Market Registry API

The Market Registry API returns the events and markets Chainlink resolves: each market's identity, classification, and resolution criteria, and each event's status. The API is read-only and catalog-only. It does not return outcomes or a per-market status.

Endpoints

Base URL: https://markets.api.chain.link

Data responses are JSON over HTTPS. Markets exist only inside their event's markets array; there is no endpoint for a single event or market.

Authentication

Send your API key in the Authorization header with the ApiKey prefix. Every endpoint, including the OpenAPI document, uses the same key.

Terminal

export MARKETS_API_URL='https://markets.api.chain.link/user/v1'
export MARKETS_API_KEY='YOUR_API_KEY'

curl --header "Authorization: ApiKey ${MARKETS_API_KEY}" "${MARKETS_API_URL}/taxonomies"

Keys are issued by the Chainlink team to an organization with Prediction Markets access enabled.

List taxonomies

GET /user/v1/taxonomies returns the distinct category, sub-category, and grouping combinations that you can use as filters on /events. A grouping is a league or competition code, such as mlb.

Example response

Response

{
  "taxonomies": [
    { "category": "sports", "sub_category": "baseball", "grouping": "mlb" },
    { "category": "sports", "sub_category": "soccer", "grouping": "mls" }
  ],
  "total": 2,
  "limit": 100,
  "offset": 0
}

Entries are sorted by category, then sub_category, then grouping. They come from Chainlink's configured coverage, not from existing events: a combination can appear before any of its events exist, and events can remain after coverage ends. Use the entries to build filters, not to confirm that events exist.

List events

GET /user/v1/events returns events with their markets.

Query parameters

How the date range works:

• from and to select whole UTC days. Set them to the same date to select one day.
• An event matches when its scheduled_start falls in the range.
• Events with no scheduled start, such as a championship waiting on its deciding round, are always included and sorted after dated events. total counts them.
• Events are sorted by scheduled_start, earliest first. There is no sort parameter.

Example request

Terminal

curl --header "Authorization: ApiKey ${MARKETS_API_KEY}" \
  "${MARKETS_API_URL}/events?from=2026-08-20&to=2026-08-23&grouping=mlb&market_type=moneyline"

Example response

Response

{
  "events": [
    {
      "category": "sports",
      "sub_category": "baseball",
      "grouping": "mlb",
      "event_type": "match",
      "event_status": "scheduled",
      "name": "Yankees vs Orioles",
      "slug": "cl-sports-baseball-mlb-260820-nyan",
      "scheduled_start": "2026-08-20T23:05:00Z",
      "markets": [
        {
          "name": "Will New York Yankees win?",
          "slug": "cl-sports-baseball-mlb-260820-nyan-winner-nyan",
          "hash": "cb3ef6b22d09a15c8843765cb36c1c90fff2923caa3c4334ae375aeaf86c8e49",
          "market_type": "moneyline",
          "resolution_criteria": "Resolves YES if the New York Yankees win according to SportsDataio and OddsPapi."
        }
      ]
    }
  ],
  "total": 1,
  "limit": 100,
  "offset": 0
}

Response fields

Event types

Market types

Resolution criteria

resolution_criteria is built from the market's question:

• A question that starts with Will becomes Resolves YES if the …. Other questions keep their wording.
• When the event has data providers, the sentence ends with according to and their names, such as SportsDataio, OddsPapi, or Sportmonks.
• When a tie pays out 50/50, it adds In the event of a tie the market resolves 50/50.
• Weather markets return their rules text as written.

The string is a display summary, not a complete rulebook, and its wording can change. Use slug to identify a market, not this text.

Identifiers

• A market's slug is its identifier. It never changes, so use it to match a market across requests.
• hash is an alias of slug, not a second identifier. Recompute it to check a stored value: printf '%s' "$SLUG" | shasum -a 256.
• Treat a slug as opaque. Read it from the response; do not build it from name or other fields.
• The date in an event slug is part of the identifier, not the schedule. A rescheduled event keeps its slug. Read scheduled_start for timing.
• A change to a market's line can publish a new market with a new slug.

OpenAPI document

GET /user/v1/openapi.yaml returns the OpenAPI 3.0 document for this API as application/yaml, for code generation and API tools. GET /user/v1/openapi returns the same document as text/plain, so a browser displays it instead of downloading it.

Terminal

curl --header "Authorization: ApiKey ${MARKETS_API_KEY}" \
  "${MARKETS_API_URL}/openapi.yaml" --output openapi-user.yaml

Errors

Versioning

The version is part of the path: /user/v1. Ignore fields and values you do not recognize, so new fields and enum values do not break your integration.