PSA DiagBox 9.87 is a professional-grade diagnostic software used for Peugeot, Citroën, DS, and newer Opel vehicles (up to 2020)
No, for casual owners: If you own just one Peugeot or Citroën, consider a handheld scanner (like Topdon or Autel) instead. The learning curve of Diagbox is steep; one wrong "Telecoding" click can brick your BSI, requiring a dealer visit. PSA Diagbox 9.87 -x86-x64- Multilingual.zip
Conclusion
The software provides dealership-level access to various Electronic Control Units (ECUs): Diagbox for Citroen (and how to get swindled) PSA DiagBox 9