Twenty-seven codes were added to the ASCL in May, 2019:

Astrocut: Tools for creating cutouts of TESS images
Bandmerge: Merge data from different wavebands
beamModelTester: Model evaluation for fixed antenna phased array radio telescopes
Binospec: Data reduction pipeline for the Binospec imaging spectrograph
CASI-2D: Convolutional Approach to Shell Identification – 2D

ClusterPyXT: Galaxy cluster pipeline for X-ray temperature maps
evolstate: Assign simple evolutionary states to stars
FastPM: Scaling N-body Particle Mesh solver
Fermitools: Fermi Science Tools
Fitsverify: FITS file format-verification tool

Grizli: Grism redshift and line analysis software
HAOS-DIPER: HAO Spectral Diagnostic Package For Emitted Radiation
LensCNN: Gravitational lens detector
LensQuEst: CMB Lensing QUadratic Estimator
MMIRS-DRP: MMIRS Data Reduction Pipeline

NAPLES: Numerical Analysis of PLanetary EncounterS
ODEPACK: Ordinary differential equation solver library
PICASO: Planetary Intensity Code for Atmospheric Scattering Observations
Prospector: Stellar Population inference from spectra and SEDs
Py4CAtS: PYthon for Computational ATmospheric Spectroscopy

PyPDR: Chemistry, thermal balance, and molecular excitation code
Q3C: A PostgreSQL package for spatial queries and cross-matches of large astronomical catalogs
rPICARD: Radboud PIpeline for the Calibration of high Angular Resolution Data
SEDPY: Modules for storing and operating on astronomical source spectral energy distribution
SICON: Stokes Inversion based on COnvolutional Neural networks

SPARK: K-band Multi Object Spectrograph data reduction
THALASSA: Orbit propagator for near-Earth and cislunar space

Thirty codes were added to the ASCL in April, 2019:

AutoBayes: Automatic design of customized analysis algorithms and programs
CausticFrog: 1D Lagrangian Simulation Package
CDAWeb: Coordinated Data Analysis Web
CGS: Collisionless Galactic Simulator
CLEAR: CANDELS Ly-alpha Emission at Reionization processing pipeline and library

covdisc: Disconnected covariance of 2-point functions in large-scale structure of the Universe
deproject: Deprojection of two-dimensional annular X-ray spectra
dfitspy: A dfits/fitsort implementation in Python
digest2: NEO binary classifier
ehtim: Imaging, analysis, and simulation software for radio interferometry

EightBitTransit: Calculate light curves from pixel grids
eleanor: Extracted and systematics-corrected light curves for TESS-observed stars
FortesFit: Flexible spectral energy distribution modelling with a Bayesian backbone
GALAXY: N-body simulation software for isolated, collisionless stellar systems
JVarStar: Variable Star Analysis Library

nbodykit: Massively parallel, large-scale structure toolkit
nudec_BSM: Neutrino Decoupling Beyond the Standard Model
OoT: Out-of-Transit Light Curve Generator
Properimage: Image coaddition and subtraction
pyRSD: Accurate predictions for the clustering of galaxies in redshift-space in Python

rate: Reliable Analytic Thermochemical Equilibrium
repack: Repack and compress line-transition data
SARAH: SUSY and non-SUSY model builder and analyzer
SBGAT: Small Bodies Geophysical Analysis Tool
simuTrans: Gravity-darkened exoplanet transit simulator

SMILI: Sparse Modeling Imaging Library for Interferometry
Specstack: A simple spectral stacking tool
sxrbg: ROSAT X-Ray Background Tool
TP2VIS: Total Power Map to Visibilities
Vevacious: Global minima of one-loop effective potentials generator

Twelve codes were added to the ASCL in February, 2019:

dyPolyChord: Super fast dynamic nested sampling with PolyChord
ExPRES: Exoplanetary and Planetary Radio Emissions Simulator
GraviDy: Gravitational Dynamics
LiveData: Data reduction pipeline

LPNN: Limited Post-Newtonian N-body code for collisionless self-gravitating systems
PINT: High-precision pulsar timing analysis package
PyMF: Matched filtering techniques for astronomical images
Radynversion: Solar atmospheric properties during a solar flare

RPFITS: Routines for reading and writing RPFITS files
SNTD: Supernova Time Delays
Specutils: Spectroscopic analysis and reduction
SpecViz: 1D Spectral Visualization Tool

