# Free Public-Domain Books on Siblings Subject

> Free Public-Domain Books on Siblings Subject is a paid API for AI agents from intel.rallylive.ca, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Returns a ranked, paginated catalogue of free public-domain books tagged with the Library of Congress 'Siblings' subject, with direct download links in epub/txt/html formats.

## Facts

- Endpoint: GET https://intel.rallylive.ca/library/subject/siblings
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/free-public-domain-books-on-siblings-subject-c0636533
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_B44fU7DVIAujUjKjeAhyG

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 free-public-domain-books-on-siblings-subject-c0636533
```

Example prompt: Can you find me free public-domain books about siblings I can download — ideally epub or txt format — from the Project Gutenberg catalogue?

## When to prefer this

Choose this endpoint when you need to discover or list free, legally downloadable public-domain books specifically about sibling relationships, with ready-to-use epub/txt/html links. Prefer it over generic web search when you need structured catalogue data with popularity ranking and verified download links from Project Gutenberg and Internet Archive.

## Known failure modes

- No results returned if keyword filter is too narrow or misspelled
- Rate limiting or payment failure if USDC micro-payment is not processed
- Occasional broken download links if upstream source (Project Gutenberg/Internet Archive) has moved or removed the file
- Empty result set for highly specific author+title combinations that don't match any siblings-tagged work

## How this service works

Free public-domain books on "Siblings": browse the catalogue's works tagged with that Library of Congress subject (467 in Project Gutenberg alone, plus Internet Archive scans), ranked by relevance and popularity, with direct epub/txt/html download links. Add words to narrow by title or author. Re-verified daily. $0.01 per page of 20.

## Output

A paginated list (20 items per page) of public-domain books tagged with the 'Siblings' Library of Congress subject, ranked by relevance and popularity, with direct download links in epub, txt, and html formats. Sourced from Project Gutenberg and Internet Archive, re-verified daily.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/free-public-domain-books-on-siblings-subject-c0636533/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from intel.rallylive.ca](https://www.zero.xyz/host/intel.rallylive.ca/llms.txt)