Sixteen codes were added in February 2018:

AntiparticleDM: Discriminating between Majorana and Dirac Dark Matter
ARTIP: Automated Radio Telescope Image Processing Pipeline
astroplan: Observation planning package for astronomers
BHMcalc: Binary Habitability Mechanism Calculator

CMacIonize: Monte Carlo photoionisation and moving-mesh radiation hydrodynamics
collapse: Spherical-collapse model code
eqpair: Electron energy distribution calculator
FAC: Flexible Atomic Code

Glimpse: Sparsity based weak lensing mass-mapping tool
HiGal_SED_Fitter: SED fitting tools for Herschel Hi-Gal data
mrpy: Renormalized generalized gamma distribution for HMF and galaxy ensemble properties comparisons
PyOSE: Orbital sampling effect (OSE) simulator

runDM: Running couplings of Dark Matter to the Standard Model
venice: Mask utility
Verne: Earth-stopping effect for heavy dark matter
VISIBLE: VISIbility Based Line Extraction

Sixteen codes were added in December 2017:

Bitshuffle: Filter for improving compression of typed binary data
CosApps: Simulate gravitational lensing through ray tracing and shear calculation
draco: Analysis and simulation of drift scan radio data
FBEye: Analyzing Kepler light curves and validating flares

Flux Tube: Solar model
KDUtils: Kinematic Distance Utilities
LgrbWorldModel: Long-duration Gamma-Ray Burst World Model
MadDM: Computation of dark matter relic abundance

MPI_XSTAR: MPI-based parallelization of XSTAR program
Nyx: Adaptive mesh, massively-parallel, cosmological simulation code
photodynam: Photodynamical code for fitting the light curves of multiple body systems
Py-SPHViewer: Cosmological simulations using Smoothed Particle Hydrodynamics

QATS: Quasiperiodic Automated Transit Search
RODRIGUES: RATT Online Deconvolved Radio Image Generation Using Esoteric Software
SFoF: Friends-of-friends galaxy cluster detection algorithm
SgrbWorldModel: Short-duration Gamma-Ray Burst World Model

And twelve codes were added in January 2018:

BANYAN_Sigma: Bayesian classifier for members of young stellar associations
BOND: Bayesian Oxygen and Nitrogen abundance Determinations
cambmag: Magnetic Fields in CAMB
DecouplingModes: Passive modes amplitudes

DICE/ColDICE: 6D collisionless phase space hydrodynamics using a lagrangian tesselation
GABE: Grid And Bubble Evolver
Gnuastro: GNU Astronomy Utilities
hh0: Hierarchical Hubble Constant Inference

InitialConditions: Initial series solutions for perturbations in our Universe
iWander: Dynamics of interstellar wanderers
RadVel: General toolkit for modeling Radial Velocities
Stan: Statistical inference

Twenty-three codes were added in November 2017:

BayesVP: Full Bayesian Voigt profile fitting
Bifrost: Stream processing framework for high-throughput applications
clustep: Initial conditions for galaxy cluster halo simulations
correlcalc: Two-point correlation function from redshift surveys
FATS: Feature Analysis for Time Series

FTbg: Background removal using Fourier Transform
galkin: Milky Way rotation curve data handler
galstep: Initial conditions for spiral galaxy simulations
galstreams: Milky Way streams footprint library and toolkit
Gammapy: Python toolbox for gamma-ray astronomy

HBT: Hierarchical Bound-Tracing
HBT+: Subhalo finder and merger tree builder
HO-CHUNK: Radiation Transfer code
inhomog: Raychaudhuri integration
LExTeS: Link Extraction and Testing Suite

Lightning: SED Fitting Package
MARXS: Multi-Architecture Raytrace Xray mission Simulator
megaman: Manifold Learning for Millions of Points
rac-2d: Thermo-chemical for modeling water vapor formation in protoplanetary disks
RGW: Affine-invariant Markov Chain Monte Carlo sampling

SpcAudace: Spectroscopic processing and analysis package of Audela software
SPIDERMAN: Fast code to simulate secondary transits and phase curves
Thindisk: Protoplanetary disk toy model

Twenty-five codes were added in October 2017:

