SDFormatter : software to format SD/SDHC/SDXC
Minitool Partition wizard free : software for formatting in different formats
WIN32 Disk Imager : allows you to create an image of your microSD
Balena Etcher : cross-platform tool to flash an .img file on storage devices (micro-SD card/hard disk)
7zip : perfect to unzip your romset in 7zip.001 7zip.002 format.
BestArcade4Recalbox list (document deleted since) lists the compatibility of arcade romsets for recalboxOS
Skraper : Skraper is a tool allowing you to scrape your roms directories. It is based on screenscraper.fr and is available for Windows and Linux.
Universal XML Scraper : Universal XML Scraper allows you to scrape your roms directories simply based on the screenscraper.fr site which is a FR (but also worldwide) (local) database.
Universal XML Editor - Simply edit your xml files (local)
Universal ROM Cleaner - Clean your romset in one click (local)
For SegaCD, PCengineCD and PSX
Monkey Audio : allows you to unzip ape files into wav files.
emctools : allows to unzip the bin.ec format
psx2psp : allows you to merge several CDs
SegaCD Cue Maker : allows you to create missing cues for your bin Sega CD files only.
N64 Rom Renamer by Einstein II: To rename the internal name of the rom.