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Study Randomizer

Simple, easy randomization for research studies and clinical trials.

Used in leading research organizations
University of Oxford (UK), Yale University (US), The University of Sydney (AU), KU Leuven (BE), University of Oslo (NO), University of Florida (US), Southern Medical University (CN), Uppsala University (SE), Dalhousie University (CA), University of Westminster (UK), Ruhr University Bochum (DE), NHS Foundations (UK), Medicor Research Inc (CA), Northern State Medical University (RU), University of Utrecht (NL), Temple University (US), ...

Automate your trial randomization Automate your trial randomization

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Study Randomizer Features

Easy to use

Access study data and enroll participants from any web browser. No more paper envelopes or slow phone systems.

Set up multiple organizations and trials

You can set up multiple trials. Each trial is independent from other trials. Set up separate organizations administering separate trial groups.

How to use Study Randomizer
Study Randomizer dashboard
Select randomization options

Powerful randomization options

Use comprehensive randomization algorithms (permuted blocks, minimization, adaptive randomization, stratification, and more). Delegate study enrollment to multiple users.

Design and simulate your trial

Design your trial in the interactive design form. Test different parameters and trial designs. Simulate trial randomization. Use stratification on variables for multi-center and multi-site studies.

Study Randomization Information


Use live enrollment or pre-enrollment with coding for double-blind studies. You can use Study Randomizer in multiple locations with internet access.

Invite collaborators

Invite collaborators into the system. Use multi-user access controls to allow view, enroll, or edit privileges.


Data is encrypted, backed up, and protected. Transactions are logged and an auditable record can be provided.

Security Information


Free for small studies, significantly cheaper than an expensive CTMS or EDC system for large studies.



Integrate with HIPAA and GDPR requirements for data security and data residency. Study Randomizer does not store trial subject information and can work with your patient record system, whether it's on paper or digital.


Full configuration of study arms & variables (text, number, group type). Choose between urn and block based randomization. Set up multi-site studies by stratifying using a variable for the trial site.

Register and design your trial

How Study Randomizer works

The Problem

You need to set up a trial with randomization. Simple usage is important.

Sign Up

Create an account at Study Randomizer and confirm your email.

Design and Simulate Your Trial

Make sure your trial design works. Simulate block allocation and trial imbalance. Test stratification for e.g. multi-center trials.

Invite collaborators

Make sure multiple people can enroll trial subjects. Give view-only access to administrative staff.

Start Trial Enrollment

Enroll trial subjects with the click of a button wherever you have access to internet.

Enrollment Records

You can print enrollment records for archiving or offline usage.

Study Randomizer Use Cases

Study Randomizer is used worldwide in trials. Partial list of studies where Study Randomizer is used: Study Randomizer Studies

Randomization software has many use cases such as:

Clinical Trials: Study Randomizer is used in many clinical trials world-wide. From helping with Covid-19 trial randomization to improve clinical outcomes for patients to supporting sleep studies to psychosis research.

Veterinary trials: Dose requirements for anesthesia in dogs.

Psychological trials: Simple randomization support for trial enrollment.

Food trials and research: Bioavailability and food ingredient influence on serum levels in the human body.

Economic research: Effects of mentoring on smaller companies.

Get started and design your trial

How to do Clinical Trial Randomization

Randomization is a key aspect of clinical trials that helps to ensure that the results of the study are the result of the treatment and unbiased. To perform randomization in a clinical trial, you first need to determine the number of participants in the study and the number of different groups (or "arms") that the participants will be assigned to. Then, you need to create a randomization schedule that specifies which participants will be assigned to which group. This can be done using a computer program like or by using randomization cards or tables. Once the randomization schedule has been created, the participants can be enrolled in the study and assigned to their respective groups according to the schedule. It is important to keep the randomization schedule confidential to avoid biasing the results of the study.


Get in touch. We’re happy to talk about your project’s specific needs.
Contact us for additional requirements for Study Randomizer.

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Study Randomizer is made by:
Phase Locked Software
The Netherlands

Photo by Frédéric Paulussen on Unsplash