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Prediction markets

GET /predictions
ListPredictionMarkets

Browse Polymarket and Kalshi contracts. Prices are outcome probabilities from each venue, not social sentiment. Volume retains its venue unit. Equivalent contracts share a market; related contracts remain separate. Subject metrics use the existing subject and asset endpoints.

Wallet payment available at https://nebula-api.hiddensystems.ai/api/v1/x402/predictions. No Nebula account or API key required; check the payment offer before signing. x402 payment guide.

Parameters

query string QUERY

Case-insensitive search across public identifiers and names.

Example:NVIDIA

provider string QUERY

Optional venue

Allowed values
polymarketkalshi

Example:polymarket

status string QUERY

Defaults to open

Allowed values
openclosedresolveddisputedall

Default:open

subject_id string QUERY

Canonical non-asset identifier returned by /subjects or /search, such as text:jensen huang or handle:elonmusk. Accepted in any case. It cannot be combined with asset_id or asset_class.

Example:text:jensen huang

limit integer QUERY

Maximum results returned.

Default:25

offset integer QUERY

Pagination offset

Default:0

cURL Example

curl --request GET \
  --url 'https://nebula-api.hiddensystems.ai/api/v1/public/predictions' \
  --header 'X-API-Key: YOUR_API_KEY'

Responses

200 OK
400 Bad Request
401 Unauthorized
402 Credits used up; response includes renewal timing and purchased credit balance
403 Forbidden
404 Not Found
405 Method not allowed; the Allow header lists the supported method
429 Too Many Requests
500 Internal Server Error
503 Service Unavailable

Media type application/json

has_more
boolean required

True when another page is available after the returned records.

limit
integer required

Maximum records requested.

markets
array<object> required

Canonical markets, ordered by best activity rank within each venue. Venue volumes are not summed.
markets[].id
string required

Stable identity within this object type.

markets[].listings
array<object> required

Venue listings with separately retained rules and quotes.
markets[].listings[].closes_at
string (date-time) required

Venue trading close in UTC; not necessarily event occurrence or settlement.

markets[].listings[].event_id
string required

Venue event identifier, or empty if absent.

markets[].listings[].id
string required

Stable identity within this object type.

markets[].listings[].liquidity_usd
number (double) required

Venue-reported liquidity in US dollars; null when unavailable.

markets[].listings[].market_id
string required

Canonical market identity; equivalent venue listings share it.

markets[].listings[].observed_at
string (date-time) required

UTC time Nebula fetched this quote. Inspect freshness before comparing.

markets[].listings[].open_interest
number (double) required

Venue open contracts; null when unavailable.

markets[].listings[].opens_at
string (date-time) required

Venue opening time in UTC; null when unavailable.

markets[].listings[].outcomes
array<object> required

Ordered native outcomes with independent price evidence.

markets[].listings[].provider
string required

Venue: polymarket or kalshi.

markets[].listings[].provider_id
string required

Native venue market identifier.

markets[].listings[].provider_updated_at
string (date-time) required

Venue metadata update time; null when unavailable.

markets[].listings[].question
string required

Original contract question.

markets[].listings[].resolution_source
string required

Venue resolution source, or empty if absent.

markets[].listings[].resolves_at
string (date-time) required

Venue expected resolution time in UTC; null when unavailable.

markets[].listings[].result
string required

Venue settlement result; empty before a known result.

markets[].listings[].revision
string required

SHA-256 of question, rules, source, close and outcome orientation.

markets[].listings[].rules
string required

Full venue resolution rules.

markets[].listings[].source_url
string required

Original venue listing URL.

markets[].listings[].status
string required

Listing lifecycle: open, closed, resolved or disputed. For subjects: resolved or pending.

markets[].listings[].volume
number (double) required

Cumulative venue volume in volume_unit; null when unavailable.

markets[].listings[].volume_24h
number (double) required

Last 24-hour venue volume in volume_unit; null when unavailable.

markets[].listings[].volume_unit
string required

usd for Polymarket, contracts for Kalshi. These quantities cannot be added.

markets[].question
string required

Original contract question.

markets[].subjects
array<object> required

Linked subjects. Use their existing analytics endpoints separately; no market sentiment is inferred.
markets[].subjects[].fallback_image_urls
array<string> required

Ordered backend-resolved fallback icon candidates.

markets[].subjects[].image_url
string required

First backend-resolved subject icon candidate; empty uses fallbacks.

markets[].subjects[].name
string required

Canonical subject display name.

markets[].subjects[].role
string required

Question attachment role: entity, topic or place.

markets[].subjects[].status
string required

Listing lifecycle: open, closed, resolved or disputed. For subjects: resolved or pending.

markets[].subjects[].subject_id
string required

Canonical registry subject identifier; preserves existing asset or topic eligibility.

markets[].subjects[].types
array<string> required

Canonical subject types from the existing identity resolver.

offset
integer required

Number of matching records skipped.

{
  "has_more": false,
  "limit": 50,
  "markets": [
    {
      "id": "polymarket:123",
      "listings": [
        {
          "closes_at": "2026-10-07T20:00:00Z",
          "event_id": "event-123",
          "id": "polymarket:123",
          "liquidity_usd": 5000,
          "market_id": "polymarket:123",
          "observed_at": "2026-10-06T12:00:00Z",
          "open_interest": 100,
          "opens_at": "2026-10-01T00:00:00Z",
          "outcomes": [],
          "provider": "polymarket",
          "provider_id": "123",
          "provider_updated_at": "2026-10-06T12:00:00Z",
          "question": "Will NVIDIA close above $200 on October 7?",
          "resolution_source": "Official exchange close",
          "resolves_at": "2026-10-08T00:00:00Z",
          "result": "yes",
          "revision": "revision-hash",
          "rules": "Resolves Yes if the official closing price exceeds $200.",
          "source_url": "https://polymarket.com/event/example",
          "status": "open",
          "volume": 10000,
          "volume_24h": 1000,
          "volume_unit": "usd"
        }
      ],
      "question": "Will NVIDIA close above $200 on October 7?",
      "subjects": [
        {
          "fallback_image_urls": [],
          "image_url": "https://example.com/nvda.png",
          "name": "NVIDIA",
          "role": "entity",
          "status": "open",
          "subject_id": "eq:NVDA",
          "types": []
        }
      ]
    }
  ],
  "offset": 0
}