PrimeGrid is a volunteer computing project that searches for very large (up to world-record size) prime numbers whilst also aiming to solve long-standing mathematical conjectures.

Different subprojects may run on different operating systems, and may have executables for CPUs, GPUs, or both; while running the Lucas–Lehmer–Riesel test, CPUs with Advanced Vector Extensions and Fused Multiply-Add instruction sets will yield the fastest results for non-GPU accelerated workloads.

PrimeGrid awards badges to users in recognition of achieving certain defined levels of credit for work done.

PrimeGrid started in June 2005[1] under the name Message@home and tried to decipher text fragments hashed with MD5.

Message@home was a test to port the BOINC scheduler to Perl to obtain greater portability.

With the chance to succeed too small, it discarded the RSA challenges, was renamed to PrimeGrid, and started generating a list of the first prime numbers.

In June 2006, dialog started with Riesel Sieve to bring their project to the BOINC community.

In the fall of the same year, PrimeGrid migrated its systems from PerlBOINC to standard BOINC software.

[46] PrimeGrid has also been featured in an article by Francois Grey in the CERN Courier and a talk about citizen cyberscience in TEDx Warwick conference.

[47][48] In the first Citizen Cyberscience Summit, Rytis Slatkevičius gave a talk as a founder of PrimeGrid, named Finding primes: from digits to digital technology,[49] relating mathematics and volunteering and featuring the history of the project.