What is tpuid?
A tpuid (for Third Party Unique ID) is a special parameter you can pass in survey URL to prevent duplicate participation, when you use external system for invitation send-out and it is not possible to use personal links.
When a respondent opens the survey, Survalyzer uses the provided tpuid value to identify their interview. Respondents who have already started the survey can use the same link to return to their existing interview. Once the interview is completed, the same value prevents them from starting another one.
External systems may include CRM, marketing automation, or HR platforms.
The external system used to send the invitations should automatically populate the tpuid value for each respondent.
Example link:
https://education.survalyzer.eu/lrguegvprz?l=en&tpuid=ABC123tpuid is one of several methods available in Survalyzer to help prevent multiple participation. It is most useful when you distribute a survey through an external system and still want each respondent to participate only once when using the specific link. Read more.
When Do You Need tpuid
Use tpuid when you distribute a survey via a general link outside Survalyzer, but still need to make sure that one person can submit the survey only once.
It is also recommended to use tpuid when collecting responses via URL exchange from third-party panel providers to ensure each participant completes the interview only once.
When the survey setting “allow multiple participation” is turned off, and survey is distributed using general survey link, participation is only tracked per device. So it is easy for participant to fill the survey again, when the same link is opened on another device, or in incognito browser mode.
tpuid parameter gives additional control, blocking users from participation across devices when using the link with unique tpuid value.
You normally do not need tpuid when respondents are invited from a Survalyzer sample using Survalyzer email invitations, or link-list distribution. In that case, Survalyzer already knows the respondent through its internal sample member ID, and duplicate participation is handled by the standard survey participation settings.
⚠️ Note: tpuid reduces duplicates but cannot guarantee 100% uniqueness. Read more.
How tpuid Prevents Duplicate Participation
When a respondent opens the survey, Survalyzer uses the tpuid value to identify their interview:
- If the tpuid value is new, Survalyzer creates a new interview.
- If the value belongs to an interview that is still in progress, the respondent returns to that interview and can continue where they left off.
- If the value belongs to a completed interview, the respondent cannot start another interview and sees the survey’s thank-you or already-filled page.
How the Unique Value is Passed in the Link
Your distribution tool (CRM, email platform, panel system) replaces a placeholder token with each respondent’s unique ID when generating the link.
Example:
?tpuid={{Contact.Id}} → respondent receives:
?tpuid=00Q5g00000AbCdE
You don’t need to fill in values manually, since this happens automatically at send time.
How to Set Up tpuid
- Copy the link to the survey from the Distribution tab of the Survey Builder.
- Add the tpuid parameter to the survey link:
https://[your-instance].survalyzer.eu/[survey-hash]?l=en&tpuid=[unique-value] - Set the external distribution system to automatically populate tpuid with its unique respondent ID when generating each respondent’s survey link.
- Launch the invitation send-out from the external distribution system.
Using tpuid with Other URL Variables
If you also use standard URL variables, tpuid can be added as an additional parameter. For example:
https://education.survalyzer.eu/lrguegvprz?l=en&urlVar01=[member-id]&tpuid=[unique-value]urlVar01 and tpuid can contain the same external respondent ID, but they have different purposes: urlVar01 is used as a regular URL variable, while tpuid is used by Survalyzer to block duplicate participation. For third‑party panel recruitment, we recommend using both parameters when setting up URL redirects.
Where tpuid is Available
tpuid is being introduced as a standard system URL variable. This means it’s available in the following places across Survalyzer:
Raw Data
Read more about raw data exports.
The tpuid value is read-only because it identifies a specific interview. It cannot be changed in the online raw data editor. If a raw data import contains tpuid values, Survalyzer ignores them. This mechanism protects personal data.
Rich Text Editor Placeholders
Read more about Rich Text Editor.
Question Filters
Read more about filters.
Table Filters
Read more about filter conditions in reports.
Dynamic Filters in Reports and Dashboards
Read more about report pages set up.
Workspace Anonymization Settings
tpuid is available in the workspace settings – anonymization. Since this value may identify a respondent in an external system, it should be treated as potentially personal data and selected for anonymization where applicable. When anonymized, tpuid values are hidden in raw data and other places where URL variables can be displayed or exported, such as placeholders, filters, reports, and dashboards.
Known Limitations
tpuid prevents repeated participation only as long as the unique parameter is present and unchanged in the survey URL. If a respondent removes the tpuid parameter from the URL or manually changes its value, they may be able to access and submit the survey again.
The duplicate-participation check using tpuid runs automatically in Survalyzer.
If needed, you can also export tpuid after fieldwork and use it for reconciliation or data‑quality checks with your external distribution system or panel provider.
Related Access Control Options
tpuid is one way to prevent duplicate participation, but it is not the only option. Depending on how you distribute your survey, you can also use the following Survalyzer features:
- Survey access settings: control whether respondents can open the same survey link more than once. See Access Control in Survey settings.
- Respondent-specific links: create unique links through Survalyzer email invitations, link-lists, or the API. See Public API – EU Datacenter.
- Third-party sample providers: use the provider’s quality controls together with the relevant Survalyzer access settings.
Tip: These options are not mutually exclusive. For the strongest protection against duplicate or fraudulent responses, combine selected approaches according to your needs.