Flexible Synthetic Data for Nested, Longitudinal and Linked Multi-Table Data R package flexsynth version 0.2.1 Generates utility-oriented synthetic data for supported flat, nested, longitudinal and tree-linked multi-table designs, including patients, admissions, procedures and laboratory results linked by identifiers. The default engine uses sequential conditional synthesis; an opt-in differentially private engine implements person-level (epsilon, delta) mechanisms and records their budget accounting. Synthetic output is not anonymisation. Empirical utility and disclosure-risk diagnostics are descriptive and do not by themselves establish that a release is safe. Software Depends: R (>= 4.1) Imports: graphics, grDevices, parallel, stats, utils Suggests: testthat (>= 3.0.0), rpart, ranger, partykit, data.table, knitr, litedown Yee How Lau <lauyeehow1986@gmail.com> Comprehensive R Archive Network (CRAN) Yee How Lau [aut, cre] MIT + file LICENSE (https://CRAN.R-project.org/package=flexsynth/LICENSE) 2026-09-02 application/tgz https://CRAN.R-project.org/package=flexsynth doi:10.32614/CRAN.package.flexsynth