Jacksum is a free and cross platform data integrity software tool for computing and verifying checksums, CRCs and message digests (known as hash values and fingerprints). "Jacksum" is a synthetic word made of JAva and ChecKSUM.

Jacksum supports 470 algorithms including national and international standards of cryptographic hash functions, candidates from round 2 and 3 from the NIST SHA-3 competition, and proposals from the 2005 NIST workshops before the SHA-3 competition, international accepted, modern strong cryptographic hash functions, eXtendable Output Functions (XOF) as cryptographic hash functions with a fixed length, and even broken cryptographic hash functions for education and backwards compatibility purposes, also checksums that can be found in software products and operating systems, and CRCs that are being used in many software products and protocols.

Jacksum takes advantage of modern muliti-processor/multi-cores environments for parallel computation and verification of hashes.

Jacksum supports the "Rocksoft (tm) Model CRC Algorithm", it can calculate customized CRCs.

Jacksum supports the combination of multiple algorithms.

With Jacksum you can also find the algorithm used to calculate a checksum/CRC/hash or find files that match a given hash value.

Both input and output are highly customizable, including charsets, encodings, formats, and compatibility files.

Jacksum has opened it's source code and it is released under the terms of the GNU GPL. Jacksum is OSI Certified Open Source Software. OSI Certified is a certification mark of the Open Source Initiative.  Jacksum is Free Software according the strong conditions of the Free Software Foundation.

Jacksum is cross platform, because it is written entirely in the Java programming language, the software runs on any platform having a Java Runtime Environment including GNU/Linux, Microsoft Windows and macOS.

Jacksum has multiple interfaces. It can be used on the command line, it can be integrated into your preferred file browser, and Jacksum's API can be called by your own project if using it as a library.

Use cases

With Jacksum you can check if a filetransfer was successful. If you download software or large files, like CD-, DVD-images, .iso-files  from the internet, often there is a checksum or a hash value provided. With Jacksum you can calculate such a checksum or hash from your local copy. If both check sequences are identical you know that the file transfer was successful.

Since Jacksum reads each byte of a file, you can check what files are still fully readable on your media.

Since Jacksum supports recursiv file processing, you can compare two directory trees. Therefore you will be able to verify, if your copies or backups are identical with the original source, even if you don't have access to both trees at the same time (compare two DVDs with just one drive for example).

Since Jacksum supports platform independent and compatible file formats, it helps you to verify data integrity of burned data on CD-ROMs or DVDs even after many years and even if you will have changed your Operating System.

Jacksum can support you by the unidirectional filesynchonisation, even if you don't have a connection between the two computers.

Jacksum can help you to create incremental backups.

If you are a developer, Jacksum can help you to create patches for your customers.

You can use Jacksum for intrusion detection, because Jacksum can check whether and what files have been modified, deleted or newly created on your system. Jacksum can not only check the content of each file you want, but also the timestamps of each file.

For more information please read the FAQ section.


Das Team

Die Liste von Mitwirkenden finden Sie stets im neuesten Download und in der Copyright Sektion. Der Gründer und Leiter dieses Projektes ist Johann N. Löfflmann aus Deutschland. Seit 2002 arbeitet er in seiner Freizeit mit talentierten Menschen aus aller Welt zusammen, um Jacksum gemeinsam weiter zu verbessern.

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