ATLAS9: Model atmosphere program with opacity distribution functions
Binary: Accretion disk evolution
CppTransport: Two- and three-point function transport framework for inflationary cosmology
EXOFASTv2: Generalized publication-quality exoplanet modeling code
FITSFH: Star Formation Histories

FLaapLUC: Fermi-LAT automatic aperture photometry light curve
FLAG: Exact Fourier-Laguerre transform on the ball
FSFE: Fake Spectra Flux Extractor
galario: Gpu Accelerated Library for Analyzing Radio Interferometer Observations
GASOLINE: Smoothed Particle Hydrodynamics (SPH) code

GBART: Determination of the orbital elements of spectroscopic binaries
GMCALab: Generalized Morphological Component Analysis
LGMCA: Local-Generalized Morphological Component Analysis
LIMEPY: Lowered Isothermal Model Explorer in PYthon
MOSFiT: Modular Open-Source Fitter for Transients

mTransport: Two-point-correlation function calculator
OSIRIS Toolbox: OH-Suppressing InfraRed Imaging Spectrograph pipeline
pred_loggs: Predicting individual galaxy G/S probability distributions
PSPLINE: Princeton Spline and Hermite cubic interpolation routines
PyTransport: Calculate inflationary correlation functions

Ramses-GPU: Second order MUSCL-Handcock finite volume fluid solver
rfpipe: Radio interferometric transient search pipeline
SkyNet: Modular nuclear reaction network library
SPIPS: Spectro-Photo-Interferometry of Pulsating Stars
vysmaw: Fast visibility stream muncher

Ten codes were added to the ASCL in September 2017:

bmcmc: MCMC package for Bayesian data analysis
celerite: Scalable 1D Gaussian Processes in C++, Python, and Julia
DanIDL: IDL solutions for science and astronomy
DCMDN: Deep Convolutional Mixture Density Network
DOOp: DAOSPEC Output Optimizer pipeline

MagIC: Fluid dynamics in a spherical shell simulator
MeshLab: 3D triangular meshes processing and editing
MSSC: Multi-Source Self-Calibration
PHANTOM: Smoothed particle hydrodynamics and magnetohydrodynamics code
SPHYNX: SPH hydrocode for subsonic hydrodynamical instabilities and strong shocks

Seven codes were added to the ASCL in July 2017:

CCFpams: Atmospheric stellar parameters from cross-correlation functions
Gala: Galactic astronomy and gravitational dynamics
HRM: HII Region Models
pyaneti: Multi-planet radial velocity and transit fitting
PyMOC: Multi-Order Coverage map module for Python

SASRST: Semi-Analytic Solutions for 1-D Radiative Shock Tubes
swot: Super W Of Theta

And thirty codes were added to the ASCL in August 2017:

4DAO: DAOSPEC interface
ALCHEMIC: Advanced time-dependent chemical kinetics
ANA: Astrophysical Neutrino Anisotropy
Astroquery: Access to online data resources
ATOOLS: A command line interface to the AST library

BAGEMASS: Bayesian age and mass estimates for transiting planet host stars
CINE: Comet INfrared Excitation
ComEst: Completeness Estimator
CRISPRED: CRISP imaging spectropolarimeter data reduction pipeline
CUTEX: CUrvature Thresholding Extractor

DISORT: DIScrete Ordinate Radiative Transfer
empiriciSN: Supernova parameter generator
ExoSOFT: Exoplanet Simple Orbit Fitting Toolbox
extinction-distances: Estimating distances to dark clouds
FIEStool: Automated data reduction for FIber-fed Echelle Spectrograph (FIES)

GAMBIT: Global And Modular BSM Inference Tool
GANDALF: Gas AND Absorption Line Fitting
GMM: Gaussian Mixture Modeling
iSEDfit: Bayesian spectral energy distribution modeling of galaxies
KERTAP: Strong lensing effects of Kerr black holes

LCC: Light Curves Classifier
Naima: Derivation of non-thermal particle distributions through MCMC spectral fitting
PACSman: IDL Suite for Herschel/PACS spectrometer data
PBMC: Pre-conditioned Backward Monte Carlo code for radiative transport in planetary atmospheres
pyLCSIM: X-ray lightcurves simulator

