Lemma
Lemma is a YC Fall 2025 (F25) company. Based in San Francisco, CA, USA. Team of 2.
About Lemma
Summary
Lemma builds production monitoring and continuous improvement infrastructure for AI agents. It audits every agent trace against the agent's own instructions, surfaces recurring failures, pinpoints the exact steps that cause them, and delivers fixes automatically via API or pull request. Teams replacing manual prompt tuning and reactive debugging with Lemma get agents that correct themselves in production rather than degrading silently.
Business model
API access with a demo-first sales motion, exact pricing not public.
Go-to-market
Engineering teams shipping AI agent products are the buyers; they connect Lemma to their codebase or API, receive Slack alerts on new issues, and resolve failures through a coding-agent integration without leaving their existing workflow.
From the Y Combinator listing
Continuous learning for AI agents
Lemma enables AI agents to continuously improve from user feedback and production outcomes. Instead of relying on manual prompt tuning and reactive debugging, Lemma detects when an agent’s performance drifts, pinpoints the exact step causing failures, generates optimized prompt candidates, and automatically delivers improvements through our API or by opening a pull request in your codebase. Built by ex-AI engineers who felt this pain firsthand, Lemma turns static agents into self-improving systems, helping teams ship reliable AI products faster with compounding performance gains over time. Deploy 1x. Learn forever.
Facts
- B2B / B2B -> Engineering, Product and Design
- San Francisco, CA, USA
- 2
- Active
- Early
Founders (2)
Score every batch against your own thesis
GPAgent's sourcing agent reads every company in a batch, scores each one against your fund's thesis in a private workspace, and lines up the founders worth meeting before Demo Day. You decide who to contact. Your scores, notes, and pipeline never appear on these pages.
How Accelerator intelligence works