SIMPLE (Single-particle IMage Processing Linux Engine) is an open-source software suite for analysis of cryogenic electron microscopy (cryo-EM) single-particle data. It provides a complete processing pipeline from motion correction and CTF estimation to particle identification and 2D clustering, with a focus on real-time analysis and minimal CPU resource usage .

SIMPLE can be used on everything from high-performance clusters to everyday workstations and supports a flexible data processing workflow tailored to modern cryo-EM data rates.

SIMPLE was designed to address the growing computational demands of modern cryo-EM:

• Real-time processing — enable analysis as data is being collected, without waiting for post-acquisition batch workflows.
• CPU-efficient — optimized to perform well even on commodity hardware.
• Streamlined workflow — built-in pipelines automate key steps like motion correction, particle picking, and clustering.
• Flexible interface — a web-based GUI supports remote use and multi-user interaction.

This wiki is primarily intended for SIMPLE developers, outlining the software architectural principles deployed in SIMPLE, contribution conventions, and engineering practices for parallel code implementation using modern object-oriented Fortran and mixed-language programming with Fortran and C.