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Chemistry tools that think like a chemist.

Draw structures that snap to real bond angles, scale reactions, plan distillations and read spectra. In your browser, with the chemistry checked while you work.

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Covalent

A structure editor that snaps to real bond angles and checks valence and stereo as you draw. Lays out worksheets, exams and schemes on pages in ACS 1996 style, as PDF, and opens ChemDraw CDXML files.

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Signum

Open NMR, IR, UV-Vis and MS spectra and HPLC, GC and LC-MS chromatograms. Pick peaks, integrate, correct the baseline and overlay.

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Spectrum file converter

Read JCAMP-DX, SPC, OMNIC, PerkinElmer SP, Bruker OPUS and CSV spectra and ANDI, ChemStation and mzML chromatograms in the browser and export CSV, Excel, JCAMP-DX or ANDI.

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Draw structures

SMILES to structurePaste SMILES and get a clean skeletal formula, formula, mass and a 3D model. Download SVG, PNG, MOL or 3D SDF.

NMR and spectra

NMR predictorEstimate 1H and 13C chemical shifts and multiplicities from a structure, then open the spectrum in Signum.NMR solvent impuritiesWhich solvent, reagent or grease is that peak? Look up a ¹H or ¹³C shift in 12 deuterated solvents against the Gottlieb, Fulmer and Babij tables.

Reaction set-up and yield

Reaction scaleFix the amount of one reagent and get masses, volumes and moles for everything else from equivalents and density.StoichiometryBalance the equation, enter what you have, and see the limiting reagent, theoretical yield and excess.Equation balancerBalance any equation, including ions and redox half-reactions, with exact integer coefficients.Compound listPaste names, CAS numbers or SMILES and get one table with molar mass, physical data, pKa and GHS hazards, ready to copy or download.

Distillation and vacuum

Fractional distillationPredict the fractions a column will give: boiling points at your pressure, Fenske plates and azeotrope warnings.Pressure–temperature nomographBoiling point at any pressure for a named compound, or from one known boiling point.Vapour pressureVapour pressure curves from Antoine constants, with the normal boiling point marked.Pressure unitsConvert between mbar, Torr, mmHg, atm, bar, kPa and psi, the units found on vacuum gauges.

Molecular weight and properties

Molar massMolar mass, exact mass, elemental composition and the isotope pattern for any formula or structure.Drug-likenessLipinski, Veber, Ghose and lead-likeness from a structure, with every descriptor shown.Periodic tableAll 118 elements with masses, electron configurations, electronegativity and physical data.

Solutions, dilutions and pH

Solutions and dilutionsWhat to weigh for a molar solution, how much stock to dilute, and how to make 1 M HCl from 37 % acid.pH and bufferspH of acids, bases and buffers from exact equilibria, including polyprotic acids and mixtures.

Chemical inventory and safety

Chemical inventoryKeep the stock of a school, university or lab with GHS hazards, storage classes, expiry and low-stock warnings, and print the hazardous substances register.

Bonds snap to chemistry, not to a grid

Covalent places every new bond at a real bond angle: 120° zigzags, linear triple bonds, rings fused on the side you point at. Valence, charges and stereochemistry are checked while you draw, so an impossible structure never gets drawn.

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Spectra in, answers out

Open JCAMP-DX, Galactic or Shimadzu SPC, OMNIC, PerkinElmer SP, Bruker OPUS or CSV files from any instrument, pick peaks and integrate in Signum, predict 1H and 13C shifts from a structure, and convert everything to CSV or Excel without uploading a byte.

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Plan the bench work

Scale a reaction from the amount of one reagent, find the limiting reagent, work out a buffer, or see which fractions a distillation will give at your pressure, with boiling points from real Antoine data.

Reaction scale
48,985 compounds
Ibogaine83-74-9Ibogaine — naturally occurring indole alkaloid from the West African shrub Tabernanthe iboga, long used outside the US to interrupt opioid use disorder in a single multi-day dose. Psilocybin520-52-5Psilocybin — prodrug of psilocin, active in psilocybe mushrooms and the leading psychedelic candidate for FDA approval. Methylone186028-79-5Methylone (TSND-201) – β-keto analog of MDMA differing only by a single ketone insertion that eliminates 5-HT2A activity (so non-hallucinogenic) while preserving rapid-onset monoamine release. MDMA42542-10-9Midomafetamine (MDMA) – submitted to the FDA in 2024 as the first psychedelic to reach a PDUFA decision in modern history. Semaglutide910463-68-2Semaglutide – long-acting GLP-1 receptor agonist (Ozempic / Wegovy / Rybelsus) that reshaped weight management and type-2 diabetes care. Caffeine58-08-2The world's most-consumed psychoactive compound – a methylxanthine adenosine-receptor antagonist found in coffee, tea, and cocoa. Aspirin50-78-2Acetylsalicylic acid – the first mass-produced synthetic drug (Bayer, 1899) and an irreversible covalent inhibitor of cyclooxygenase via acetylation of COX-1 Ser530.

From the blog

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Cheminformatics file formats from 1971 to today

How molecules are stored on disk, from the PDB format and MDL molfiles to CIF, CML, CDXML and CXSMILES, with ethanol as the running example.

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48,985 compounds, 3,374 reactions, 20 tools.

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