Thirdlayer (YC W25) — Continual learning for enterprise AI
ThirdLayer is the learning and alignment layer for enterprise AI. We continuously ingest and structure messy organizational context, complex operational processes, and siloed, permission-sensitive data, then grade agents against the outcomes each company cares about.
Thirdlayer is a Y Combinator company in the Winter 2025 batch. Its directory entry describes it as: Continual learning for enterprise AI. The founders listed are Regina Lin (Founder/CEO), Kevin Gu (Founder) (Y Combinator directory entry, January 18, 2025).
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Example from a real report (our sample on Target): “Target eliminated approximately 1,800 corporate positions, with around 1,000 employees receiving layoff notices and the remainder accounted for by eliminating open roles.” Source: NBC News
ThirdLayer is the learning and alignment layer for enterprise AI. We continuously ingest and structure messy organizational context, complex operational processes, and siloed, permission-sensitive data, then grade agents against the outcomes each company cares about. Every interaction becomes feedback that helps agents improve over time.
Companies use ThirdLayer to power their internal agents or embed it into the AI products they’re building. We give agents the context, evaluations, and learning loops they need to stay aligned with each organization and deliver better outcomes with every run.
Regina Lin
Founder/CEO
Kevin Gu
Founder
Founders, titles and bios as the company published them. Photographs are our own copies of the ones on that record, so they do not break when the original link expires.
One of 232 companies held here in B2B › Productivity.
No investor is drawn from a Form D — the form states how many invested and never who. The one investor on this graph is named because a batch has exactly one.
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Example from a real report (our sample on Target): “Target eliminated approximately 1,800 corporate positions, with around 1,000 employees receiving layoff notices and the remainder accounted for by eliminating open roles.” Source: NBC News
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What the Full Report on Thirdlayer covers
The Short Answer
Which Company This Is
What They Do, And How The Money Works
Who Runs It, And How To Reach Them
The Money: Funding, Valuation, Runway
Who Pays Them, And Who They Are Up Against
Warning Bells
Sources
1 cited source found
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