Unique Turker



Unique Turker is a service that allows requesters on Amazon Mechanical Turk to limit the number of times that a single worker may work on a group of HITs. This service may be useful for:

  • Psychology or other scientific experiments, where unique workers are needed across a group of HITs.
  • Surveys or promotions, where you want to limit the number of HITs that a single worker may accept.
  • Any other task that could benefit from distinct workers.

Instructions (updated April 2020):

The preferred way to ensure unique workers is with Qualifications. Compared to other solutions, Qualifications create a better experience for workers and is more robust (harder for workers to circumvent).

Instructions are provided here: https://myleott.com/uniqueturker_via_quals.pdf

Old instructions (not recommended):

Use the form to the right to generate a custom script that you can copy and paste into the HTML of one or more of your HITs. The script will enforce a "Max # HITs / worker" constraint across all HITs where it appears.

Note: Be sure to use the same "unique identifier" across your multiple HITs. Scripts with different identifiers will use different databases.

Not sure where to paste the script? Try clicking "Edit HTML" in the "Design Layout" section of your HIT. Then, paste the script at the top of your HIT's HTML.

Limitations: Some workers are able to circumvent this script, so please double check submissions for duplicate Worker IDs.



Required: used to group your HITs (defaults to a random string)

Required: enter 1 for unique workers

Recommended: stay informed about changes, outages and updates to Unique Turker