And sixteen codes were added to the ASCL in March, 2019:

allesfitter: Flexible star and exoplanet inference from photometry and radial velocity
AsPy: Aspherical fluctuations on the spherical collapse background
brutifus: A Python module to post-process datacubes from integral field spectrographs
DAVE: Discovery And Vetting of K2 Exoplanets

GalIMF: Galaxy-wide Initial Mass Function
Galmag: Computing realistic galactic magnetic fields
HelioPy: Heliospheric and planetary physics library
ICSF: Intensity Conserving Spectral Fitting

NFWdist: Density, distribution function, quantile function and random generation for the 3D NFW profile
NIFTy5: Numerical Information Field Theory v5
PLATON: PLanetary Atmospheric Transmission for Observer Noobs
PRF: Probabilistic Random Forest

SimSpin: Kinematic analysis of galaxy simulations
SIXTE: Simulation of X-ray Telescopes
SPICE: Observation Geometry System for Space Science Missions
SpiceyPy: Python wrapper for the NAIF C SPICE Toolkit

Twelve codes were added to the ASCL in January, 2019:

bettermoments: Line-of-sight velocity calculation
Bilby: Bayesian inference library
CCL: Core Cosmology Library
cFE: Core Flight Executive

eddy: Extracting Disk DYnamics
Galaxia_wrap: Galaxia wrapper for generating mock stellar surveys
OCFit: Python package for fitting of O-C diagrams
Photon: Python tool for data plotting

SEDobs: Observational spectral energy distribution simulation
ssos: Solar system objects detection pipeline
stellarWakes: Dark matter subhalo searches using stellar kinematic data
unwise_psf: PSF models for unWISE coadds

Eighteen codes were added to the ASCL in December 2018:

aesop: ARC Echelle Spectroscopic Observation Pipeline
AUTOSPEC: Automated Spectral Extraction Software for integral field unit data cubes
distlink: Minimum orbital intersection distance (MOID) computation library
easyaccess: SQL command line interpreter for astronomical surveys
ExoGAN: Exoplanets Generative Adversarial Network

Fermipy: Fermi-LAT data analysis package
galclassify: Stellar classifications using a galactic population synthesis model
GENGA: Gravitational ENcounters with Gpu Acceleration
GLADIS: GLobal Accretion Disk Instability Simulation
GRAND-HOD: GeneRalized ANd Differentiable Halo Occupation Distribution

Juliet: Transiting and non-transiting exoplanetary systems modelling tool
Lightkurve: Kepler and TESS time series analysis in Python
OctApps: Octave functions for continuous gravitational-wave data analysis
PFANT: Stellar spectral synthesis code
psrqpy: Python module to query the ATNF pulsar catalogue

PynPoint 0.6.0: Pipeline for processing and analysis of high-contrast imaging data
SPAMCART: Smoothed PArticle Monte CArlo Radiative Transfer
WISP: Wenger Interferometry Software Package

Twenty codes were added to the ASCL in November 2018:

binaryBHexp: On-the-fly visualizations of precessing binary black holes
DiskSim: Modeling Accretion Disk Dynamics with SPH
DRAGONS: Gemini Observatory data reduction platform
Flame: Near-infrared and optical spectroscopy data reduction pipeline
gdr2_completeness: GaiaDR2 data retrieval and manipulation

MillCgs: Searching for Compact Groups in the Millennium Simulation
muLAn: gravitational MICROlensing Analysis Software
PENTACLE: Large-scale particle simulations code for planet formation
PulsarHunter: Searching for and confirming pulsars
pygad: Analysing Gadget Simulations with Python

Pylians: Python libraries for the analysis of numerical simulations
QuickSip: Project survey image properties onto the sky into Healpix maps
radon: Streak detection using the Fast Radon Transform
RLOS: Time-resolved imaging of model astrophysical jets
SEP: Source Extraction and Photometry

Shark: Flexible semi-analytic galaxy formation model
SIM5: Library for ray-tracing and radiation transport in general relativity
synphot: Synthetic photometry using Astropy
VoigtFit: Absorption line fitting for Voigt profiles
Vplanet: Virtual planet simulator

Twenty-one codes were added to the ASCL in October 2018:

APPLawD: Accurate Potentials in Power Law Disks
ARTES: 3D Monte Carlo scattering radiative transfer in planetary atmospheres
Barcode: Bayesian reconstruction of cosmic density fields
catsHTM: Catalog cross-matching tool
cuFFS: CUDA-accelerated Fast Faraday Synthesis

