For Massacre Mission Locations - https://edtools.cc/pve
You need to enter the system you're in (Reference System) and the search radius (30-100 ly).
The resulting data is a list of "source" systems within the radius, and is presented as a table, with the following columns:

• Distance: distance from the Reference system to a source system
• System: name of a source system. Can be copied to clipboard by clicking the icon to the left of it. Links to source system's page on eddb
• L-pad: distance to the closest station with a large landing pad, if any
• M-pad: distance to the closest outpost with a medium landing pad, if any
• P-pad: distance to the closest planetary port, if any
• Fed: number of Federation-aligned minor factions in source system
• Imp: number of Empire-aligned minor factions in source system
• All: number of Alliance-aligned minor factions in source system
• Ind: number of Independent minor factions in source system
• Target/Sources: name of the target system, to which "massacre pirates" missions will be given by minor factions in "source" system. Can be copied to clipboard by clicking the icon to the left of it. Links to target system's page on eddb. If more than one "source" system gives missions exclusively to that system, there will be a number of those. You can further research the target system by clicking on that number.
• RES/Rings: If there's information in RES finding tool for target system, then it's a list of RES types presented in it, otherwise the number of ringed planets in the target system, if known. Those rings might have RES, or they might not.