# Gutenberg Books by Topic Search

> Gutenberg Books by Topic Search is a paid API for AI agents from clonecho.builda.company, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-14).

Returns a list of public-domain books from Project Gutenberg that match a given topic or subject query.

## Facts

- Endpoint: POST https://clonecho.builda.company/x402/s/gutenberg-books-by-topic
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/gutenberg-books-by-topic-search-7c781be0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_phpFez8PiYSXBNKyfXjfd

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 gutenberg-books-by-topic-search-7c781be0 -d '<json body>'
```

Example prompt: Can you find me a list of public-domain books from Project Gutenberg about the topic of 'stoicism'?

## When to prefer this

Use this endpoint when you need to discover public-domain books filtered by subject or topic (e.g., 'philosophy', 'adventure', 'women'), as opposed to searching by title or author name. Prefer this over the title/author sibling endpoint when the user knows a theme but not a specific book.

## Known failure modes

- Empty result set if topic is too obscure or misspelled
- Payment failure if USDC balance is insufficient (x402 protocol error)
- Ambiguous query returning unrelated books
- API timeout or server error returning non-200 status

## How this service works

Public-domain books from Project Gutenberg matching a topic/subject q. Query: ?q= Returns JSON.

## Output

A JSON array of public-domain book records from Project Gutenberg matching the specified topic/subject, likely including titles, authors, and download counts.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/gutenberg-books-by-topic-search-7c781be0/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from clonecho.builda.company](https://www.zero.xyz/host/clonecho.builda.company/llms.txt)