Making open-source, vendor-neutral MRI more robust and accessible using Pypulseq - SUMMARY The open-source community has been a major driver of innovation of novel MRI image reconstruction and processing methods. The data acquisition step, on the other hand, has traditionally required proprietary, vendor- specific software tools that are complex and non-portable. We developed Pypulseq to enable the MRI research community to design and share vendor-neutral MRI pulse sequences using open-source tools. Pypulseq is built on the Pulseq file format, which has quickly established itself as the standard for specifying and sharing MRI pulse sequences. Pulseq also comprises a suite of vendor-specific interpreters, allowing the same Pulseq file to be executed across a variety of hardware platforms. Pypulseq is Python-based and can be installed freely in any computing environment without license requirements or accessed online through Google Colab. However, the rapid growth of Pypulseq and the Pulseq file format has produced a variety of disjoint tools that can be difficult to use, and that do not always guarantee correct operation across vendor platforms. The work proposed here addresses these needs through three specific aims. Aim 1 focuses on integrating and accelerating pre-scan safety checks related to SAR and PNS, and enabling users to input custom electromagnetic models. Aim 2 will make multi-vendor scanning with Pulseq more robust and efficient by refining the sequence specification and implementing a multi-vendor pulse sequence validator. Aim 3 will promote best practices for validating and robustly sharing Pulseq sequences, and disseminate Pypulseq advances through tutorials and workshops. This project will make Pypulseq sequences safer and more robust, in support of more reproducible MRI sequences and a faster MRI development cycle.