Coasty (YC S26) – An API for computer-use agents

Hey HN, we’re Nitish and Prateek, the founders of Coasty (https://coasty.ai/computer-use). We’re building computer-use agents that can complete workflows inside legacy desktop software and web applications without usable APIs.Developers send Coasty a natural-language task either through our consumer app or through our API, select a machine or browser environment, and any relevant credentials or files. The agent then operates the interface through screenshots, mouse, and keyboard input, verifies the result, and returns a structured run record with screenshots, actions, outputs, and errors.Here is a raw demo of an agent completing a workflow in a legacy application(It’s a mockup): https://drive.google.com/file/d/1ZghU_3vsAYhHVz1bsvE0pkvZYk7...A lot of important software is still difficult to automate. Healthcare teams submit prior authorizations through payer portals, accounting teams enter data into desktop applications, and operations teams move information between internal systems, spreadsheets, and remote desktops. Many of these applications have no API, incomplete APIs, or integrations that take months to build.The usual alternative is RPA, record a sequence of clicks and replay it. That works when the interface and workflow are predictable, but it often breaks when a button moves, a pop-up appears, a page loads slowly, or the application enters an unexpected state.Coasty takes a different approach. The agent observes the current screen, decides what action to take, executes it, and then observes the resulting state before continuing. It does not require DOM access, an accessibility tree, selectors, or an application-specific integration, so the same API can operate browsers, remote desktops, and older Windows applications.A simplified request looks roughly like this: run = coasty.runs.create( environment="vm_123", task=""" Open the patient record in the billing portal. Ente

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An API that lets AI agents automate workflows in legacy software by observing screens and controlling mouse/keyboard, replacing brittle RPA for systems without APIs.

The pain

Companies waste thousands of hours on manual data entry and workflow repetition across legacy desktop apps, healthcare portals, and internal systems that have no APIs or broken integrations. RPA solutions break constantly when UI elements shift or unexpected states occur. The alternative, building custom integrations, takes months and costs tens of thousands.

The gap

Current RPA tools require recording click sequences and break on any UI variation. Modern AI can see and reason about screens, but there's no standardized API layer that lets developers easily deploy agents against arbitrary applications without building custom connectors for each one.

Build angle

Start with healthcare prior authorization workflows and accounting data entry, high-volume, repetitive, painful, and locked in legacy systems. Prove the agent can handle real variability (pop-ups, slow loads, unexpected states) better than RPA. Build the API so it works across browsers, VMs, and Windows apps without requiring DOM access or selectors. Charge per successful task completion or monthly for high-volume users.

Strengths

  • Massive TAM: healthcare, finance, accounting, operations all have billions in manual labor trapped in legacy systems
  • Technical differentiation: vision-based agents are genuinely more robust than selector-based RPA when UI changes
  • No integration required: same API works across any application type (web, desktop, remote)
  • YC backing and founder credibility suggest technical execution capability
  • Clear use cases with measurable ROI (prior auth processing, invoice entry, data migration)

Risks

  • Agent reliability at scale: vision-based agents still hallucinate and get stuck; needs bulletproof error handling and human escalation
  • Regulatory friction: healthcare and finance workflows have compliance requirements; agents may not be acceptable for certain regulated tasks
  • Competitive response: Anthropic, OpenAI, and established RPA vendors (UiPath, Automation Anywhere) will build similar capabilities; timing matters
  • Customer acquisition: enterprise sales cycles are long; need to prove ROI on pilot before scaling
  • Pricing model unclear: per-task pricing may not align with customer budgets; could face resistance if costs exceed RPA alternatives
  • Hallucination liability: if agent makes errors (wrong patient record, wrong amount entered), who bears the cost?

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