Jacksum is a free and platform independent software 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 58 popular standard algorithms (Adler32, BSD sum, Bzip2's CRC-32, POSIX cksum, CRC-8, CRC-16, CRC-24, CRC-32 (FCS-32), CRC-64, ELF-32, eMule/eDonkey, FCS-16, GOST R 34.11-94, HAS-160, HAVAL (3/4/5 passes, 128/160/192/224/256 bits), MD2, MD4, MD5, MPEG-2's CRC-32, RIPEMD-128, RIPEMD-160, RIPEMD-256, RIPEMD-320, SHA-0, SHA-1, SHA-224, SHA-256, SHA-384, SHA-512, Tiger-128, Tiger-160, Tiger, Tiger2, Tiger Tree Hash, Tiger2 Tree Hash, Unix System V sum, sum8, sum16, sum24, sum32, Whirlpool-0, Whirlpool-1, Whirlpool and xor8).

Jacksum supports the "Rocksoft (tm) Model CRC Algorithm", it can calculate customized CRC algorithms. With that feature you can apply additionally more than 1.0399*10^267 potential CRC algorithms using Jacksum.

Jacksum supports the combination of multiple algorithms.

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 OS X.

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 hashcode provided. With Jacksum you can calculate such a checksum or hashcode from your local copy. If both checksequences are identical you know that the filetransfer 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 a platform independent and compatible file format, 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 changed or deleted 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.


The Team

The long list of contributors can always be found in the latest download package and in the copyright section. The founder and lead for this project is Johann N. Löfflmann from Germany. Since 2002 he has been working with very talented people all around the world in order to improve Jacksum further.

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