Jacksum

Jacksum is a fast, multi-threaded command-line tool and Java library for calculating and verifying cryptographic hashes, checksums, and CRCs — 586 algorithms, one consistent interface. Whether you verify file integrity, automate security checks, hunt down duplicates, or work with rare and exotic algorithms — Jacksum makes hashing effortless on Windows, macOS, Linux, and even Android.

Prefer a visual workflow? Meet HashGarten, the official graphical interface for Jacksum.

Cross-Platform

Jacksum runs on Microsoft Windows, macOS, and GNU/Linux — and even on Android. Written entirely in Java, it needs no recompilation and behaves identically everywhere: same command, same output, on every platform.

Use cases

Anywhere hash values make sense, Jacksum has you covered.

Calculate

  • Hashes and fingerprints of almost any input: files, entire file trees, command line args, plain or encoded strings, the console, standard input, NTFS ADS, pipes, sockets, doors, partitions, and raw disks
  • Pseudo random numbers, and reproducible, unique, secure passwords

Verify

  • Generate and persist check lists and wanted lists
  • Verify data integrity — find files that are OK, failed, missing, or new
  • Run a strict integrity verification, aka an audit

Find

  • Find files by their fingerprints (positive matching)
  • Find files that don't match certain fingerprints (negative matching)
  • Find every duplicate of a file by its hash value
  • Find the algorithm(s) that produced an unknown hash value

Investigate

  • Get detailed algorithm information — including whether an algorithm is considered broken
  • Examine the polynomials of CRCs and the parameters of HMACs

For complete, copy-and-paste recipes, see the Use Cases cookbook.

Key facts

  • 586 algorithms — cryptographic hash functions, CRCs, and classic checksums
  • HMAC support for 490+ hash functions
  • Customizable CRCs from 1 to 64 bit width
  • 70 command line options to control Jacksum's behavior
  • Cross-platform — identical behavior on every supported system
  • Multi-threading — parallel hash calculations and parallel data reads, to get the most out of
    multi-core CPUs and fast SSDs
  • Recursive traversal with depth control, symbolic link policies for files and folders, and file
    system cycle detection
  • 18 predefined stylesstrong> for reading and writing check files, 15 of them for wanted lists
  • 17 encodings for representing hash values
  • 6 predefined stylesstrong> for file timestamps
  • 170+ character sets, so hash files are read and written correctly
  • Fully customizable output format
  • 10,000+ lines of documentation with descriptions, examples, and compatibility lists for every
    supported algorithm

For the full picture, see the comprehensive list of features.

Audience

Jacksum is built for people who take integrity seriously: sysadmins, cybersecurity and forensics engineers, penetration testers and white hat hackers, reverse engineers, CRC researchers, computer science students, and advanced users in general.

It's a professional tool — but thanks to HashGarten, which bundles the Jacksum library, it's just as available to users who never open a terminal.

System requirements

  • GNU/Linux, Microsoft Windows, or macOS
  • A JRE/JDK compatible with Java 21 LTS or later (OpenJDK 25 LTS or later recommended)
  • 2 MiB of disk space

See Install for supported architectures and further details.

Algorithm support

Jacksum supports algorithms out of the box: cryptographic and non-cryptographic hash functions, CRCs, and classic checksums. It supports HMAC, the mechanism for message authentication that combines any iterated cryptographic hash function with a shared secret key.

It also implements the Rocksoft™ Model CRC Algorithm, so on top of the built-in ones you can define roughly 10²⁶⁷ custom CRCs of your own.

See Algorithms for the full list, and the Algorithm Selection Guide to decide which one fits your use case.

Interfaces

Jacksum comes with a command line interface and a programming interface. A graphical interface is provided by HashGarten, and both can be wired into your file browser.

Command Line Interface (CLI)

The full power of Jacksum, ready to be scripted. Call it from shell scripts, cronjobs, CI pipelines, or AI agents to automate integrity and verification tasks. See the manual.

Graphical User Interface (GUI)

If you just want to calculate and verify hashes by pointing and clicking, get the File Browser Integration installer, which ships with HashGarten, the
official GUI for Jacksum. HashGarten also runs standalone and supports drag and drop.

File Browser Integration (FBI)

The FBI installer integrates Jacksum and HashGarten directly into your file browser — Finder on macOS, File Explorer on Windows, and Caja, Dolphin, elementary Files, GNOME Nautilus, Konqueror, Krusader, muCommander, Nemo, ROX-Filer, SpaceFM, Thunar, Xfe, or zzzFM on GNU/Linux. Head to
Downloads.

Application Programming Interface (API)

Jacksum is a library, too — feel free to use it in your own project.

License

Jacksum is free and open source software, released under the GPL-3.0 or later. It is OSI Certified Open Source Software — OSI Certified is a certification mark of the Open Source Initiative — and Free Software in the strong sense defined by the Free Software Foundation.