A Concentration-Response Modeling Utility R package tcplfit2 version 0.1.9 The tcplfit2 R package performs basic concentration-response curve fitting. The original tcplFit() function in the tcpl R package performed basic concentration-response curvefitting to 3 models. With tcplfit2, the core tcpl concentration-response functionality has been expanded to process diverse high-throughput screen (HTS) data generated at the US Environmental Protection Agency, including targeted ToxCast, high-throughput transcriptomics (HTTr) and high-throughput phenotypic profiling (HTPP). tcplfit2 can be used independently to support analysis for diverse chemical screening efforts. Software Depends: R (>= 3.5.0) Imports: stats, methods, numDeriv, RColorBrewer, stringr, reshape2, ggplot2 (>= 3.5.0) Suggests: knitr, rmarkdown, stringi, DT, data.table, tcpl, prettydoc, testthat (>= 3.0.0), here, htmlTable, tidyr, dplyr, gridExtra, rmdformats Madison Feshuk <feshuk.madison@epa.gov> Comprehensive R Archive Network (CRAN) Thomas Sheffield [aut], Jason Brown [ctb] (ORCID: <https://orcid.org/0009-0000-2294-641X>), Sarah E. Davidson-Fritz [ctb] (ORCID: <https://orcid.org/0000-0002-2891-9380>), Madison Feshuk [ctb, cre] (ORCID: <https://orcid.org/0000-0002-1390-6405>), Lindsay Knupp [ctb], Zhihui Zhao [ctb], Richard S Judson [ctb] (ORCID: <https://orcid.org/0000-0002-2348-9633>), Katie Paul Friedman [ctb] (ORCID: <https://orcid.org/0000-0002-2710-1691>) MIT + file LICENSE (https://CRAN.R-project.org/package=tcplfit2/LICENSE) 2025-07-23 application/tgz https://CRAN.R-project.org/package=tcplfit2 doi:10.32614/CRAN.package.tcplfit2