# PennyRail npm.latest — NPM Package Latest Version Lookup

> PennyRail npm.latest — NPM Package Latest Version Lookup is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Returns the latest published version of an npm package by name

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/f/npm.latest
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pennyrail-npm-latest-npm-package-latest-version-lookup-73c0bbce
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_u9CChcEE6Eaz6FroAGixD

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 pennyrail-npm-latest-npm-package-latest-version-lookup-73c0bbce -d '<json body>'
```

Example prompt: What is the latest published version of the 'axios' package on npm?

## When to prefer this

Use this endpoint when you need a quick, programmatic lookup of the latest npm package version without setting up npm CLI or registry API credentials. It is best suited for agents automating dependency checks, version pinning, or audit workflows at $0.001 USDC per call with x402 micropayment settlement.

## Known failure modes

- Package name not found on npm registry — returns error or null result
- Invalid or empty package name input — may return validation error
- npm registry upstream unavailability — may return timeout or 5xx
- Scoped package names (e.g. @org/pkg) may require special formatting
- Rate limiting or payment failure may block the request

## How this service works

Machine-readable settlement service

## Output

Returns a JSON object containing an 'operation' field describing the action performed and a 'result' field with the latest version information for the requested npm package, which may include the version string and associated package metadata.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "string",
   "description": "package name"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "operation",
  "result"
 ],
 "properties": {
  "result": {},
  "operation": {
   "type": "string"
  }
 },
 "additionalProperties": true
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pennyrail-npm-latest-npm-package-latest-version-lookup-73c0bbce/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from pennyrail.vercel.app](https://www.zero.xyz/host/pennyrail.vercel.app/llms.txt)