Show HN: Sandbox AI-app lifecycle, from build to run

Public Alpha - macOS only (for now) Free to use

Build, run, test, and share AI apps
— sandboxed from build to run.

When you tell an agent
what to build,
you inherit how it built it.

AI apps quietly become your responsibility. Most tooling only sandboxes the runtime, completely ignoring the risky, messy parts before it.

The Definition

What Is an "AI app"?

It's a user-facing or agent-facing product with AI functionality. With CapaKit, it becomes a self-contained, sharable AI app Kit.

Standalone Web Interfaces Applications that ship entirely with their own built-in web UI.

Agentic Integrations Tools that plug directly into your agents via MCP or skills.

Why CapaKit?

AI apps come with burdens that quietly land on you.
CapaKit makes them explicit by default.

Security

Managing secrets, permissions, and blocking unwanted network access.

Handled by default and tailored for each app minimal needs.

Testing

Making sure code, logic, and agent flows work reliably end-to-end.

Structured testing from a service to full integration tests, run in isolation.

Deployment

Wiring up network endpoints, resolving dependencies, and manual installs.

Point CapaKit to a GitHub source, .capakit archive, or unpacked Kit folder.

Built for the Agentic Stack

MCP

A2A

OpenAI-compatible APIs

Skills

CapaKit natively speaks the protocols your agents already use. The same manifest runs locally today — and is designed to run anywhere tomorrow.

How It Works

One command flow. Sandboxed from build to run. No setup ceremony.

Create a Kit

Tell your coding agent to use capakit and describe the app you want in plain product terms.

Example agent prompt:

Use capakit to create a new Kit called invoice-helper.

I want a web UI where I can upload invoice text and see extracted fields: vendor, date, total, and line items.

Add a HubSpot CRM integration. First ask me to confirm the extracted invoice details are correct, then use the HubSpot API client to enter them.

Expose the same workflow as a Codex skill I can install and use.

Add tests and leave clear run instructions.

Explore Demo AI app Kits

Built with CapaKit. Runnable with a single command straight from GitHub.

Created a useful Kit?

Submit a PR to feature your AI app Kit in the official Registry and share it with the community.

View Kit Registry ↗

AI app Kit Anatomy

An AI app Kit is the unit teams can standardize on.

CapaKit Philosophy

Local-first You build it, you own it. You can run it anywhere any time, even offline.
Agent-native Designed from the ground up to be driven, written, and understood by coding agents.
Isolation by default Isolation is treated as a first-class concern, not an afterthought.

CapaKit - Securely Build and Run AI Apps with Coding Agents

When you tell an agent what to build, you inherit how it built it.