Here is a list of all modules:
 ActionsA collection of steps used in algorithms
 Analytic DataAnalytic data used to specify (for example) initial data to the equations implemented in Evolution Systems
 Analytic SolutionsAnalytic solutions to the equations implemented in Evolution Systems and Elliptic Systems
 Boundary ConditionsA collection of boundary conditions used for evolutions
 Charm++ ExtensionsClasses and functions used to make Charm++ easier and safer to use
 Computational DomainThe building blocks used to describe the computational domain
 Conservative System EvolutionContains generic functions used for evolving conservative systems
 Constant ExpressionsContains an assortment of constexpr functions
 Control SystemContains control system elements
 Coordinate MapsFunctions for mapping coordinates between different frames
 Coordinate Maps, Time-dependentFunctions for mapping time-dependent coordinates between different frames
 DataBoxDocumentation, functions, metafunctions, and classes necessary for using DataBox
 DataBox TagsStructures and metafunctions for labeling the contents of DataBoxes
 Data StructuresVarious useful data structures used in SpECTRE
 DG-SubcellFunctions and classes specific to the discontinuous Galerkin method supplemented with a finite volume or finite difference subcell limiter. Can also be thought of as a DG-FD hybrid method
 Discontinuous GalerkinFunctions and classes specific to the Discontinuous Galerkin algorithm
 Elliptic SystemsAll available elliptic systems
 Equations of StateThe various available equations of state
 Error HandlingMacros and functions used for handling errors
 Events and TriggersClasses and functions related to events and triggers
 Evolution SystemsAll available evolution systems and information on how to implement evolution systems
 ExecutablesA list of executables and how to use them
 File SystemA light-weight file system library
 Finite DifferenceFunctions needed for (conservative) finite difference methods
 General RelativityContains functions used in General Relativistic simulations
 HDF5Functions and classes for manipulating HDF5 files
 InitializationActions and metafunctions used for initialization of parallel components
 LimitersLimiters to control shocks and surfaces in the solution
 Linear SolverAlgorithms to solve linear systems of equations
 LoggingFunctions for logging progress of running code
 Math FunctionsUseful analytic functions
 Numerical AlgorithmsGeneric numerical algorithms
 Numerical FluxesThe set of available numerical fluxes
 ObserversObserving/writing data to disk
 Option GroupsTags used for grouping input file options
 Option ParsingThings related to parsing YAML input files
 Option TagsTags used for options parsed from the input file
 ParallelizationFunctions, classes and documentation related to parallelization and Charm++
 Performance, Efficiency, and OptimizationsClasses and functions useful for performance optimizations
 Pretty TypePretty printing of types
 ProtocolsClasses that define metaprogramming interfaces
 Python BindingsClasses and functions useful when writing python bindings
 Special RelativityContains functions used in special relativity calculations
 SpectralThings related to spectral transformations
 Spin-weighted spherical harmonicsUtilities, tags, and metafunctions for using and manipulating spin-weighted spherical harmonics
 SurfacesThings related to surfaces
 TensorTensor use documentation
 Tensor ExpressionsTensor Expressions allow writing expressions of tensors in a way similar to what is used with pen and paper
 Testing FrameworkClasses, functions, macros, and instructions for developing tests
 TimeCode related to the representation of time during simulations
 Time SteppersA collection of ODE integrators primarily used for time stepping
 Type TraitsA collection of useful type traits, including C++14 and C++17 additions to the standard library
 UtilitiesA collection of useful classes, functions and metafunctions
 Variable FixingA collection of different variable fixers ranging in sophistication