> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://humanloop.com/docs/v5/api/evaluations/add-existing-run/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://humanloop.com/_mcp/server.

# Add Existing Run

POST https://api.humanloop.com/v5/evaluations/{id}/runs/{run_id}

Add an existing Run to the specified Evaluation.

This is useful if you want to compare the Runs in this Evaluation with an existing Run
that exists within another Evaluation.

Reference: https://humanloop.com/docs/api/evaluations/add-existing-run

## Authentication

- `X-API-KEY` header (required) — API Key authentication via header

## Request

### Path parameters

- `id` (string, required) — Unique identifier for Evaluation.
- `run_id` (string, required) — Unique identifier for Run.

## Response

### 200

Successful Response

- `any`

## Errors

### 422 Add Existing Run Evaluations ID Runs Run ID Post Request Unprocessable Entity Error

Validation Error

- `detail` (list of ValidationError, optional)

## Types

### ValidationError

- `loc` (list of ValidationErrorLocItem, required)
- `msg` (string, required)
- `type` (string, required)

### ValidationErrorLocItem

## Examples

**Response**

```json
{
  "key": "value"
}
```

**SDK Code**

```python
import requests

url = "https://api.humanloop.com/v5/evaluations/id/runs/run_id"

headers = {"X-API-KEY": "<apiKey>"}

response = requests.post(url, headers=headers)

print(response.json())
```

```typescript
import { HumanloopClient } from "humanloop";

const client = new HumanloopClient({ apiKey: "YOUR_API_KEY" });
await client.evaluations.addExistingRun("id", "run_id");

```

```go
package main

import (
	"fmt"
	"net/http"
	"io"
)

func main() {

	url := "https://api.humanloop.com/v5/evaluations/id/runs/run_id"

	req, _ := http.NewRequest("POST", url, nil)

	req.Header.Add("X-API-KEY", "<apiKey>")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}
```

```ruby
require 'uri'
require 'net/http'

url = URI("https://api.humanloop.com/v5/evaluations/id/runs/run_id")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["X-API-KEY"] = '<apiKey>'

response = http.request(request)
puts response.read_body
```

```java
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;

HttpResponse<String> response = Unirest.post("https://api.humanloop.com/v5/evaluations/id/runs/run_id")
  .header("X-API-KEY", "<apiKey>")
  .asString();
```

```php
<?php
require_once('vendor/autoload.php');

$client = new \GuzzleHttp\Client();

$response = $client->request('POST', 'https://api.humanloop.com/v5/evaluations/id/runs/run_id', [
  'headers' => [
    'X-API-KEY' => '<apiKey>',
  ],
]);

echo $response->getBody();
```

```csharp
using RestSharp;

var client = new RestClient("https://api.humanloop.com/v5/evaluations/id/runs/run_id");
var request = new RestRequest(Method.POST);
request.AddHeader("X-API-KEY", "<apiKey>");
IRestResponse response = client.Execute(request);
```

```swift
import Foundation

let headers = ["X-API-KEY": "<apiKey>"]

let request = NSMutableURLRequest(url: NSURL(string: "https://api.humanloop.com/v5/evaluations/id/runs/run_id")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "POST"
request.allHTTPHeaderFields = headers

let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    print(error as Any)
  } else {
    let httpResponse = response as? HTTPURLResponse
    print(httpResponse)
  }
})

dataTask.resume()
```