# For AI and developers

> Free, read-only JSON API and MCP server for Catamaran Index charter prices, with sources and dates. Endpoints, MCP setup, limits and attribution.

URL: https://catamaranindex.com/developers/
Last updated: 2026-10-28
Author: Catamaran Index editorial team

Our charter price data is open to AI assistants, apps and researchers: a **static JSON API** and an **MCP server** that Claude, ChatGPT and other MCP clients can call. Both are free, read-only and need no key. They return the same figures as the pages, each with its source URL, the date we checked it and the catamaranindex.com page to cite.

## JSON API

Plain JSON files, regenerated every time we publish. No key, no limits, CORS open to any origin, cached for a day.

| File | What it holds |
|---|---|
| [/api/index.json](https://catamaranindex.com/api/index.json) | Self-description: endpoints, MCP details, attribution terms, data dates |
| [/api/destinations.json](https://catamaranindex.com/api/destinations.json) | One summary per destination: price range, cheapest and priciest month, licence, links |
| `/api/destinations/{slug}.json` | Everything on one destination: monthly catamaran prices, season, licence rules, weather, cost table, sources ([example: Croatia](https://catamaranindex.com/api/destinations/croatia.json)) |
| [/api/months.json](https://catamaranindex.com/api/months.json) | For each month, every area ranked cheapest first, with our season label and weather |
| [/api/best-time.json](https://catamaranindex.com/api/best-time.json) | When to go, per destination: the direct answer, best-value, best-weather and sweet-spot months, months to avoid |
| `/api/best-time/{slug}.json` | The full best-time answer for one destination: 12 months of price, temperature, wind and verdicts, who should go when, rules and sources ([example: Greece](https://catamaranindex.com/api/best-time/greece.json)) |
| [/api/fishing.json](https://catamaranindex.com/api/fishing.json) | Fishing on a charter, per destination: the direct answer, licence needed, cost, catch limits and notable species |
| `/api/fishing/{slug}.json` | Full fishing rules for one destination: licence, limits, protected areas, spearfishing, species with IUCN status, spots, charter-guest rules, gaps and sources, each fact labelled official, secondary, unconfirmed or not verified ([example: Croatia](https://catamaranindex.com/api/fishing/croatia.json)) |
| [/api/sources.json](https://catamaranindex.com/api/sources.json) | Every source with its URL and the date we checked it |
| [/data/prices-2026-10.csv](https://catamaranindex.com/data/prices-2026-10.csv) | The same monthly prices as CSV |

Slugs: `croatia`, `greece`, `bvi`, `bahamas`, `turkey`, `italy`, `balearics`, `thailand`, `french-polynesia`, `belize`.

```
curl https://catamaranindex.com/api/destinations/croatia.json
```

## MCP server

URL: **`https://catamaranindex.com/mcp`** (Streamable HTTP, stateless, JSON responses, no authentication). Tools:

- **`search_destinations`**: Find yacht or catamaran charter destinations, cheapest first, with average weekly prices in EUR from cited, dated public sources. Optional month, boat type and maximum weekly price. Each result has the source URL and check date, the canonical catamaranindex.com page and a booking link.
- **`get_destination`**: Everything Catamaran Index has on one destination: monthly catamaran prices, annual sailboat averages where sourced, cost table, season, licence rules, monthly air temperature and wind, sample route, all sources with dates and the canonical page URL.
- **`cheapest_months`**: All 12 months for one destination, cheapest first: average weekly catamaran price, our season label, % above the cheapest month, air temperature and wind.
- **`compare_destinations`**: Compare 2 to 6 destinations side by side: price range, cheapest and priciest months, sailboat averages, licence summary, extra costs and weather, optionally for one month.
- **`best_time_to_sail`**: When to go: a direct answer with the best-value months (cheapest), best-weather months, sweet spot and months to avoid, with average weekly catamaran prices (EUR), mean air temperature and wind per month, hurricane or wet-season notes, who should go when (budget, families, wind), the rules used, sources with dates, the canonical page URL and a booking link.
- **`fishing_rules`**: Can charter guests fish, and under what rules: a direct answer, whether a fishing licence is needed and its cost, catch limits, spearfishing rules, protected and no-take areas, species with scientific name, method, best months, IUCN status and endemism, spots, and charter-guest specifics. Every fact carries a status (official, secondary, unconfirmed or not_verified) and sources with dates; gaps are listed, not filled.
- **`list_sources`**: Every public source Catamaran Index uses, with URL, the date we checked it and notes.

Every tool result carries source URLs and dates, the canonical catamaranindex.com URL and, where it applies, a booking link. `best_time_to_sail` returns the same answer as the [best time to charter](https://catamaranindex.com/best-time/) pages, word for word; it accepts a slug or a name (e.g. "Croatia", "Tahiti"). `fishing_rules` returns the same answer as the [fishing pages](https://catamaranindex.com/fishing/), with each fact labelled `official`, `secondary`, `unconfirmed` or `not_verified`.

**Claude (web, desktop, mobile):** Settings → Connectors → Add custom connector, then paste the URL above. In **Claude Code**:

```
claude mcp add --transport http catamaranindex https://catamaranindex.com/mcp
```

**Claude Desktop config file**, for versions without custom connectors (uses the `mcp-remote` bridge):

```
{
  "mcpServers": {
    "catamaranindex": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "https://catamaranindex.com/mcp"]
    }
  }
}
```

**ChatGPT and other clients:** add a custom MCP connector (in ChatGPT this needs developer mode) with the URL above and no authentication. Client menus change often, so check your client's help page if a step differs.

## Limits

- **/mcp:** about 60 requests per minute per IP; more returns HTTP 429 with a `Retry-After` header. Requests over 32 KB are refused. Identical tool calls may be served from cache for up to an hour.
- **JSON files:** no limit. For bulk use, download them instead of calling /mcp in a loop.
- The service runs on a free hosting tier with a daily cap, so /mcp can be unavailable for the rest of a day (UTC) after heavy use. The JSON files are not affected.

## Attribution and terms

- **Cite us:** name **Catamaran Index** and link to the `canonical_url` that comes with each figure, and name the original source listed with it (for example "12 Knots, checked 27 Oct 2026").
- **Third-party data:** figures come from the public sources listed with them, which keep their own rights. We grant no licence over their data.
- **Weather:** our calculation from [NASA POWER](https://power.larc.nasa.gov/) data. Credit NASA POWER when you reuse it: "The data was obtained from NASA Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) Project funded through the NASA Earth Science Division."
- **Our arithmetic** (season labels, min/max/mean, % above the cheapest month) is marked `derived` in the data.
- **Affiliate links:** `book_url` goes through `/go/samboat`; we may earn a commission on bookings at no extra cost to the traveller ([disclosure](https://catamaranindex.com/affiliate-disclosure/)).
- **Gaps stay gaps:** where we have no verified figure (motor yachts, gulets, crewed charters, monthly monohull prices), the API says so and returns nothing.

How the numbers are collected: [methodology](https://catamaranindex.com/methodology/). Questions or errors: [contact](https://catamaranindex.com/contact/).

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Affiliate disclosure: some links are affiliate links; we may earn a commission at no extra cost to you. See /affiliate-disclosure/.