Bonds snap to chemistry
New bonds land on real bond angles: 120° zigzags, linear triple bonds and allenes, the free side of a ring atom. Rings fuse onto the bond you point at.
MolSketch, but in your browser
MolSketch is a capable free desktop editor, but it has to be downloaded and installed. Covalent runs the same everyday work in a browser tab: draw structures, insert compounds by name or CAS number, read the formula and molar mass live and export SMILES, MOL, SVG or PNG.
MolSketch compared with Covalent
| What you need | MolSketch | Covalent |
|---|---|---|
| Price | Free, open source | Free |
| Installation | Desktop program | None, runs in the browser |
| Managed Chromebooks and tablets | No | Yes |
| Bond, ring and chain tools | Yes | Yes |
| Wedged and hashed bonds | Yes | Yes |
| Bonds snap to real bond angles | Grid and angle steps | Snaps to the atom's free valence directions |
| Valence check while drawing | No | Yes |
| Insert a compound by name or CAS number | No | From a 48,000-compound database |
| Formula and molar mass while drawing | Yes | Yes |
| Export MOL, SVG and PNG | Yes | Yes |
MolSketch remains a good choice offline and on machines where you can install software. Covalent is built for everywhere else.
What Covalent does differently
Impossible structures are refused
A fifth bond to carbon or a double bond to a saturated nitrogen is stopped as you draw, with a plain explanation, instead of producing a structure no chemist can make.
Stereochemistry that round-trips
Wedges and hashes are read the way RDKit and the InChI library read them, and a structure opened from SMILES comes back with its stereocentres drawn.
Every compound in the database
Insert any of 48,000 compounds by name, CAS number or formula, or paste SMILES or a MOL block straight onto the canvas.
Whole documents, not just drawings
Lay out structures, text, arrows and answer lines on pages, start from a worksheet, exam, reaction scheme or group-meeting template, switch the whole document to ACS 1996 and download a PDF or paste it into Google Docs.
Common questions
Does Covalent work offline like MolSketch?
Yes. After one visit Covalent opens and draws without a connection, and Chrome and Edge install it as an app with its own window.
Can I bring my MolSketch drawings?
Save them from MolSketch as MOL files or copy SMILES, then open the file in Covalent or paste onto the canvas.