---
title: "Creates one run per leaderboard of the benchmark, each evaluating the same explicit list of
 matchup configurations."
method: POST
path: "/benchmark/{benchmarkId}/runs/custom"
tags: ["Benchmark"]
---

# Creates one run per leaderboard of the benchmark, each evaluating the same explicit list of
 matchup configurations.

`POST /benchmark/{benchmarkId}/runs/custom`

Answers 202 with one entry per created run and the seed they all share, so every leaderboard
 evaluates identical image pairs; a seed is generated when none is supplied. Hidden
 leaderboards and leaderboards excluded from the benchmark overall are left out. See
 POST /leaderboard/{leaderboardId}/runs/custom for how configurations are validated
 and resolved.

## Path parameters

- `benchmarkId` string, required

## Request body

- CreateBenchmarkCustomRunsEndpointInput
  - `name` string, required — The display name given to every created run.
  - `matchups` MatchupConfig[], required — The matchup configurations to evaluate, 1 to 2000 of them.
    - `participantIds` string[], nullable
    - `tags` string[], nullable
    - `promptIdentifiers` string[], nullable
    - `sampleIds` string[], nullable
    - `responses` integer, required
  - `seed` integer, nullable — Optional seed for deterministic matchup selection, applied to every created run. Omit to have one generated, which still keeps the runs aligned with each other.

## Response `202`

Accepted

- CreateBenchmarkCustomRunsEndpointOutput
  - `runs` CreateBenchmarkCustomRunsEndpointOutputRun[], required — The created runs, one per leaderboard.
    - `leaderboardId` string, required
    - `runId` string, required
  - `seed` integer, required — The seed every created run shares.

## Other responses

- `400` — Bad Request
- `401` — Unauthenticated
- `403` — Forbidden

## Changes

- **2026-08-27** `4ee3e6f5e4f4` — 1 info
  - endpoint added

[Change history](https://skmtc.dev/rapidata/apis/rapidata-api/changes/benchmark/:benchmarkId/runs/custom/post.md)

---

[API](https://skmtc.dev/rapidata/apis/rapidata-api.md) · [All operations](https://skmtc.dev/rapidata/apis/rapidata-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/rapidata/rapidata-api/revisions/4ee3e6f5e4f4/schema)