SynthBench is a free chemical structure editor that gives you the IUPAC name, molecular formula, molar mass, exact mass and GHS safety data as you draw — no account, no installation, works offline.
Open the free editor →Professional structure drawing has quietly become expensive. SynthBench keeps the essential part open: draw any molecule and immediately read its IUPAC name, molecular formula, molar mass, exact mass and elemental analysis. Search compounds by name, CAS number or SMILES. Check GHS hazard data. Use the periodic table and the calculators. All of it, without an account.
Draw molecules with a full-featured editor (JSME). Paste SMILES, load by name or CAS number, or start from a template.
Local systematic naming where the built-in rules apply, with online PubChem enrichment when available.
Molecular formula, molar mass, monoisotopic mass and elemental composition, updated live.
Hazard statements and pictograms pulled from public databases, with reagent data sheets.
Multi-step retrosynthetic routes with reliability scoring, indicative conditions and building-block availability.
Virtual flask: combine reagents and conditions, see likely products, by-products and blocked pathways.
Predicted 1H NMR, IR bands and UV-Vis estimates straight from a structure.
Detects ionisable groups from a structure and estimates pKa, with practical pH windows for extraction.
Dilutions, yields, solvent selection, distillation and TLC tools. Camera colorimetry remains a beta feature.
Chemistry students — check nomenclature, compute masses and understand reaction
mechanisms without paying for a licence.
Teachers — a tool students can open in one click, in class or at home.
Synthetic chemists — explore disconnections, check functional-group compatibility and
prepare experiments faster.
| Feature | Découverte | Pro | Pro Lab |
|---|---|---|---|
| Structure editor, IUPAC name, masses | ✓ Unlimited | ✓ | ✓ |
| Periodic table, calculators, reagent sheets | ✓ | ✓ | ✓ |
| Compound search (name / CAS / SMILES) | ✓ | ✓ | ✓ |
| Multi-step retrosynthesis | 3/day | ✓ Unlimited | ✓ Unlimited |
| Reaction prediction (virtual flask) | 1/day | 1/day | ✓ Unlimited |
| Mesomerism, stability & degradation | — | ✓ | ✓ |
| Advanced analytical tools / GUM | — | — | ✓ |
Pro from CHF 149/year, Pro Lab from CHF 249/year. A 7-day Pro Lab trial is available without a payment method.
Deeper explanations (in French):
How to find a molecule's IUPAC name
Understanding and using retrosynthesis
Student rate: Pro Lab at CHF 49/year with proof of enrolment — write to synthbench.win@outlook.com.
No. The structure editor, IUPAC naming, mass calculations, periodic table and calculators work immediately, without signing up.
The free tier is permanent, not a trial. Paid plans add computation-heavy modules (higher daily limits and advanced analysis) while the free tier keeps a permanent discovery quota.
The editor, naming and calculators run in your browser and keep working without a connection. Server-side modules and compound search need internet access.
Routes are generated from curated reaction rules and scored for reliability, convergence and building-block availability. They are theoretical suggestions for study and planning — not validated protocols. Always verify feasibility, safety and legality before any practical work.
An Android version is in closed testing. The web app already works on phones and tablets.