Crystal Databases & CIF Download

COD (Crystallography Open Database) ICSD (Inorganic Crystal Structure Database) Materials Project
AMCSD (American Mineralogist Crystal Structure Database)
Springer Materials
IUCr Journals Database
AFLOW Library

XRD Simulation Tools

VESTA
PowderCell
Mercury (CCDC)
CrystalMaker

Rietveld Refinement

FullProf Suite
GSAS-II
TOPAS
MAUD

Synchrotron Facilities

ESRF (European Synchrotron Radiation Facility)
APS (Advanced Photon Source)
Diamond Light Source
SPring-8

Industrial XRD Companies

Bruker
Rigaku
Malvern Panalytical
Thermo Fisher Scientific

Open Source Tools

GSAS-II
FullProf Suite
VESTA
PDFgui

Crystallography Servers

Bilbao Crystallographic Server
IUCr (International Union of Crystallography)
OQMD Database

Learning Resources

IUCr Online Teaching & Tutorials
MIT OpenCourseWare (MIT OCW)
NPTEL
Bruker Academy