Prevent duplicate responses

Use Duplicate response prevention to reduce repeat submissions from the same respondent. This can help keep your results cleaner and more reliable.

Duplicate response prevention offers different ways to block another submission, depending on how you share your form and how you identify respondents.

Before you start

Duplicate response prevention is available on Growth Flow and Growth Custom plans.

The Unique URL parameter option is available on Growth Custom plans only.

How Duplicate response prevention works

Duplicate response prevention blocks another response only after a respondent has submitted a complete response.

If a respondent starts your form but doesn’t submit it, they can still come back and complete it later. This means you may see one or more partial responses as well as one complete response from the same respondent.

How to enable Duplicate response prevention

1. Open your form and click the Settings icon in the toolbar.

2. Under General, scroll down and toggle on Duplicate response prevention.

3. Choose how you want to prevent duplicate responses and set a response limit to control how many responses are allowed within a specific time period per respondent.

4. Click Save.

Below you’ll find a breakdown of each option.

Choose how to prevent duplicate responses

You can select one of the following options:

Cookies only

This option stores a cookie in the respondent’s browser after they submit a complete response.

If the same person tries to submit the form again in the same browser, they’ll be blocked.

Use this option when you want a lightweight way to reduce repeat submissions.

Keep in mind that respondents may still be able to submit again if they:

• clear their cookies
• switch to another browser
• use another device

Cookies and IP address

This option uses both a browser cookie and the respondent’s IP address to reduce repeat submissions.

If the same person tries to submit the form again from the same browser and network, they’ll be blocked.

Use this option when you want stronger protection than cookies alone.

Keep in mind that:

• respondents may still be able to submit again if they clear their cookies, switch browsers, or change networks
• different respondents who share the same IP address may also be blocked

Unique URL parameter

This option requires a non-empty, unique value in a selected URL parameter before a respondent can start your form.

Use this option when you already identify respondents through a shared link, app, CRM, or email workflow.

For example, you might pass a value like a customer ID, user ID, or device ID in the form URL.

If a complete response has already been submitted with that same value, the next person who opens the form with the same value will be blocked before they start the form.

Before you use this option

Before you can use this option, your form must already have at least one enabled URL parameter.

To add URL parameters to your form:

1. Open your form and click Workflow.

2. Click the + sign under Pull data in to add or enable the URL parameter you want to use.

3. You can add a custom URL parameter or choose from the list of predefined parameters.

4. Click Save.

5. Publish your form so the parameter is added to your share link.

Set up Unique URL parameter prevention

1. Open your form and click the Settings icon in the toolbar.

2. Under General, toggle on Duplicate response prevention and select Unique URL parameter.

3. From the dropdown, choose the URL parameter you want to use.

4. Set a response limit to control how many responses are allowed within a specific time period per respondent.

5. Click Save.

Example

If your form uses a URL parameter called device_id, your form link might look like this:

https://form.typeform.com/to/ABC123?device_id=abcde

If someone completes the form using that link, another attempt with device_id=abcde will be blocked.

If someone opens the form with a different value, such as device_id=abcdef, they can start the form normally.

What respondents will see

When a respondent is blocked by Duplicate response prevention, they’ll see a message letting them know they’ve already submitted a response. It isn’t currently possible to customize this message.

FAQ

What happens if a respondent submits a partial response?

They can still return and submit a complete response later. The block starts only after the first complete response is submitted.

What happens if the URL parameter is missing or blank?

With the Unique URL parameter option, the respondent won’t be able to start the form if the URL parameter is missing or blank. A unique value is required.

Does capitalization matter in URL parameter values?

No. Matching is case-insensitive.

For example, if one response was submitted with device_id=123ABC, another attempt with device_id=123abc will still be blocked.

What happens if the URL parameter value is longer than 100 characters?

If the selected URL parameter value is longer than 100 characters, this duplicate prevention rule won’t be applied.

In that case, the respondent won’t be blocked by the Unique URL parameter option.

When are duplicate responses still possible?

Depending on the option you choose, respondents may still be able to submit more than once if they clear cookies, switch browsers, use another device, or change networks.

If you use the Unique URL parameter option, duplicate prevention depends on the value passed in the form URL being present and unique.