Native C++ · offline · in development

Draw the structure.
Read the spectrum.

A chemical drawing program with the prediction stack inside it, instead of behind a server.
The editor is free, forever.
Your molecules never leave the machine.

Join the release list Free vs. paid

ETHYL ACETATEC₄H₈O₂¹H · 400 MHzPREDICTED

Nothing is uploaded

Everything runs locally. No account, no server round trip, no structure leaving your network.

Weights we own

Every shipped model is either permissively licensed or trained here from scratch on licence-checked data.

One executable

Dependency-light and statically linked. Install and run on any machine. No more python venvs.

Why ChemGraf

Free, offline, and yours to keep.

Free drawing programs you can install and keep are disappearing. What is left is a browser tab, a paid seat, or a toolkit that wants Python first. ChemGraf puts that kind of program back on the desktop: publication-grade drawings and spectra, nothing uploaded.

The editor is free and stays free: the whole drawing surface, the file formats, IUPAC names in both directions. No watermark, no account, no expiry.

The paid version adds the prediction stack and 3D conformers informing the spectra: a single payment with a lifetime licence, no subscription.

What is in it

The prediction stack is what you would be paying for

Drawing is free. The reason to buy is what happens after you draw — and all of it runs on your own machine.

Nuclei

¹H, ¹³C, ¹⁹F, ³¹P shifts. ⁿJ_HH, ⁿJ_FH and ⁿJ_FC couplings.

Real multiplets

Spin systems solved by exact diagonalisation, not additivity rules. A quartet is a quartet because the maths says so.

Conformers

ETKDG embedding and MMFF94s optimisation in the editor. Boltzmann-weighted ensembles feed the spectra.

Infrared

Own model, trained in house. Conformer-averaged rather than single-geometry.

Mass spectrometry

EI fragmentation and ESI-MS/MS, with bond dissociation energies informing the fragments.

Physicochemical

pK_a from rules, a GNN and Taft corrections. logP, molar refractivity, BDE, UV/Vis rules.

Steric fields

ASO and AEIF occupancy and charge vectors, pose-invariant, dumped as plain arrays.

Molecular passport

QED, synthetic accessibility, PAINS / Brenk / NIH / ZINC filters, Lipinski, Veber, Ghose, Egan, Muegge.

Still growing

The stack is the living half of the program. New property and reactivity predictions are added as they become available.

Free and paid

One program, two versions. The drawing half is free.

No trial, no cut-down demo: the free version is the same editor the paid one is built on.

ChemGraf

Free · forever · no account

The complete structure editor. Everything you need to draw a molecule and put it in a document.

The full canvas — bonds, rings, templates, stereo wedges, brackets, arrows, shapes, text
Multi-page sheets, alignment, z-order, clean-up layout
Every file format: CDXML, MOL/SDF (V2000 and V3000), SMILES, XYZ
Export to PNG, SVG and EMF; paste into Word or PowerPoint
IUPAC name to structure and structure to name
Formula, mass, exact mass, structure checking
No watermark, no page limit, no expiry, nothing uploaded

ChemGraf Pro

One payment · lifetime licence

Everything above, plus the prediction stack. Buy it once, at a price aimed at individuals rather than institutions.

¹H, ¹³C, ¹⁹F and ³¹P NMR with real spin-system simulation
Coupling constants and multiplets solved, not guessed from rules
3D view with conformers and MMFF94s minimisation
Infrared, conformer-averaged, from a model trained here
EI-MS fragmentation and ESI-MS/MS
pK_a, logP, molar refractivity, bond dissociation energies
Boltzmann-weighted conformer ensembles feeding the spectra
Medchem passport: QED, synthetic accessibility, PAINS and friends
Updates for the version you bought, without a renewal date

Two promises in writing. File formats will never move behind a paywall. And a lifetime licence means the copy you bought keeps working: no server call to check, so nothing can switch it off later.

The program

What it looks like

Screenshots of the program as it stands today, not mock-ups. Light and dark themes, a resizable tool strip, and an info panel that keeps the numbers next to the drawing.