> ## Documentation Index
> Fetch the complete documentation index at: https://strella-7d79fa26-mintlify-8c581790.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Send Metadata to Strella or Redirect URLs via Parameters

> Pass participant IDs, campaign tags, and analytics values via your Strella study link — capture them in Strella or forward to an external destination.

When you share a Strella study link, you can append URL parameters to carry metadata — participant identifiers, campaign tags, cohort labels, or analytics tracking values — through the interview flow. Strella supports two distinct modes: capturing that metadata inside Strella for later analysis, or forwarding it to an external redirect URL so your downstream systems receive it automatically after the interview ends.

## Study URL Format

Every Strella study has a unique public share link generated when you publish your project. The base format is:

```text theme={null}
https://app.strella.io/onboard/{TOKEN}
```

For example:

```text theme={null}
https://app.strella.io/onboard/abcd1234
```

Find this link by clicking the **Share** button in the upper-right corner of your study dashboard.

## Mode 1: Capture Metadata in Strella

Use standard URL parameter names (without any prefix) when you want Strella to store the values internally and associate them with the participant's record.

**Example parameters:**

* `user_id=abcd-1234-efgh-5678`
* `source=cohort202602`

**Full URL example:**

```text theme={null}
https://app.strella.io/onboard/abcd1234?user_id=abcd-1234-efgh-5678&source=cohort202602
```

When a participant opens this link, Strella captures:

| Parameter | Value                 |
| --------- | --------------------- |
| `user_id` | `abcd-1234-efgh-5678` |
| `source`  | `cohort202602`        |

These values are stored with the participant's record in Strella so you can filter or reference them during analysis.

## Mode 2: Forward Metadata to an External URL

Use this mode when you want metadata passed to an external system after the interview ends — for example, to credit a panel provider or trigger a downstream workflow.

<Note>
  Forwarding requires **Redirect to URL** to be configured in your study settings. Strella appends the forwarded parameters to that destination URL after the participant finishes their call. See [Redirect Participants After Interview](/recruiting/redirect-participants) for setup steps.
</Note>

To forward metadata, add the `forward_` prefix to each parameter name in your study link. Strella strips the prefix before appending the parameters to the redirect destination.

**Example parameters:**

* `forward_user_id=abcd-1234-efgh-5678`
* `forward_source=cohort202602`

**Full study link example:**

```text theme={null}
https://app.strella.io/onboard/abcd1234?forward_user_id=abcd-1234-efgh-5678&forward_source=cohort202602
```

**How parameters are forwarded:**

| Parameter in study URL | Forwarded as on redirect URL |
| ---------------------- | ---------------------------- |
| `forward_user_id=...`  | `user_id=...`                |
| `forward_source=...`   | `source=...`                 |

**If your Redirect to URL is configured as:**

```text theme={null}
https://customer-redirect-url.com/call-completed
```

**Then Strella redirects the participant to:**

```text theme={null}
https://customer-redirect-url.com/call-completed?user_id=abcd-1234-efgh-5678&source=cohort202602
```

## End-to-End Example

The table below traces a full forwarding flow from the link you share to the URL the participant lands on after finishing the call.

| Stage                                                   | URL                                                                                                       |
| ------------------------------------------------------- | --------------------------------------------------------------------------------------------------------- |
| **Shared with participant**                             | `https://app.strella.io/onboard/abcd1234?forward_user_id=abcd-1234-efgh-5678&forward_source=cohort202602` |
| **Participant completes interview → Strella redirects** | `https://customer-redirect-url.com/call-completed?user_id=abcd-1234-efgh-5678&source=cohort202602`        |

## Best Practices

<Accordion title="URL-encode values with special characters">
  If a parameter value contains spaces, ampersands, or other special characters, URL-encode them before adding them to the link. For example, a space becomes `%20` and an ampersand becomes `%26`. Most link-building tools handle this automatically, but verify if you're constructing URLs by hand.
</Accordion>

<Accordion title="Avoid passing raw PII in query strings">
  Query strings are logged in browser history, server access logs, and analytics tools. Avoid placing sensitive personal information — full names, email addresses, government IDs — directly in URL parameters. Use opaque identifiers or hashed values instead.
</Accordion>

<Accordion title="Use stable, consistent IDs">
  Use IDs that remain constant for a given participant across sessions — such as a CRM ID or a hashed email — rather than ephemeral values. Stable IDs make it much easier to join Strella data with your external systems reliably.
</Accordion>

<Accordion title="Combining capture and forwarding">
  You can mix both modes in a single link. Parameters without the `forward_` prefix are captured in Strella; parameters with the prefix are forwarded to the redirect URL. Both sets can appear in the same query string.

  ```text theme={null}
  https://app.strella.io/onboard/abcd1234?user_id=abcd-1234-efgh-5678&forward_source=cohort202602
  ```

  In this example, `user_id` is stored in Strella and `source` is forwarded to the redirect destination.
</Accordion>