Developer tools for testing and evaluating LLM agents, seed stage

1. AgentOps — Open-source SDK and platform for tracing, debugging, and evaluating LLM-agent behavior across tool calls and multi-step runs; fits as a YC-backed early-stage company focused specifically on agent observability and testing.
2. Langfuse — Open-source LLM engineering platform for traces, prompt management, datasets, and evaluations; fits as a YC-backed company that raised an early seed round and remains closely aligned with developer infrastructure for agent applications.
3. Parea AI — Provides prompt/version management, test suites, monitoring, and regression evaluation for LLM applications and agents; fits as a seed-stage startup with early venture backing and a developer-centric product.
4. Maxim AI — Offers an end-to-end platform for simulating, testing, evaluating, and monitoring AI agents before and after deployment; fits as a genuinely early company with a publicly announced seed round and a particularly direct agent-testing focus.
5. LangWatch — Provides tracing, analytics, prompt experimentation, and LLM evaluation workflows for production AI systems; fits as a young, accelerator-backed company building infrastructure for developers shipping agentic applications.
6. Confident AI — Creator of DeepEval, an open-source framework for testing LLM systems using metrics such as hallucination, relevance, faithfulness, and task completion; fits as a seed-stage company whose open-source adoption is a strong developer signal.
7. Giskard — Open-source testing and quality platform covering vulnerabilities, hallucinations, bias, and reliability in ML and LLM applications; fits as an early venture-backed company with a clear testing wedge, including agent and RAG systems.
8. HoneyHive — Developer platform for tracing, experimenting with, and evaluating LLM applications, including multi-step workflows and agents; fits as a seed-funded startup with early enterprise traction in LLM quality infrastructure.
9. Traceloop — Builds OpenLLMetry and related tooling for tracing, monitoring, and evaluating LLM and agent applications using OpenTelemetry; fits as a seed-stage company with an open-source distribution strategy and strong relevance to agent debugging.
10. Literal AI — Offers observability, prompt management, datasets, and evaluation tooling for conversational AI and LLM applications; fits as an early, pre-seed/seed-backed company focused on the developer workflow rather than building models or end-user agents.

White-space gaps noticed:

• Agent-specific evaluation grounded in business outcomes: Most tools measure generic criteria such as latency, cost, faithfulness, or answer quality; there is room for systems that automatically evaluate whether an agent actually completed a real-world workflow correctly across long horizons.
• Reliable testing for non-deterministic, tool-using agents: The market lacks mature “CI/CD for agents” that can replay environments, mock APIs and permissions, test recovery from failures, detect unsafe side effects, and provide stable regression gates for agents operating in production systems.