DDS: Debris Disk Radiative Transfer Simulator
Echelle++: Generic spectrum simulator
Eclairs: Efficient Codes for the LArge scales of the unIveRSe
Firefly: Interactive exploration of particle-based data
galfast: Milky Way mock catalog generator

GiRaFFE: General relativistic force-free electrodynamics code
JETGET: Hydrodynamic jet simulation visualization and analysis
MIEX: Mie scattering code for large grains
ODTBX: Orbit Determination Toolbox
pycraf: Spectrum-management compatibility

PyUltraLight: Pseudo-spectral Python code to compute ultralight dark matter dynamics
SOPHISM: Software Instrument Simulator
STARRY: Analytic computation of occultation light curves
STiC: Stockholm inversion code
VaeX: Visualization and eXploration of Out-of-Core DataFrames

XCLASS: eXtended CASA Line Analysis Software Suite

Sixteen codes were added to the ASCL in September 2018:

dynesty: Dynamic Nested Sampling package
Isca: Idealized global circulation modeling
LEMON: Differential photometry pipeline
MrMoose: Multi-Resolution Multi-Object/Origin Spectral Energy distribution fitting procedure

NEBULA: Radiative transfer code of ionized nebulae at radio wavelengths
nestcheck: Nested sampling calculations analysis
PASTA: Python Astronomical Stacking Tool Array
PCCDPACK: Polarimetry with CCD

perfectns: “Perfect” dynamic and standard nested sampling for spherically symmetric likelihoods and priors
PyQSOFit: Python code to fit the spectrum of quasars
qp: Quantile parametrization for probability distribution functions
RequiSim: Variance weighted overlap calculator

spops: Spinning black-hole binary population synthesis
stepped_luneburg: Stacked-based ray tracing code to model a stepped Luneburg lens
surfinBH: Surrogate final black hole properties for mergers of binary black holes
VBBINARYLENSING: Microlensing light-curve computation

Eleven codes were added to the ASCL in August 2018:

2DSF: Vectorized Structure Function Algorithm
Barycorrpy: Barycentric velocity calculation and leap second management
CPF: Corral Pipeline Framework
Fips: An OpenGL based FITS viewer
hfof: Friends-of-Friends via spatial hashing

hi_class: Horndeski in the Cosmic Linear Anisotropy Solving System
ImPlaneIA: Image Plane Approach to Interferometric Analysis
py-sdm: Support Distribution Machines
PyMieDap: Python Mie Doubling Adding Program
Robbie: Radio transients and variables detection workflow

rsigma: Resonant disturbance

Thirty-three codes were added to the ASCL in July 2018:

AngPow: Fast computation of accurate tomographic power spectra
ARKCoS: Radial kernel convolution on the sphere
ASP: Ames Stereo Pipeline
BARYCORR: Python interface for barycentric RV correction
CAESAR: Compact And Extended Source Automated Recognition

CLASSgal: Relativistic cosmological large scale structure code
DAMOCLES: Monte Carlo line radiative transfer code
EVEREST: Tools for de-trending stellar photometry
GLS: Generalized Lomb-Scargle periodogram
HELIOS: Radiative transfer code for exoplanetary atmospheres

HII-CHI-mistry_UV: Oxygen abundance and ionizionation parameters for ultraviolet emission lines
HII-CHI-mistry: Oxygen abundance and ionizionation parameters for optical emission lines
kplr: Tools for working with Kepler data using Python
ktransit: Exoplanet transit modeling tool in python
LSC: Supervised classification of time-series variable stars

MAPPINGS V: Astrophysical plasma modeling code
MIDLL: Markwardt IDL Library
nfield: Stochastic tool for QFT on inflationary backgrounds
NRPy+: Code generator for Numerical Relativity
POLARIS: POLArized RadIation Simulator

POWER: Python Open-source Waveform ExtractoR
PUMA: Low-frequency radio catalog cross-matching
PyAutoLens: Strong lens modeling
pyqz: Emission line code
SENR: Simple, Efficient Numerical Relativity

SPEGID: Single-Pulse Event Group IDentification
SSMM: Slotted Symbolic Markov Modeling for classifying variable star signatures
TBI: Three-Body Integration
THOR: Global Circulation Model for planetary atmospheres
Warpfield: Winds And Radiation Pressure: Feedback Induced Expansion, colLapse and Dissolution

wdmerger: Simulate white dwarf mergers with CASTRO
xGDS: Exploration Ground Data Systems
ZBARYCORR: Barycentric redshift calculator