---
title: "Get Event Similar"
method: GET
path: "/api/v1/events/{source}/{event_id}/similar"
tags: ["events"]
---

# Get Event Similar

`GET /api/v1/events/{source}/{event_id}/similar`

## Request

- Base URL: `https://api.pdata.world`
- URL: `https://api.pdata.world/api/v1/events/{source}/{event_id}/similar`
- Auth: none declared

Use when an agent needs events similar to a given event — cross-platform equivalents and topically-related markets, precomputed nightly from title embeddings. Best-first; empty list (never an error) when no similarities are known yet.

## Path parameters

- `source` string, required: Platform id, e.g. kalshi.
- `event_id` string, required: Event id native to the source.

## Query parameters

- `limit` integer: Max similar events to return.

## Response `200`

Successful Response

- EventSimilarOut
  - `source` string, required
  - `event_id` string, required
  - `excluded` boolean
  - `similar` SimilarItemOut[]
    - `source` string, required: Venue of the similar event.
    - `id` string, required: The venue's event id; pdata's page is https://pdata.world/events/{source}/{id}.
    - `title` string, nullable: Event title as the venue publishes it.
    - `prob` number, nullable: Live probability of the event's leading market (`top_outcome`), or of its single market, in [0, 1]. Null when there is none; see `lead`.
    - `prob_24h_change` number, nullable: 24-hour change in the leading market's probability, as a fraction on the [0, 1] scale (0.05 = up 5 percentage points).
    - `volume_24hr` number, nullable: The event's venue-reported 24h volume, in the venue's own unit (shares for Polymarket, contracts for Kalshi, mana for Manifold); not comparable across venues.
    - `score` number, required: Cosine similarity of the two events' title embeddings, 0-1, higher is closer. Recomputed nightly.
    - `is_cross_platform_equiv` boolean: True when pdata judges it to ask the same question on another venue: different venue, similarity >= 0.85, end dates within 3 days, and no clash of years or numeric thresholds in the titles. A heuristic, not a guarantee; compare the titles.
    - `lead` string, nullable: Leading outcome's label, set only when `prob` is null.
    - `markets` SimilarMarketMini[]: Up to 3 of the event's markets, open first, then by 24h volume. Empty for group events, whose markets sit one level down.
      - `name` string, nullable: The market's outcome label.
      - `prob` number, nullable: Probability, in [0, 1].
      - `prob_24h_change` number, nullable: 24-hour change in `prob`, as a fraction on the [0, 1] scale (0.05 = up 5 percentage points).
    - `market_count` integer: Number of the event's own markets (0 for group events).
  - `_meta` ResponseMetaList: Agent metadata for list/aggregate responses (no cite_as).
    - `attribution` string: Who aggregated this data, under which licence, and whose data it is.
    - `canonical_url` string, required: Stable URL for this resource: the pdata.world page, or the API URL for list responses.
    - `as_of` string, date-time: When this response was generated (UTC).
    - `docs` string: API documentation.

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/pdata/apis/pdata-backend.md) · [All operations](https://skmtc.dev/pdata/apis/pdata-backend/llms.txt) · [OpenAPI document](https://skmtc.dev/pdata/apis/pdata-backend/revisions/4c9bf3856786?raw)