PRSM is a free app for drawing and understanding systems collaboratively

The Participatory System Mapper (PRSM) is an app that makes it easy to draw networks (or 'maps') of systems

It runs in a web browser on a desktop PC or a tablet.

When you start PRSM in your browser, a 'room' is created for you in which to draw your network. You can add other users to this room to share the work. Only those with access to the room can see what is being created.

What can you map?

The network or map can be anything that has items (or 'factors' or 'nodes') connected by links (or ‘edges').

  • People (the nodes) connected by knowing each other
  • Factors or variables causing (the links) changes in other factors
  • Switches connected by wires
  • Computers connected by network links
  • Theories expressed as variables and relationships between them
  • Company boards of directors (the nodes) and the directors that sit on more than one board (the links)
  • Twitter hashtags (the nodes) included together on posts (the links)
  • Scientists (the nodes) co-authoring papers (the links)
  • … and anything else that has items and links between the items

Groups of people, each using their own computer (or tablet) can collaborate in the drawing of a map using PRSM

They may be sitting around a table, discussing the map as it is created face to face, or working remotely, using video conferencing or the chat feature that is built into the app.

Everyone can participate because every edit (creating nodes and links, arranging them, annotating them, and so on) is broadcast to all the other participants as the changes are made.

To use PRSM, all you need is a modern web browser such as Chrome, Firefox, Microsoft Edge or Safari running on a desktop, tablet or phone.

It will not work with Internet Explorer.

The software is free, open source and available under an MIT license.

PRSM is secure — the only way to gain access to a map is if you have the web address of the shared ‘room’, a random string of 12 letters.

Encoded data is transmitted between users using a server located in Ireland, and so does not leave the jurisdiction of the GDPR. You can save maps to your local computer in PRSM’s own format, save an image of the network, or export maps in one of several standard network formats.

PRSM is GDPR compliant: for details see our privacy notice.


The Centre for the Evaluation of Complexity Across the Nexus (CECAN) was founded in 2016 as an ESRC research centre, with the aim of 'transforming the practice of policy evaluation across the food, energy, water and environmental domains to make it fit for a complex world'. Since then, CECAN has worked closely with UK government departments and others and has developed a methodology for creating participatory system maps. These maps were thought to be very helpful to those who worked on them — policymakers, policy analysts, and stakeholders in public policy — but it was laborious digitising the paper and Post-It™ notes that were used in mapping sessions. We therefore began investigating the possibility of asking participants to use mapping software.

Shortly afterwards (early 2020), the COVID-19 pandemic meant that the kind of face-to-face mapping workshops we had been organising were no longer feasible. Over the course of 2020, we developed PRSM and somewhat hesitantly tried it out with some pilot workshops. Gradually, the reliability and capability of PRSM improved, and we learned how to run system mapping workshops online, which requires somewhat different strategies than face-face workshops. The core of PRSM is now stable and well tested, but it continues to be extended to add further features.

CRESS and ESRC logos

PRSM has been developed by the
Centre for Research in Social Simulation and the
Centre for the Evaluation of Complexity Across the Nexus (CECAN)
at the University of Surrey, UK
2019 – 2021
with support from the
Economic and Social Research Council
and the University of Surrey

PRSM was designed and written by Nigel Gilbert.

CECAN and Surrey logos

With thanks to all who helped inspire, suggest features for and test PRSM, including Paul Brand, Brian Castellani, Robin Gilbert, Kevin Jahns, Robert MacKay, Kavin Narasimhan, Alex Penn, Bazil Sansom, Helen Wilkinson, and many others.