Draw Molecules Without Installing Anything
MolSketch is a capable free desktop editor — but it is a Qt application you have to download and install. Covalent runs the same everyday workflow in a single browser tab: draw structures, insert molecules by name or CAS number, read formula and weight live, export SMILES.
Launch CovalentMolSketch (desktop) vs Covalent (browser)
| Feature | MolSketch | Covalent |
|---|---|---|
| Price | Free (open source) | Free |
| Installation | Desktop download + install | None — one ~60 KB page load |
| Works on managed Chromebooks | Only via Linux mode, which school fleets rarely enable | Yes — it's just a web page |
| Account required | No | No |
| Insert structure by name or CAS | No built-in lookup | Yes — searches 48,593 molecules as you type |
| Bond drawing tools | Single, double, triple, wedge, dash | Single, double, triple, aromatic, wedge, dash |
| Formula & weight while drawing | Basic | Live — plus exact mass and atom/bond counts |
| Drug-likeness (Lipinski, Veber) | No | Built-in, updates as you draw |
| SMILES input & export | Via optional OpenBabel setup | Built-in — round-trips verified against RDKit |
| MOL file import | Yes | Yes (plus JSON, SVG, PNG export) |
| Image-to-structure (OCR) | Via optional OSRA integration | No |
| 3D viewer | No | No — 2D only |
Honesty notes: MolSketch is good software and stays fully free offline — if you need OCR structure import or you work without a network, it remains the better fit. Covalent's edge is zero-install access and the name/CAS search backed by Chempirical's molecule database.
Type a Name, Get a Structure
Type "aspirin" or "58-08-2" into the search bar and the full structure lands on the canvas, laid out and editable — no redrawing textbook molecules ring by ring.
Chromebook-Proof
Desktop MolSketch needs an install — on school-managed Chromebooks that usually means a locked-down Linux mode you can't enable. Covalent opens like any web page.
Chemistry, Not Just Sketching
Formula, molecular weight, exact mass and Lipinski drug-likeness update live while you draw, and the SMILES you export parses cleanly in RDKit.