Published July 6, 2017 | Version v1
Poster Open

CWL Viewer: The Common Workflow Language Viewer

  • 1. School of Computer Science, The University of Manchester, UK
  • 2. Common Workflow Language project


The Common Workflow Language (CWL) project emerged from the BOSC 2014 Codefest as a grassroots, multi-vendor working group to tackle the portability of data analysis workflows. It’s specification for describing workflows and command line tools aims to make them portable and scalable across a variety of computing platforms. 

At its heart CWL is a set of structured text files (YAML) with various extensibility points to the format. However, the CWL syntax and multi-file collections are not conducive to workflow browsing, exchange and understanding: for this we need a visualization suite.

CWL Viewer is a richly featured CWL visualization suite that graphically presents and lists the details of CWL workflows with their inputs, outputs and steps. It also packages the CWL files into a downloadable Research Object Bundle including attribution, versioning and dependency metadata in the manifest, allowing it to be easily shared. The tool operates over any workflow held in a GitHub repository. Other features include: path visualization from parents and children nodes; nested workflows support; workflow graph download in a range of image formats; a gallery of previously submitted workflows; and support for private git repositories and public GitHub including live updates over versioned workflows. 

The CWL Viewer is the de facto standard CWL visualization suite and has been enthusiastically received by the CWL community.

  • Project Website:
  • Source Code:
  • Software License: Apache License, Version 2.0
  • Submitted abstract: CWL Viewer: The Common Workflow Language Viewer
  • Technical Report: Reproducible Research using Research Objects


CWL Viewer is live at Abstract peer-reviewed and accepted for poster+talk at BOSC 2017.



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Additional details


BioExcel – Centre of Excellence for Biomolecular Research 675728
European Commission