A structure editor that opens .cdx and .cdxml

Draw molecules and reaction schemes in your browser. MolQuill opens and saves .cdx, .cdxml, molfile, SDF, RXN and SMILES, and uses ACS Document 1996 settings by default.

Open MolQuill Desktop app, $20 Free in the browser. No account needed.
Files are read locally and never uploaded.

A CBS reduction drawn in MolQuill and exported as SVG at the default settings.

The MolQuill window: menu bar, a tool palette down the left edge, a reaction scheme drawn on a white canvas, a docked panel at the right with the ring template library above a live analysis readout, and a status bar along the bottom showing the molecular formula, molecular weight, atom count and bond count. — The editor. Formula, exact mass, molecular weight and m/z update as you draw.

Features

Drawing style: ACS Document 1996 by default (14.4 pt bonds, 0.6 pt lines). RSC, Wiley and presentation styles are included.
Stereochemistry: Wedge and hash bonds, with R/S and E/Z labels on request.
Reactions: Arrows with reagents and conditions, equilibrium arrows, plus signs, brackets and curved arrows.
Name to structure: Type an IUPAC name such as (R)-2-butanol and get the structure, stereochemistry included.
Templates: Rings, functional groups, amino acids and sugars, including chair and boat cyclohexanes.
Analysis: Formula, exact mass, molecular weight, m/z and elemental analysis for the whole drawing or a selection.
Files: Open and save CDXML, CDX, molfile (V2000 and V3000), SDF, RXN and SMILES. Export SVG and PNG up to 600 dpi.

Oseltamivir, saved to a binary .cdx file and reopened.

Desktop app

The browser version is free and has every feature. The desktop app costs $20 as a one-time purchase and adds regular file handling: native Open and Save dialogs, Ctrl+S saving back to the same file, double-click to open .cdx files, a recent files list, and offline use.

One purchase covers Linux, Windows and macOS. There is no activation or license server.

Payment is handled by Stripe's Link checkout, and you are taken straight to a download page when it goes through. Bookmark that page: it keeps working for every 1.x version. Questions first? Email purchase@molquill.com.

Known limitations

MolQuill is written and maintained by one person.

Structure to name is in beta. It covers chains, carbon rings, bridged rings and 131 common ring systems (pyridine, indole, quinoline, pyrene and others), with one kind of main functional group. Steroids, large fused ring systems and phosphorus compounds are not named yet; for anything it cannot name it says so, and can ask PubChem instead.
The Windows and macOS installers are unsigned, so the operating system will show a warning the first time you open them.

Feedback

Bug reports are welcome, especially files that open incorrectly. Send them to bugreport@molquill.com.