PLIP is a fully automated web service for detecting and visualizing non-covalent protein-ligand interactions in 3D structures. It is freely available at projects.biotec.tu-dresden.de/plip-web and can be used with protein data bank (PDB) structures, protein or ligand names, or custom protein-ligand complexes. The tool uses a rule-based algorithm to identify interactions such as hydrogen bonds, hydrophobic contacts, π-stacking, π-cation interactions, salt bridges, water bridges, and halogen bonds. PLIP provides publication-ready images, PyMOL session files, and parable result files for further processing. The full Python source code is available for download, and the command-line mode allows for high-throughput interaction profiling. PLIP is complementary to other state-of-the-art web tools and can be used for evaluating docking results, drug design, binding site similarity assessment, and drug repositioning. The web service allows for comprehensive detection and visualization of protein-ligand interaction patterns from 3D structures, either directly from the PDB or user-provided structures. Results are provided as 3D interaction diagrams, tables with interaction details, and downloadable result files. All interactions are listed at the atom level, enabling detailed analysis of specific binding characteristics. PLIP's algorithm involves four steps: structure preparation, functional characterization, rule-based matching, and filtering of interactions. The tool uses OpenBabel for internal representation of molecules and chemoinformatic calculations. It includes a blacklist to exclude preparation artifacts, modified residues, ions, and solvent compounds as ligands. The analysis is exemplified by the Bacillus subtilis DegV protein binding palmitic acid. PLIP includes a test suite with 30 literature-validated examples, covering diverse cases of protein-ligand complexes from the PDB. The standard thresholds of PLIP have been adapted to account for a broad range of interaction geometries. Users are encouraged to use these cases for testing and to contribute additional examples. PLIP can be used for structures from the PDB archive and structure files from other tools, enabling integration into pipelines for analyses related to protein-ligand binding. Examples include docking post-processing and inhibitor design. PLIP helps identify key residues and interaction patterns in different inhibitors, providing insights into their binding mechanisms. The tool is the first web service to provide comprehensive analysis and visualization of non-covalent protein-ligand interactions with one-click loading of structures.PLIP is a fully automated web service for detecting and visualizing non-covalent protein-ligand interactions in 3D structures. It is freely available at projects.biotec.tu-dresden.de/plip-web and can be used with protein data bank (PDB) structures, protein or ligand names, or custom protein-ligand complexes. The tool uses a rule-based algorithm to identify interactions such as hydrogen bonds, hydrophobic contacts, π-stacking, π-cation interactions, salt bridges, water bridges, and halogen bonds. PLIP provides publication-ready images, PyMOL session files, and parable result files for further processing. The full Python source code is available for download, and the command-line mode allows for high-throughput interaction profiling. PLIP is complementary to other state-of-the-art web tools and can be used for evaluating docking results, drug design, binding site similarity assessment, and drug repositioning. The web service allows for comprehensive detection and visualization of protein-ligand interaction patterns from 3D structures, either directly from the PDB or user-provided structures. Results are provided as 3D interaction diagrams, tables with interaction details, and downloadable result files. All interactions are listed at the atom level, enabling detailed analysis of specific binding characteristics. PLIP's algorithm involves four steps: structure preparation, functional characterization, rule-based matching, and filtering of interactions. The tool uses OpenBabel for internal representation of molecules and chemoinformatic calculations. It includes a blacklist to exclude preparation artifacts, modified residues, ions, and solvent compounds as ligands. The analysis is exemplified by the Bacillus subtilis DegV protein binding palmitic acid. PLIP includes a test suite with 30 literature-validated examples, covering diverse cases of protein-ligand complexes from the PDB. The standard thresholds of PLIP have been adapted to account for a broad range of interaction geometries. Users are encouraged to use these cases for testing and to contribute additional examples. PLIP can be used for structures from the PDB archive and structure files from other tools, enabling integration into pipelines for analyses related to protein-ligand binding. Examples include docking post-processing and inhibitor design. PLIP helps identify key residues and interaction patterns in different inhibitors, providing insights into their binding mechanisms. The tool is the first web service to provide comprehensive analysis and visualization of non-covalent protein-ligand interactions with one-click loading of structures.