---
url: "https://questionstar.com/help/survey-settings/recognizing-returning-respondents/"
title: "Recognizing returning respondents — preventing multiple submissions"
description: "Reliably detect and block multiple submissions: via cookies, IP, email tokens, or unique identifiers. An overview of the methods."
lastmod: "2026-07-08"
type: "help"
---

# Recognizing returning respondents

## Why does recognition matter?

For the **“Allow pausing and resuming survey completion”** and **“Prevent multiple submissions”** features to work reliably, QUESTIONSTAR needs to be able to recognize returning respondents. Two mechanisms are used for this:

- **Personalized links**
- **Cookies**

## 1. Personalized links

When personalized links are used, a **pseudonymized identification number (ID)** is embedded directly into the survey link. Using this ID, QUESTIONSTAR can identify each respondent unambiguously — regardless of the device or browser used.

When such a link is reopened, the completion session is reliably recognized. Respondents can therefore resume their survey seamlessly or be prevented from completing it more than once.

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> **Important:**
> Because the ID is contained directly in the link, **the link must not be forwarded to other people**. Otherwise, the recipient would not start their own new completion session, but would continue the session already begun by the sender.

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> The personalized links are generated in the **“Personal Links”** section of the **“Distribute Survey”** view. If you use the built-in mailer for the invitation, the links are created automatically and inserted into the emails (see the *“Distributing surveys”* section).

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> The identification parameters in the links are **randomly generated**, so that they allow no conclusions to be drawn about personal data. With the **“Anonymize IDs”** setting enabled, any link between a respondent and their answers is technically ruled out.

## 2. Cookies

When participation happens via a **public survey link**, no individual ID can be passed along. In this case, the first time the survey is opened, QUESTIONSTAR stores **a cookie in the respondent’s browser** — that is, a small text file with a randomly generated, unique identifier.

This identifier is anonymous, as it contains no personal information whatsoever.

When the questionnaire is opened again, QUESTIONSTAR checks whether the cookie is still present:

- **Cookie present:** Provided the “Allow pausing and resuming survey completion” setting is enabled, the completion session that was started is restored automatically.
- **Cookie not present:** The session cannot be recognized, and the questionnaire starts over — that is, a new session begins.

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> **Note:**
> Recognition via cookie works **only in the same browser on the same device** on which the original session was started. If the browser cache is cleared, a different browser is used, or a private browsing session is used, the cookie cannot be read — and the session is not resumed.

## Which method makes sense when?

- **Personalized links** are especially suited to **non-anonymous surveys** where it’s important to identify respondents unambiguously — for example, for personalized invitations, follow-up, or targeted reminders. They provide a high level of reliability in recognition, regardless of device or browser.
- **Cookies** are the right choice for **anonymous surveys with public access** where no personal data is to be processed. They allow recognition as long as the cookie is present — but only on the same device and in the same browser.

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> Unless the survey was opened via a personalized link, QUESTIONSTAR automatically switches to cookie-based recognition mode.