RM-CLEAN: RM spectra cleaner
SINFONI Pipeline: Data reduction pipeline for the Very Large Telescope SINFONI spectrograph
STools: IDL Tools for Spectroscopic Analysis
TWO-POP-PY: Two-population dust evolution model
XDGMM: eXtreme Deconvolution Gaussian Mixture Modeling

Twelve codes were added to the ASCL in June 2017:

DaMaSCUS: Dark Matter Simulation Code for Underground Scatterings
Dark Sage: Semi-analytic model of galaxy evolution
encube: Large-scale comparative visualization and analysis of sets of multidimensional data
EXOSIMS: Exoplanet Open-Source Imaging Mission Simulator
Exotrending: Fast and easy-to-use light curve detrending software for exoplanets

GenPK: Power spectrum generator
KeplerSolver: Kepler equations solver
LMC: Logarithmantic Monte Carlo
PyPulse: PSRFITS handler
rtpipe: Searching for Fast Radio Transients in Interferometric Data

sick: Spectroscopic inference crank
the-wizz: Clustering redshift estimation code

Seventeen codes were added to the ASCL in May 2017:

astroABC: Approximate Bayesian Computation Sequential Monte Carlo sampler
COSMOS: Carnegie Observatories System for MultiObject Spectroscopy
DMATIS: Dark Matter ATtenuation Importance Sampling
demc2: Differential evolution Markov chain Monte Carlo parameter estimator
f3: Full Frame Fotometry for Kepler Full Frame Images

fd3: Spectral disentangling of double-lined spectroscopic binary stars
FDBinary: A tool for spectral disentangling of double-lined spectroscopic binary stars
getimages: Background derivation and image flattening method
LensPop: Galaxy-galaxy strong lensing population simulation
MBProj2: Multi-Band x-ray surface brightness PROJector 2

NPTFit: Non-Poissonian Template Fitting
PCAT: Probabilistic Cataloger
PROFILER: 1D galaxy light profile decomposition
PSOAP: Precision Spectroscopic Orbits A-Parametrically
SPTCLASS: SPecTral CLASSificator code

supernovae: Photometric classification of supernovae
WeirdestGalaxies: Outlier Detection Algorithm on Galaxy Spectra

Fourteen codes were added to the ASCL in April 2017:

A-Track: Detecting Moving Objects in FITS images
Difference-smoothing: Measuring time delay from light curves
Multipoles: Potential gain for binary lens estimation
Photo-z-SQL: Photometric redshift estimation framework
pwkit: Astronomical utilities in Python

PySM: Python Sky Model
Quickclump: Identify clumps within a 3D FITS datacube
Shwirl: Meaningful coloring of spectral cube data with volume rendering
STATCONT: Statistical continuum level determination method for line-rich sources
Transit: Radiative-transfer code for planetary atmospheres

UDAT: A multi-purpose data analysis tool
VaST: Variability Search Toolkit
VULCAN: Chemical Kinetics For Exoplanetary Atmospheres
XID+: Next generation XID development

Fifteen codes were added to the ASCL in March 2017:

Atmospheric Athena: 3D Atmospheric escape model with ionizing radiative transfer
Charm: Cosmic history agnostic reconstruction method
COCOA: Simulating Observations of Star Cluster Simulations
Corrfunc: Blazing fast correlation functions on the CPU
exorings: Exoring Transit Properties

ICICLE: Initial Conditions for Isolated CoLlisionless systEms
Larch: X-ray Analysis for Synchrotron Applications using Python
MC-SPAM: Monte-Carlo Synthetic-Photometry/Atmosphere-Model
PHOTOMETRYPIPELINE: Automated photometry pipeline
PyMVPA: MultiVariate Pattern Analysis in Python

QtClassify: IFS data emission line candidates classifier
sidm-nbody: Monte Carlo N-body Simulation for Self-Interacting Dark Matter
SNRPy: Supernova remnant evolution modeling
starsense_algorithms: Performance evaluation of various star sensors
TransitSOM: Self-Organizing Map for Kepler and K2 transits