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Tech riderRev. 20 Sept 2026

Dafny

Ch 166.2of 33 Formal Verification Tools
  1. 1Runs onLinux, Mac, self-hosted, Windows
  2. 2CostsNot stated by the maker
  3. 3Verification methoddeductive
  4. 4Supported formalismscontracts
  5. 5CounterexamplesYes
  6. 6Input languagesDafny
  7. 7Deploymentself-hosted
6 lines stated Written from the maker's own pages: dafny.org
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Overview

Dafny is ranked #16 of 33 in formal verification tools on Specifiction. It runs on Linux, macOS, Self-hosted, Windows.

Compared on formal verification tools

Free plan
Yesdafny.org
Verification method
deductivedafny.org
Supported formalisms
contractsdafny.org
Counterexamples
Yesdafny.org
Input languages
Dafnydafny.org
Deployment
self-hosteddafny.org

Facts

Product
Dafny is a verification-aware programming language with native specification support and a static program verifier.dafny.org · 5 Oct 2026
Purpose
It helps developers write code that can be verified against specifications to reduce the risk of late-stage bugs.dafny.org · 5 Oct 2026
Compilation targets
Dafny can compile programs to C#, Java, JavaScript, Go, and Python.dafny.org · 5 Oct 2026
Proof features
Its proof toolbox includes quantifiers, calculational proofs, lemmas, preconditions, postconditions, termination conditions, loop invariants, and read/write specifications.dafny.org · 5 Oct 2026
Language features
The language supports classes, iterators, arrays, tuples, generic and subset types, inductive datatypes, lambdas, and mutable and immutable data structures.dafny.org · 5 Oct 2026
IDE integrations
The Dafny ecosystem includes a Visual Studio Code extension powered by a Language Server Protocol implementation, plus a code formatter.dafny.org · 5 Oct 2026
VS Code features
The VS Code extension supports verification while typing, compiling and running .dfy files, syntax highlighting, verification traces, IntelliSense, go to definition, and hover information.marketplace.visualstudio.com · 5 Oct 2026
Platforms
Installation instructions cover Windows, Linux, and macOS; the project repository also lists binary downloads for FreeBSD.dafny.org · 5 Oct 2026
Requirements
The Dafny tool is a .NET 8.0 artifact, and Dafny plus its bundled Z3 tool are sufficient for verification; compiling and running generated programs may require additional tools.dafny.org · 5 Oct 2026
Security reporting
The project asks people who discover a potential security issue to notify its security contact instead of creating a public GitHub issue.github.com · 5 Oct 2026
License
The Dafny software is licensed under the MIT License.github.com · 5 Oct 2026
Support
The project directs users to its Zulip channel for questions and GitHub for issue reports.github.com · 5 Oct 2026
Audience
Dafny is used in academia for teaching and research and in industry, including by teams at Amazon.dafny.org · 5 Oct 2026

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