Prolific

Prolific puts three identifiers into the study link and gives you one completion URL for the whole study. Because that URL already contains everything Prolific needs, the redirect at the end of an Open Lab study is simpler here than for most providers.

Setup

Copy your study link (Open Lab)
Open the study, go to Invitations → Public links, and copy the Study link:
```
https://app.open-lab.online/studies/ABCDE
```
Set the study URL (Prolific)
Paste it into Prolific and append the identifiers you want to keep. Prolific offers three:
```
https://app.open-lab.online/studies/ABCDE?PROLIFIC_PID={{%PROLIFIC_PID%}}&STUDY_ID={{%STUDY_ID%}}&SESSION_ID={{%SESSION_ID%}}
```
The double-brace placeholders are Prolific's, and it replaces each one with that participant's real value. The names on the left of each = are yours; keeping them identical to Prolific's own names is the convention and makes the export easier to read later.
You are not obliged to pass all three. PROLIFIC_PID is the one worth having, because it is what lets you match an Open Lab participant to a Prolific submission.
Choose the redirect option (Prolific)
In the study's completion settings, take the completion URL Prolific gives you. It has this shape:
```
https://app.prolific.com/submissions/complete?cc=XXXXXXXX
```
The code after cc= belongs to the study, not to the participant, so this single URL is the same for everybody.
Add a Redirect component (Open Lab)
In the Study Builder, add a Redirect component as the last component, choose Paste a completion URL, paste that URL, and leave Redirect behavior on Stay in this tab.
Add no parameters. Unlike Sona or CloudResearch, Prolific is not expecting anything about the individual participant in the URL — the completion code alone tells it who to credit, because it already knows which submission is open. The Target URL is the entire configuration.

Copy the URL from your own study, every time

Prolific moved its domain from prolific.co to prolific.com, so any completion URL written down in an older tutorial — including on this page, which shows the shape rather than a working value — is a candidate for being stale. Take it from your study's completion settings.

If you use the completion-code method instead

Prolific also offers a method where you hand participants a completion code to copy and paste back. Prolific advises against it — a participant who closes the tab without copying leaves you nothing to identify them by — but if you use it, there is one thing to get right.

Do not use Open Lab's completion code for Prolific

Open Lab's Generate completion code feature invents a fresh code per participant. Prolific is waiting for its own study-level code and will not recognise anything else, so every submission would have to be reviewed by hand.

Show Prolific's code instead: copy it from Prolific and write it into the text of your Ending page. Leave the completion-code feature off.

The redirect method above is more reliable in any case — Prolific recommends it, and it removes the step where a participant closes the tab without copying anything.

Completion paths for different outcomes

Prolific lets a study carry several completion codes, each with its own automatic action — approve, reject, pay a bonus — for outcomes like an attention-check failure or a screen-out. Each still belongs to the study rather than to a participant.

Open Lab can only send everyone down one path

A study here ends in one Redirect component for all participants, and branching assigns conditions at random rather than on answers. So a second completion path cannot be chosen at run time: if you need one, the study has to end without a redirect and the paths have to be resolved on Prolific afterwards, by reviewing submissions.

Which names are yours and which are Prolific's

Name	Who decides it	Where it appears
`PROLIFIC_PID, STUDY_ID, SESSION_ID`	Yours to choose	Parameter names on your study link. Yours to choose; matching Prolific's own naming is the convention. These are what appear as columns on the Participants page.
`{{%PROLIFIC_PID%}}`	Fixed by the provider	Prolific's placeholder syntax, replaced when it builds each participant's link. Type it exactly, double braces included.
`cc`	Fixed by the provider	Already inside the completion URL you copied. One value for the whole study. Leave it alone.

Testing

Use Prolific's preview so the placeholders are filled in with real values; a plain Open Lab link cannot exercise the round trip. After the run, enable PROLIFIC_PID on the Participants page under Columns → Custom parameters and confirm it arrived, then check the submission in Prolific.

If submissions stay in Awaiting review when you expected them to complete automatically, the redirect is the place to look: confirm the Redirect component is the last component and that its Target URL matches the one in your study's completion settings.

How recruitment integrations work — the generic mechanism these steps are an instance of.
CloudResearch Connect — the same shape, with a per-participant ID to send back.