Give a double bond its signThis is Z-but-2-ene, with the two methyls on the same side. Write its /b layer — remembering that the sign follows canonical numbers, not CIP priorities.A stereo 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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learn.cheminfo.org — Arrange the tools into a course and hand out its link.

vcl.cheminfo.org — Combine a core and fragments into a screened library.

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iupac-name.cheminfo.org — The IUPAC name of a structure, and the structure a name denotes.

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

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dbe.cheminfo.org — Count rings and double bonds from a formula or a structure.

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metabo.nmrium.com — Turn a batch of NMR spectra into a map of your samples.

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

tex.cheminfo.org — LaTeX formulas rendered to SVG or PNG from a URL.

lcao.cheminfo.org — Combine atomic orbitals into molecular ones.

regexp.cheminfo.org — Learn regular expressions in a live playground.

pdb.cheminfo.org — A fast look at any Protein Data Bank entry.

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equilibrium.cheminfo.org — Chemical equilibria: pH, speciation and titration curves.

polycarp.cheminfo.org — Predict the microstructure of a radical copolymerisation.

3d.cheminfo.org — Conformers in 3D from a structure you draw.

periodic-table.cheminfo.org — The periodic table, coloured, plotted and taken apart.

database.cheminfo.org — Query a real chemical dataset in SQL and in Mango.

symmetry.cheminfo.org — Find the symmetry of a molecule, a crystal or a pattern.

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atoms.cheminfo.org — Electrons, neutrons, Lewis structures and oxidation states.

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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