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This repository hosts VerCors, a toolset for the verification of concurrent and parallel programs. VerCors aims to verify many different concurrency constructs, including: heterogeneous concurrency (Java and C), GPU kernels using barriers and atomics (OpenCL), and compiler directives as used in deterministic parallelism (OpenMP). VerCors is able to prove data-race freedom, memory safety, and functional correctness of (concurrent) programs written in Java, C, OpenCL, OpenMP, and PVL (Prototypal Verification Language, a procedural toy language for prototyping new verification features). Moreover, VerCors is designed to be language-independent, which makes adding new front-end languages a straightforward engineering effort.

A list of verified examples and case studies is maintained online and can be found here. This webpage also contains an online interface for VerCors and allows you to try VerCors online.

The tutorial can be found on the VerCors Wiki!


You can install VerCors by either using a release (recommended for beginners), or by building VerCors from its source code.

Using a Release

VerCors requires a java runtime environment (version 17 or later), as well as clang if you want support for C.

Debian Linux

Currently we support debian-based systems; let us know if you need something else! Install the dependencies:

sudo apt install clang openjdk-17-jre

Obtain the latest deb release of VerCors here, and install it by running:

sudo dpkg -i Vercors_x.y.z_all.deb

VerCors should now be on the path:

$ vercors /usr/share/vercors/examples/concepts/arrays/array.pvl
[INFO] Starting verification
[INFO] Verification completed successfully.


You can for example obtain the dependencies through homebrew:

brew install java

This should install the latest release of OpenJDK. Clang should already be installed through XCode.

Obtain the latest tgz release of VerCors here and unpack it. You can find the run script for VerCors in the bin subdirectory:

$ ./bin/vercors examples/concepts/arrays/array.pvl
[INFO] Starting verification
[INFO] Verification completed successfully.

NB: you may need to allow the dependencies of VerCors to run manually. If you get an error that z3 and/or boogie is not from a trusted developer, execute them once manually from Finder to add an exception (instructions). They are located at:

  • res/deps/z3/4.8.6/Darwin/x86_64/bin/z3
  • res/deps/boogie/


You can obtain a java runtime environment e.g. here. Make sure that the environment variable JAVA_HOME points to wherever you unpack the JDK. clang can be obtained as part of the llvm toolchain here. Make sure that clang is added to the path.

Next, download the latest zip release of VerCors here and unzip it. You can find the batch script for VerCors in the bin subdirectory:

> bin\vercors.bat examples\concepts\arrays\array.pvl
[INFO] Starting verification
[INFO] Verification completed successfully.

Building from source code

When building VerCors, you additionally need these dependencies:

  • A Java Development Kit, version 17 or greater, either OpenJDK or Oracle.
  • Git (on Windows you need Git Bash, see
  • Optionally cmake, make and libllvm15-dev if you would like to build VCLLVM (this is currently restricted to linux)
  1. Clone the VerCors repository using git clone and move into the cloned directory, cd vercors.
  2. Run ./mill vercors.main.compile to compile VerCors.
  3. Test whether the build was successful by running ./bin/vct examples/concepts/basic/induction-lemma.pvl.
  4. (optional) Enable building VCLLVM with touch .include-vcllvm

Running VerCors

VerCors verifies programs that are annotated with JML-style specifications (the underlying theory uses separation logic with permission accounting). Details on the specification language can be found on the VerCors Wiki pages. Furthermore, a large collection of example programs can be found (and verified) in the ./examples directory.

The VerCors toolset can be used by running vercors <filepath>, with <filepath> the path of the (Java, C, or PVL) file to verify.


Related papers

A complete list of papers on the VerCors project is given here.


Copyright (c) 2008 - 2023 Formal Methods and Tools, University of Twente All rights reserved.

The license to VerCors is a mozilla open source license as described in LICENSE.TXT in the root of this project. It is a free to use, share-alike license. Should this license be too restrictive for your purpose, please let us know by creating an issue in our bug tracker. Direct contributors (people who send us pull-requests or edit this repository directly) are expected to agree with any license that the University of Twente might decide. If you do not agree with future license changes, please instead fork this repository as allowed under the conditions of LICENSE.TXT.