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.
A free alternative to Marvin JS and MarvinSketch
Free individual academic licences for Marvin ended on 31 July 2026, and Marvin JS is not sold after 2026 and reaches end of life at the end of 2027. Covalent is free, needs no licence or account, and runs in any modern browser.
Marvin compared with Covalent
| What you need | Marvin | Covalent |
|---|---|---|
| Price | Paid subscription; free academic licences ended in July 2026 | Free |
| In the browser | Marvin subscription, 14-day trial | Yes |
| Windows, macOS and Linux | Yes | Yes |
| Account needed | Licence or subscription | No |
| Bond, ring and chain tools | Yes | Yes |
| Wedged and hashed bonds | Yes | Yes |
| R/S and E/Z labels | Yes | Yes |
| Valence check | Marks errors after drawing | Refuses as you draw |
| Paste SMILES or a MOL block | Yes | Yes |
| Export MOL, SVG and PNG | Yes | Yes |
| Insert a compound by name | With a naming licence | From a 48,000-compound database |
| Reaction arrows and conditions | Yes | With reaction SMILES and RXN files |
| pKa, logP and other predictions | Calculator plugins, licensed | Separate drug-likeness tool |
Marvin remains the stronger choice for cheminformatics: Chemaxon's calculators for pKa, logP and tautomers, structure-based naming, and an editor built to be embedded in other web applications. Covalent is a drawing tool for chemists who need structures, schemes and pages, for free.
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
Is there still a free academic Marvin licence?
No. Chemaxon discontinued free individual academic licences in May 2026, and access ended on 31 July 2026. Marvin is now a paid subscription with a 14-day trial.
What happens to Marvin JS?
Marvin JS 25 is the final version: it is not sold after 31 December 2026 and reaches end of life on 31 December 2027. Chemaxon's successor is the Marvin subscription.
Can I bring my Marvin structures?
Yes. Export them from Marvin as MOL, SDF or SMILES and open the file in Covalent, or paste SMILES or a MOL block straight onto the canvas.