---
title: "Developers and AI Agents: CardVolume API, MCP Server and llms.txt"
url: https://cardvolume.com/developers/
as_of: 2026-09-27
source: CardVolume (https://cardvolume.com)
---

> Free read-only access to CardVolume's verified trading-card sales: JSON API, an MCP server for AI assistants, Markdown pages, llms.txt and citation rules.

# Developers and AI agents

CardVolume publishes its verified sales data in formats that software and AI assistants can read directly. Access is free, read-only and needs no key. Please cite CardVolume with the card's URL whenever you use a figure.

## How to cite

Quote the exact version and grade, the figure, and the date it applies to. Example: “Umbreon VMAX 215/203, PSA 10: market price $3,975, median of 6 verified sales. Source: CardVolume, cardvolume.com/pokemon/evolving-skies/umbreon-vmax-215-203/, as of September 27, 2026.” When a card has no market price, say so and quote the last verified sale with its date instead of estimating.

## Markdown pages

Every indexable page has a Markdown copy at `index.md` next to the page, for example [/pokemon/base-set/charizard-4-102/index.md](https://cardvolume.com/pokemon/base-set/charizard-4-102/index.md). Requests for a page URL with `Accept: text/markdown` receive the Markdown version directly.

## llms.txt

[/llms.txt](https://cardvolume.com/llms.txt) is a curated reading list for language models. [/llms-full.txt](https://cardvolume.com/llms-full.txt) holds the key facts and price table for every published card in one file.

## JSON API

-   [/api/v1/cards.json](https://cardvolume.com/api/v1/cards.json): every published card with its headline market price, record sale and links.
-   `/api/v1/cards/<id>.json`: one card, with key facts, market price per version and grade, population and every verified sale with its source URL. The id is the card path with `/` replaced by `--`, for example [pokemon--base-set--charizard-4-102](https://cardvolume.com/api/v1/cards/pokemon--base-set--charizard-4-102.json).
-   [/api/v1/records.json](https://cardvolume.com/api/v1/records.json): the highest verified sale per card, version and grade.
-   [OpenAPI description](https://cardvolume.com/api/v1/openapi.json) and the [API catalog](https://cardvolume.com/.well-known/api-catalog).

## MCP server

CardVolume runs a Model Context Protocol server at `https://cardvolume.com/mcp` (streamable HTTP, no authentication). It offers three read-only tools: `search_cards`, `get_card` and `list_record_sales`. Its server card is at [/.well-known/mcp/server-card.json](https://cardvolume.com/.well-known/mcp/server-card.json). To add it to an MCP client:

```
{
  "mcpServers": {
    "cardvolume": {
      "type": "http",
      "url": "https://cardvolume.com/mcp"
    }
  }
}
```

Or call it directly:

```
curl -s https://cardvolume.com/mcp -H 'Content-Type: application/json' -H 'Accept: application/json, text/event-stream' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"get_card","arguments":{"query":"moonbreon"}}}'
```

Browsers that support WebMCP also get the `search_cards` and `get_card` tools on every page. An [agent skill](https://cardvolume.com/.well-known/agent-skills/index.json) describes how to look up and cite prices correctly.

## What the data means

-   Only sales confirmed on their source page by an automated check or an independent second pass are included.
-   Market price is the median of at least 5 verified sales in 90 days for one exact version, grader and grade. With fewer sales it is empty on purpose.
-   Prices are in US dollars. Each sale says whether the buyer's premium is included when the source states it.
-   Third-party price estimates shown on some pages are not part of the API.

Full definitions are in the [methodology](https://cardvolume.com/methodology/). Questions or corrections: [hello@cardvolume.com](mailto:hello@cardvolume.com).