When participants are sent from Prolific to your external survey tool, Prolific automatically adds three unique IDs to the link. These allow you to identify each participant and link their survey responses to their Prolific demographic data. The three IDs are:
Prolific PID — uniquely identifies a Prolific participant
Session ID — identifies the submission associated with that participant's connection to your survey tool
Study ID — identifies the Prolific study associated with the submission
If you're using the API, these IDs can also be used to authorize access in your external survey tool by calling the GET submission endpoint and validating the returned participant and study IDs.
Why do I need to record Prolific IDs?
Recording Prolific IDs allows you to link your survey responses to Prolific's demographic data. Without them, you won't be able to match a participant's survey answers to their Prolific profile, access their demographic information, or identify and reject poor-quality submissions.
How do I record Prolific IDs?
When setting up your study, you'll be asked how you want to record participant IDs. There are three options:
URL parameters (recommended)
Prolific automatically appends the three IDs to the link sent to participants. You'll need to configure your external survey tool to capture these. Each tool works differently — see our [integration guides] for step-by-step instructions for your preferred tool.
A question in your survey
You can ask participants to enter their Prolific ID directly in your survey, for example, "What is your Prolific participant ID?" You can then use this response to link survey answers to Prolific participants.
Note: this method relies on participants entering their ID correctly, and is vulnerable to both honest mistakes and deliberate misuse. Only use this approach if 100% accurate participant linking isn't essential for your study.
I don't need to record these
If you choose this option, you won't be able to link survey responses to Prolific participants, access their demographic data, or reject poor-quality submissions. This decision can't be reversed once your study is published. If you need to change it, you'll need to stop your study, duplicate it, update the setting, and publish the duplicate.
How do I secure my URL parameters?
If you want extra assurance that URL parameters haven't been tampered with between Prolific and your survey tool, you can enable "Secure external URL" when creating your study.
When enabled, Prolific securely signs all URL parameters before redirecting participants to your survey tool. The URL includes a JSON Web Token (JWT) containing these secured parameters. Your survey tool will need to verify the JWT before authorizing the participant to take the study.
This feature provides two key assurances:
Prolific IDs are accurate and protected from tampering
The token expires after 2 minutes, preventing participants from reusing the URL after their initial eligibility check
See our API integration docs for details on verifying the JWT, including the new property on the create-draft-study endpoint.
Note: This feature is only available to certain workspaces. However, if you’re interested, please register your interest here, and we'll be in touch once the feature is available in your workspace.
I didn't collect Prolific IDs. What can I do?
If you've completed your study and didn't collect Prolific IDs, we're unfortunately unable to provide them. Prolific doesn't store participant responses, so if the ID wasn't captured during the study, it can't be recovered.
If you ran your study on Qualtrics, you may be able to recover IDs by updating your survey settings and re-exporting your data. To attempt this:
Open your survey in Qualtrics
Go to "Survey flow"
Add or update an embedded data field named "PROLIFIC_PID"
Save your changes and re-export your data
IDs may appear after re-exporting, but this isn't guaranteed. If they don't populate after following these steps, they can't be recovered.