Branch at a single atomIsobutane has one branch point carrying three methyls. Write the /c layer, and watch how parentheses hold the branches rather than marking them.A basics exercise. What you write is compared with what the InChI engine generates for the same structure, with 3 hints if you want them.Convert a structure to its InChI and InChIKey and back, convert a whole CSV, XLSX or SDF file, learn how the identifier is derived, and practise writing its layers. The InChI engine is WebAssembly running in your browser, so the tool needs JavaScript — and nothing you open ever leaves your machine.

Convert — a structure in, an InChI out

Batch — a whole CSV, XLSX or SDF file

Tutorial — how an InChI is derived

Exercises — write the layers yourself

Cheatsheet — every layer in a table

Tests — the IUPAC regression corpora

Download — take the engine away

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openbabel.cheminfo.org — Convert a structure between any pair of chemical file formats.

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surge.cheminfo.org — Every constitutional isomer of a molecular formula.

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moles.cheminfo.org — Balance a reaction, and work out its mass composition.

inorganic.cheminfo.org — Name an inorganic compound, and write its formula.

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