time AI Evaluation Matters in 2025
You're not just running models—you're shipping products, large-scale systems, and AI-powered experiences. But without real-time AI evaluation and guardrails, things can go sideways fast.
- LLMs leak sensitive data—According to Harmonic Security, 8.5% of employee prompts to LLMs contain customer or employee data.
- AI models degrade over time—Without real-time feedback, model drift and performance failures go unnoticed.
- Debugging AI is a nightmare—You need faster iteration and visibility into why models break in production.
The Arthur Engine is built to fix this. It helps you catch failures, enforce safety guardrails, mitigate risks and optimize models in real time—right inside your own environment.
"AI is moving fast, and we need to make sure it moves in the right direction. Open-sourcing the Arthur Engine puts powerful AI evaluation tools into the hands of developers, researchers, and builders worldwide." — Ashley Nader, Lead AI PM at Arthur
The Open-Source AI Monitoring Revolution Begins Now
Unlike existing solutions that require you to send data to a third-party platform, the Arthur Engine runs locally, inside your own stack. This open-source AI monitoring tool fundamentally changes how teams can ensure model quality at scale.
Key Capabilities of the Arthur Engine
- Real-Time AI Evaluation – Instantly analyze model outputs and detect failures before they impact production, giving you immediate visibility into performance issues.
- Active Guardrails & Continuous Monitoring – Apply guardrails that intervene in real-time to prevent bad outputs, while passively tracking performance over time.
- Customizable Metrics and Safeguards – Leverage the Arthur Engine with any of your existing custom measurements along with Arthur’s default evaluations.
- Privacy-Preserving & Secure – Evaluations happen inside your environment—no external access, no data leaks, no compliance headaches.
- Instant Access for Builders & Hackers – Clone the repo, drop it into your pipeline, and start evaluating models today.
- LLM & Model Agnostic – Whether you're deploying GPT, Claude, Gemini, open weights models, or traditional ML models, the Arthur Engine helps you monitor, validate, and fine-tune performance.
“At Arthur, we believe that all growth powered by AI should be sustainable, transparent, and safe. By open sourcing the Arthur Engine, we are making trust and safety accessible to all AI developers by allowing them to monitor and safeguard their use cases. While being fully customizable, the OSS Arthur Engine leverages community validated, high performance open-sourced ML safety systems out of the box to protect your interactions with Generative models and AI agents.” — Cherie Xu, Technical Lead, Machine Learning at Arthur
Transforming AI Workflows with Real-Time AI Evaluation
The Arthur Engine represents a significant leap forward in how teams can monitor and improve AI systems. By providing real-time AI evaluation capabilities as an open-source solution, we're democratizing access to tools previously available only to organizations with substantial resources.
When monitoring AI systems in production, timing is everything. Real-time evaluation means catching problematic outputs before they reach users, preventing negative downstream impact to your business and reputation.
Open-Source AI Monitoring That Preserves Your Data Sovereignty
One of the biggest challenges with existing AI monitoring solutions is the requirement to share sensitive data with third-party vendors. The Arthur Engine's open-source approach keeps your data where it belongs—in your environment.
Our open-source AI monitoring framework provides:
- Complete transparency into evaluation methodologies
- Customizable metrics and thresholds
- Community-driven improvement and extension
- Freedom from vendor lock-in
Built for AI Builders—Now Even Stronger
This OSS launch comes alongside a major revamp of the Arthur Platform—our enterprise-grade AI performance monitoring suite.
What's New in Our AI Evaluation Engine?
- Enterprise AI Control & Monitoring – A unified platform for tracking AI performance across teams and use cases.
- Actionable Insights & Analytics – Get real-time alerts, explainability, and compliance tools to debug and optimize models.
- Data Stays in Your Environment – Federated monitoring eliminates third-party risk. Your AI, your infrastructure.
- New Intuitive UI – Deploy and monitor models in minutes with an easy-to-use interface built for speed and scale.
With Arthur's Open-Source Engine + Enterprise AI Platform, you can build, scale, and optimize AI performance—without sacrificing security, speed, transparency, or control.
Why Organizations Need a Dedicated AI Evaluation Engine in 2025
As AI deployments mature and grow in complexity, the risks of underperforming models increase exponentially. Arthur’s dedicated AI evaluation engine provides the infrastructure needed to:
- Continuously validate model outputs against expected parameters
- Detect subtle shifts in performance before they become problematic
- Provide auditability and explainability for regulatory readiness
- Enable faster iteration, cycles with confidence
The real-time nature of Arthur's evaluation capabilities means issues are caught at the source, not after they've impacted users or business outcomes.
Start Building With Arthur Today
This is just the beginning. We're committed to making AI evaluation and observability accessible to everyone—so you can move fast, build smarter, and deploy AI with confidence.
Our open-source AI monitoring solution sets a new standard for transparency and effectiveness in the industry. By bringing real-time AI evaluation to everyone, we're helping ensure AI systems work as intended, respect privacy boundaries, and deliver consistent value.
🔗 Explore the Arthur Engine on GitHub
🛠️ Join the waitlist for the new Arthur Platform
AI is reshaping the world—let's make sure it performs the way it should with the most advanced AI evaluation engine available today.
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