SMILES-Mapper is a small web application that can be found at kyll.dk/SMILES-Mapper. SMILES-Mapper allows interactive visualization of how SMILES & InChi strings are created for a given molecule together with the V2000 ( used in .mol and .sdf files) and V3000 mol-blocks.
SMILES-Mapper was primarily made to learn RDKitJS, but hopefully, it can still be useful for debugging SMILES & InChi string, or as a teaching tool. SMILES-Mapper is open-source and released under an MIT license. However, if you use the code for something interesting, please cite this work and its author appropriately.