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

# Using URL Parameters

> Prefill survey fields and candidate attributes by passing values through the study link.

URL parameters let you prefill survey fields and candidate attributes by passing values through a study link. This is handy when you're inviting people in bulk from an external platform and already know something about them, you can carry that data straight into their responses.

<Note>
  This is a different mechanism from the `gq_`-prefixed parameters used when embedding Great Question data into an *external* survey tool like Qualtrics. Those flow outward, from Great Question to the external tool. The parameters on this page flow inward, into Great Question's own study and screener pages.
</Note>

## When URL parameters work

Prefill works on **Invite via link** links, the generic, tokenless links you generate and share yourself. It's more limited on personalized links, like the ones sent in an email invite: those already point to a specific candidate's record, so name and email come from that existing record rather than the URL, any extra parameters on that kind of link are ignored.

You can pass:

* **name**
* **email**
* **phone\_number**
* **unique\_id**
* **referrer** — a single reserved field for capturing where a participant came from, stored on the candidate as a hidden value.
* **Any custom attribute** enabled for URL population.

<Note>
  There's no general UTM/campaign-parameter feature (`utm_source`, `utm_campaign`, and similar aren't supported) — `referrer` is the one built-in field for this. If you need more structured source tracking, use a custom attribute instead.
</Note>

## What you'll need

* Access to **Candidate Attributes**.
* An existing survey or screener.
* Attributes mapped to the relevant survey questions, if you want the value to show up in a survey field rather than just being stored on the candidate.

## Setting it up

1. In the **Survey editor**, map survey fields to the custom attributes you want to prefill.
2. Enable those attributes for URL population under **Settings → Custom Attributes** — look for **Can be set via a URL parameter**.
3. Construct your link with a query string. Separate parameters with `&`:
   ```text theme={null}
   https://greatquestion.co/...?plan=enterprise&name=PJ&email=support@greatquestion.co
   ```

<Tip>
  Use hidden fields for values you want to track but not show the participant, such as a campaign or source identifier.
</Tip>

## Troubleshooting

| Issue                                     | What's happening                                                                  | How to fix                                                                                    |
| ----------------------------------------- | --------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------- |
| Prefilled data isn't appearing            | The attribute isn't enabled for URL population, or isn't mapped to a question     | Enable it under **Settings → Custom Attributes** and confirm the mapping in the Survey editor |
| Values aren't being read                  | The URL is malformed                                                              | Check that parameters are joined with `&` and values are correctly formatted                  |
| Only name and email prefill, nothing else | The link is a personalized/email invite link tied to an existing candidate record | Use a generic **Invite via link** link instead if you need custom attributes to prefill       |
| Old values keep showing                   | A cached version of the link is loading                                           | Clear the cache or open the link in a fresh browser tab                                       |

***

**Still need help?** Contact us at [support@greatquestion.co](mailto:support@greatquestion.co) — median response time is 19 minutes during [support hours](https://greatquestion.co/features/about-our-support-team).