> ## Documentation Index
> Fetch the complete documentation index at: https://docs.agg.market/llms.txt
> Use this file to discover all available pages before exploring further.

# Look up markets by venue identifier

> Resolve a Kalshi ticker or Polymarket token_id to the full cross-venue cluster.

If you already hold a venue's own identifier, you can resolve it directly instead
of searching. Every lookup returns the full cross-venue cluster, and it works the
same whether the identifier belongs to the cluster anchor or to one of its members.

## Events

```bash theme={null}
curl "https://api.agg.market/venue-events?venue=kalshi\
&externalIdentifier=KXNBAGAME-26MAR15BOSLAL" \
  -H "x-app-id: $AGG_APP_ID"
```

`matchedVenueEvents[]` on each result lists the same event on every other venue.

## Markets

```bash theme={null}
curl "https://api.agg.market/venue-markets?venue=polymarket\
&externalIdentifier=512345" \
  -H "x-app-id: $AGG_APP_ID"
```

`matchedVenueMarkets[]` lists the same market on every other venue.

## Outcomes

```bash theme={null}
curl "https://api.agg.market/venue-market-outcomes?externalIdentifier=$TOKEN_ID" \
  -H "x-app-id: $AGG_APP_ID"
```

`matchedVenueMarketOutcomes[]` gives a `{ venueMarketId, venueMarketOutcomeId }` reference
pair for the counterpart outcome on each matched venue — IDs only, correctly aligned even
where the two venues frame the question in opposite directions. This endpoint does not
return the counterpart objects themselves: fetch them from `/venue-markets` using the
returned `venueMarketId` if you need labels, prices, or venue metadata.

## Rules

* **`venue` is required** for `/venue-events` and `/venue-markets`. It is optional for
  `/venue-market-outcomes`, where identifiers are globally unique.
* **Batch up to 20 identifiers** per request by repeating the parameter. Over 20
  returns `400`.
* **Unknown identifiers are omitted** from `data` rather than returned as nulls.
  Match responses back to your input by reading `externalIdentifier` on each item.

## Two limits worth knowing

**Kalshi outcome identifiers cover one side only.** Kalshi puts its ticker on the
Yes-side outcome; the No side has no identifier and cannot be looked up directly.
Fetch the market instead and read both outcomes from `venueMarketOutcomes[]`.

**Do not persist cluster ids as permanent keys.** When two clusters merge, members
are re-pointed onto the surviving anchor. The old id stays a valid event, but it is
no longer the cluster head. Re-resolve from discovery, or key your own storage on
the venue identifier you already hold — that one is stable.