Y Combinator invests in Coasty

Decision brief

What changed

Y Combinator's S26 batch includes Coasty, a startup that launched an API enabling computer-use agents to automate workflows in legacy software by observing screenshots and controlling mouse/keyboard input, without requiring API or DOM access. The product runs in isolated VMs and includes state tracking, invariant checking, human approval gates, and audit trails, with pricing tied to agent runtime and workflow volume.

Why it matters

This offers a route to automate legacy systems (e.g., healthcare prior authorization) that lack modern APIs, potentially unlocking automation in industries with entrenched, hard-to-integrate software. The inclusion of approval gates and audit trails signals an attempt to address enterprise concerns around control and compliance for autonomous agents acting on production systems, which matters for organizations evaluating build-vs-buy on RPA/agent automation and for risk owners assessing new attack surfaces or failure modes in legacy workflows.

Affected roles

COO CTO CISO

Evidence

The only source is a single Launch HN post announcing the YC S26 startup, so claims about features and use cases are self-reported by the company with no independent verification or third-party coverage.

What remains uncertain

It is unverified how the invariant checking and approval gates perform in practice, what failure rates or error-recovery mechanisms exist, and whether the tool has any paying customers or production deployments beyond the stated use case examples; scale, security posture, and real-world reliability remain unknown.

Monitor next

Watch for independent case studies, customer testimonials, or security audits of Coasty's agent-in-VM approach as it moves beyond launch announcement into production use.

Analytical support, not advice — assumptions and open questions stated above.

Source coverage