Draw a molecule, get LaTeX

A free online chemical structure editor that writes chemfig — the LaTeX package chemists already use — so the structure you draw goes straight into a report, onto a web page, or into an exercise that asks your students to finish it.

chemfig LaTeX
SVG
PNG
220+ structures
Web pages
Exercises

Open the full editor →

One drawing, wherever it is going

Most free drawers give you a picture. This gives you the structure as a line of LaTeX as well, and the LaTeX is what travels: into a document, onto a page, into a lesson.

Into your LaTeX report

Copy LaTeX gives you chemfig. Add the package to your preamble and paste: the structure is typeset with the rest of your document, and stays editable as text.

\usepackage{chemfig}
…
\chemfig{H_3C-C(=[1]O)-[7]OH}

Onto a web page

fxTeX Server draws any structure from a URL, as a sharp SVG, with nothing to install — free for light use. With fxTeX Pro, the page itself holds the chemfig and the reader’s browser draws it.

Ethanoic acid — `fxtex.codecogs.com/svg.image?\chemfig{H_3C-C(=[1]O)-[7]OH}`

Into slides and worksheets

Download SVG or PNG for Word, PowerPoint, Google Docs or anywhere that takes a picture. Keep the LaTeX, and you can change the drawing and download it again later.

A drawing that asks a question

Leave an atom out, or leave a box beside the structure, and the drawing becomes an exercise: only the boxes take typing, and what is typed can be read back and marked. Try these.

Finish the molecule

Ethanol is missing two atoms.

Name the bond

What joins the two carbons?

Name the group

What makes this an acid?

Make your own: in the Structure Editor, select an atom and tick A box to fill in, or write {} in the LaTeX where the answer goes. On your own site, the editor’s structure lock lets students type only in the boxes and reads back what they wrote. Teachers using fxQuiz, now in early access, draw structures into quiz questions with the same editor.

Coming from FreeChemDraw, MolDraw or the RCSB sketcher?

All four draw a structure for free in the browser. They differ in what you can do with it afterwards — and where the others are ahead, we say so.

	fxEditor	FreeChemDraw	MolDraw	RCSB Chemical Sketch
Drawing
Draw with the mouse, free	Yes	Yes	Yes	Yes
Start from a known structure	220+ in a library	From its name	Name search	SMILES, InChI or ligand code
Structure, reaction and maths together	Yes	—	—	—
What you take away
LaTeX (chemfig) for a report	Yes	—	—	—
An image, SVG or PNG	Both	Both	PNG	—
An image from a URL, for a web page	Yes	—	—	—
Fill-in exercises for students	Yes	—	—	—
Where they are ahead
SMILES and MOL files	Not yet	Yes	SDF out	SMILES and InChI in
3D view	Not yet	Yes	Yes	—
Search the Protein Data Bank	—	—	—	Yes

The others as their own pages described them in November 2026. If you need SMILES, a 3D model or a search of the PDB, they are the better tools for that. If the structure is going into a document, a web page or a lesson, this is.

Drawing, not typing

You never need to read the chemfig. The Chemistry Structure Editor draws with the mouse and writes it for you; open it from the button above, or from the first button of the chemistry toolbar.

The tools you expect

Single, double and triple bonds; wedges and hashes; rings of any size, benzene, fused rings; charges, lone pairs and atom labels. Chains zig-zag by themselves, and a bond check flags an atom with too many bonds.

A library to start from

Over 220 molecules, rings and functional groups, found by name, formula or abbreviation: caffeine, COOH, Phe. Click one to start a drawing, or to attach it to the atom you have selected.

Change it later

A structure stays a structure: click its bonds in the equation to open it again, change it, and update. The full guide to chemfig and the editor →

The Chemistry Structure Editor: a tool strip on the left, aspirin drawn in the middle with its OH selected, and the Edit tab of the side panel on the right — The Chemistry Structure Editor, editing aspirin: 1 zoom and close, 2 the tools, 3 the drawing, 4 settings and the library, 5 the whole structure, 6 the selected atom — with its *box to fill in* — and 7 Update, to put it in the equation.

Questions

Will the LaTeX work in my own document?

It is chemfig, the package LaTeX documents use for structures: add \usepackage{chemfig} to the preamble and paste. Reactions written with \ce need \usepackage[version=4]{mhchem} too.

Can it open SMILES or MOL files?

Not yet. Start from the library of over 220 structures, or draw it; the tools above that read and write those files are better for that today.

How do I put structures on my website?

Use an image from fxTeX Server: the structure’s LaTeX in the URL of an <img>, free for light use and licensed beyond it. With a Professional or Enterprise licence, fxTeX Pro draws the chemfig in the page itself.

What about reactions and formulae?

The same editor writes those too, with mhchem: \ce{2H2 + O2 -> 2H2O}. Chemistry equations →

Is it free?

Yes, for non-commercial use: study, teaching, research, or a personal site. Structures made as part of work you sell — a book, a course, a product — need a licence. How licensing works.

FreeChemDraw, MolDraw and RCSB PDB are the names of their owners’ tools. CodeCogs is not affiliated with any of them.

Try it on the real thing

The full editor is on the home page, with suggestions as you type, history and every export format. It is free for non-commercial use — study, teaching, research or a personal site. Building it into something you sell needs a commercial licence.

Open the editor See licences