# Paket Runtime Compatibility Checker

> Paket Runtime Compatibility Checker is a paid API for AI agents from paket.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-15).

Normalises and evaluates package runtime compatibility declarations (engines, os, cpu, Python classifiers) to determine where an npm or PyPI package can run.

## Facts

- Endpoint: POST https://paket.halowerk.com/v1/runtime-compat
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/paket-runtime-compatibility-checker-ee8af7f3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_I4KtbRnb6vuM5TzQJC8FP

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability paket-runtime-compatibility-checker-ee8af7f3 -d '<json body>'
```

Example prompt: Check the runtime compatibility declaration for numpy 1.26.4 on PyPI — I need to know which Python versions, operating systems, and implementations it officially supports, including any classifiers it declares.

## When to prefer this

Use this endpoint when you need a normalised, structured view of what a specific package version officially declares about where it can run — across OS, CPU architecture, Node/Python version, and implementation. Prefer it over generic package metadata endpoints when the specific concern is runtime compatibility gating (e.g. CI matrix checks, deployment environment validation, cross-platform dependency audits). It handles the ecosystem-specific field differences between npm and PyPI so you don't have to.

## Known failure modes

- Package or version not found in the target registry — returns 404 or equivalent error
- Unsupported ecosystem provided — returns validation error
- Package publishes no runtime compatibility fields — returns empty or null fields for those dimensions
- Registry API timeout or unavailability — returns upstream error
- Malformed package name or version string — returns parse error

## How this service works

Normalises what a package version declares about where it can run. For npm that is the engines, os and cpu fields plus the declared package type and whether native build scripts are present; for PyPI it is requires_python together with the operating system, implementation and Python version classifiers.

## Output

A normalised runtime compatibility profile for the specified package version, including: for npm — the engines constraints (Node.js, npm version ranges), declared OS and CPU architecture support, package type (ESM/CJS), and whether native build scripts (install/preinstall) are present; for PyPI — the requires_python specifier and all relevant classifiers covering operating system, Python implementation, and Python version.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "name": {
   "type": "string",
   "maxLength": 300,
   "minLength": 1
  },
  "system": {
   "enum": [
    "npm",
    "pypi"
   ],
   "type": "string",
   "description": "Only npm and PyPI declare these fields machine-readably."
  },
  "version": {
   "type": "string",
   "maxLength": 60,
   "description": "Defaults to the latest version."
  },
  "target_os": {
   "type": "string",
   "maxLength": 30,
   "description": "linux, darwin, win32 …"
  },
  "target_arch": {
   "type": "string",
   "maxLength": 20,
   "description": "x64, arm64 …"
  },
  "target_runtime": {
   "type": "string",
   "maxLength": 40,
   "description": "Your runtime version, e.g. 20.11.1 for Node or 3.11 for Python."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/paket-runtime-compatibility-checker-ee8af7f3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from paket.halowerk.com](https://www.zero.xyz/host/paket.halowerk.com/llms.txt)