Side by side

ACL2 vs CPAchecker

Both stand on formal verification tools. Which one you can start free with, which one lets you read the code, and what each costs once you pay.

ACL2

Free plan LinuxMacSelf-hosted+1

ACL2 combines a theorem prover with libraries and documentation for formal verification across several operating systems. Check the Lisp prerequisite and version note before installing.

Visit ACL2

CPAchecker provides a focused set of configurable program-verification capabilities, with multiple installation routes and supporting documentation. Check that your input language, Java version, and deployment environment match its requirements.

Visit CPAchecker

The facts

	ACL2	CPAchecker
Free plan	Yes	Yes
Open source	Not published	Not published
Runs on	Linux, Mac, Self-hosted, Windows	Linux, Mac, Self-hosted, Windows
Lowest paid plan	Not published	Free or on request
Plans published	None	1
Maker	Not published	Not published
Website	acl2.org	cpachecker.sosy-lab.org
On formal verification tools	#7 of 34	#3 of 34

ACL2: what it does well

Free and self-hosted.
Runs on Linux, macOS, FreeBSD, and Windows.
Community Books include proof and hardware-verification libraries.
Documentation is available in several formats.
Supports counterexamples and proof artifacts.

What to know first

Requires a Common Lisp implementation.
Some books are guaranteed only with CCL or SBCL.
Version 8.7 lacks fixes and improvements since March 2026.
Building all Community Books can take hours.

CPAchecker: what it does well

Free software under the Apache 2.0 License
Supports C and SV-LIB inputs
Produces counterexamples and proof artifacts
Offers Debian and Ubuntu installation through APT
Docker image is available

What to know first

Requires Java 21 or later
Older web version lacks some features
Newer Linux configurations may require recent distributions

Alternatives to ACL2 Alternatives to CPAchecker The whole list