ChemSearch is a chemistry reference app for Android. Search compounds by name, CAS number, formula, PubChem CID, or drawn structure. Open formulas, identifiers, 2D structures, 3D models, descriptions, synonyms, and GHS safety summaries when source data is available. The app also includes a periodic table, a built-in chemical database, offline compound saves, recent searches, favorites, compound comparison, and practical chemistry tools such as molar mass, empirical formula, pH/pOH, oxidation state, reaction balancing, precipitation, stoichiometry, dilution, gas laws, SMILES lookup, and a local 3D molecule viewer. Most chemistry data comes from public sources such as PubChem, Wikipedia, Wikimedia Commons, UNECE GHS pictograms, Bowserinator/Periodic-Table-JSON, and the NCI/CADD resolver. AI descriptions are optional and require the user to add their own API key for the chosen provider. These optional providers use non-free network services, so the F-Droid build is marked with the NonFreeNet anti-feature. Safety information is for quick reference only. Always follow the official SDS, lab rules, and local safety requirements for real handling decisions.