# Space Kitty Archive API

Base URL: https://space-kitty.com · Premium price: $0.20 per request (x402, USDC on Base Sepolia (testnet), network eip155:84532).

## Endpoints

- `GET /api/v1` (free): API index: endpoints, pricing, payment terms, archive statistics.
- `GET /api/v1/domains` (free): Research domains with topic and paper counts.
- `GET /api/v1/topics` (free): All topics (filter with ?domain=). Params: domain.
- `GET /api/v1/topics/{slug}` (free): Topic overview: description, dossier preview, top and newest papers.
- `GET /api/v1/topics/{slug}/papers` (free): Ranked paper metadata for a topic, with abstracts where licensed. Params: sort=top|recent, limit (≤100), offset, kind.
- `GET /api/v1/search` (free): Full-text search over papers, trials and dossiers with highlighted snippets. Params: q, type=all|papers|dossiers, topic, kind, year_from, year_to, limit (≤50), offset.
- `GET /api/v1/papers/{id}` (free): One paper or trial record (ids like arxiv:2408.13687, doi:10.1038/…, nct:NCT05000000).
- `GET /api/v1/latest` (free): Newest additions across all topics. Params: topic, limit (≤50).
- `GET /api/v1/dossiers` (free): Dossier catalog with summaries, statistics and prices. Params: domain.
- `GET /api/v1/dossiers/{slug}/preview` (free): Free dossier preview: summary, contents, statistics, verification record, sample claims.
- `GET /api/v1/dossiers/{slug}` ($0.20): Full dossier: Markdown body, structured claims with citations, timeline, benchmarks, open problems, glossary, resolved bibliography. Send Accept: text/markdown for Markdown.
- `GET /api/v1/topics/{slug}/pack` ($0.20): Research pack: the topic dossier plus the 50 most influential and 25 newest papers (with licensed abstracts) and related trials, in one JSON document.
- `POST /mcp` (free): Model Context Protocol endpoint (Streamable HTTP, JSON responses). Free search tools; paid tools settle via x402.

## Paying

1. Request a premium URL and receive `402` with a base64 JSON `PAYMENT-REQUIRED` header (x402 v2). The JSON body repeats the terms in v1 format (`accepts`).
2. Sign an EIP-3009 USDC authorization for `accepts[0]` and retry with `PAYMENT-SIGNATURE` (v2) or `X-PAYMENT` (v1).
3. On success you get `200`, a `PAYMENT-RESPONSE` header (settlement tx) and `X-Archive-Receipt` (free re-download of the same resource for 24h).

Nothing is charged for 404s, errors or failed settlement.

MCP: https://space-kitty.com/mcp (Streamable HTTP). Paid tools accept payment in `params._meta["x402/payment"]`.
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Space Kitty Archive · https://space-kitty.com · API: https://space-kitty.com/api/v1 · MCP: https://space-kitty.com/mcp · Premium: $0.20/request via x402 (Base Sepolia (testnet)). Metadata: arXiv (CC0), OpenAlex (CC0), Europe PMC (CC BY/CC0 works), ClinicalTrials.gov.