# PennyRail URL Resolve & Join

> PennyRail URL Resolve & Join is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Resolves and joins URL segments into a canonical, fully-formed URL string

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/p/nano/url.resolve--join-url
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pennyrail-url-resolve-join-83ded167
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_2Sz2BuIRJDcoCDxDqwXTW

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-url-resolve-join-83ded167 -d '<json body>'
```

Example prompt: Can you resolve this relative path '/docs/getting-started' against the base URL 'https://example.com/api/' to give me the full canonical URL?

## When to prefer this

Choose this endpoint when you need a lightweight, pay-per-call URL resolution and joining utility without setting up your own URL parsing logic. Particularly useful in agent pipelines that encounter relative links from scraped or crawled content and need to normalize them to absolute URLs on the fly. Prefer over general-purpose HTTP libraries when you want a serverless, metered microservice approach costing $0.001 USDC per call.

## Known failure modes

- Invalid or malformed base URL returns an error response
- Missing required 'input' field causes a 400-level error
- Relative path that cannot be resolved against the given base may return an error or unexpected result
- Network/service downtime on the Vercel deployment returns a 5xx error
- Payment not settled via x402 protocol results in a 402 Payment Required response

## How this service works

Machine-readable settlement service

## Output

Returns a fully resolved, canonical URL string produced by resolving and joining the provided URL segments or base+relative URL pair. Response is a JSON object containing the resulting URL.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "additionalProperties": true
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pennyrail-url-resolve-join-83ded167/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)