OpenJML vs Why3
OpenJML
openjml.orgWhy3
why3.orgSide by side
| Figure | OpenJML | Why3 |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | — | Yes |
| Windows | Yes | Yes |
| macOS | Yes | — |
| Linux | Yes | Yes |
| API | Yes | Yes |
| Self-hosted | — | Yes |
| Plans published | 1 | 1 |
| Spec score · Formal Verification Tools | 7.9 (#14) | 8.0 (#12) |
| License | The OpenJML User Guide states that the command-line tool is licensed under GPL version 2. | TryWhy3 is distributed under the GNU Lesser General Public License version 2.1 with a special linking exception. |
| Notable limitation | The feature status page says test suite generation is not yet supported because JMLUnitNG must be ported to Java 21. | Loop invariant inference is described as work in progress, with many features still very limited. |
| Purpose | OpenJML checks whether Java programs annotated with Java Modeling Language specifications satisfy those specifications. | Why3 is a platform for deductive program verification that uses WhyML and external theorem provers to discharge verification conditions. |
Plans
In their own words
Why3
Why3 is a platform for deductive program verification. It uses WhyML to express programs and specifications, then works with external automated or interactive theorem provers to discharge verification conditions. WhyML supports preconditions, postconditions, assertions, and loop invariants, alongside logical theories and data structures such as arrays, queues, and hash tables. External provers need to be installed and configured separately. Why3 can be extended with support for new provers and used as a software library through its OCaml API. WhyML programs can be extracted automatically into correct-by-construction OCaml programs, and WhyML is also used as an intermediate language for verification of C, Java, Rust, and Ada. TryWhy3 provides a JavaScript version that runs in a browser. Installation options include Opam, Docker, source compilation, and listed Debian, Fedora, and Ubuntu packages. Its graphical interface saves proof attempts and transformations in an XML file and can replay obsolete attempts. Why3 is free and open source under GNU LGPL 2.1 with a special linking exception. Loop invariant inference is a work in progress, and many features remain very limited.