Draw molecules.
Ask AI about them.
Stop switching between your structure editor and AI tools. Draw molecules and explore their properties, reactions, and synthesis routes — all in one place.
How AI-Powered Chemical Structure Drawing Works
Draw your molecule
Use the professional structure editor with keyboard shortcuts, templates, and auto-cleanup.
Ask the AI
"What are the properties?" "Is this drug-like?" "How would I synthesize this?"
Get answers instantly
Properties, reactions, retrosynthesis routes, IUPAC names — computed and AI-assisted.
Chemical Structure Editor Features for Drug Discovery
Professional structure drawing meets conversational AI. No downloads, no plugins — just open your browser.
AI Chat Alongside Your Canvas
Ask the AI about your molecule and get instant answers. The AI always knows what’s on your canvas — no copy-pasting molecular representations into separate AI tools.
Property Prediction
Molecular weight, logP, H-bond donors/acceptors, TPSA, and Lipinski Rule of Five — computed by RDKit with deterministic accuracy. AI suggestions clearly labeled.
Retrosynthesis Suggestions
Draw your target molecule and ask for synthetic routes. Get multi-step retrosynthetic analysis with starting materials and reagents.
Also includes
Professional Structure Drawing
Draw with Ketcher — bonds, atoms, rings, templates, and keyboard shortcuts.
Natural Language to Structure
Type "draw ibuprofen" and it appears on your canvas.
Reaction Prediction & Schemes
Draw reactants, describe reagents, and see predicted products. Toggle reaction mode for multi-step scheme drawing with reaction arrows and RXN export.
IUPAC Naming
Convert between structures and systematic names in either direction.
Import & Export
7+ formats including CDXML (ChemDraw), SDF, and InChI. Publication-quality PNG and SVG with ACS presets.
Cloud Save
Auto-save, document management, accessible from any browser.
Structure OCR
Upload an image of a chemical structure — from a paper, patent, or slide — and extract the molecule onto your canvas. RDKit-validated before loading.
PubChem Search
Look up compounds by name, CAS number, or formula. Browse similar structures with Tanimoto similarity scoring. Load any result directly to your canvas.
Batch Property Analysis
Import a multi-molecule SDF and compute properties for every structure. Sort by any column, flag Lipinski violations, and export enriched SDF files.
Built for accuracy, not hype
Property predictions are computed by RDKit — the same open-source cheminformatics toolkit trusted by pharma companies worldwide.
When we show you a number, we tell you where it came from.
MW, logP, HBD, HBA, TPSA — deterministic results from the same toolkit used by pharma companies worldwide.
Reactions, retrosynthesis, complex properties — clearly labeled with confidence indicators.
Valence errors and geometry checks before AI analysis — catches mistakes early.
Why Switch from ChemDraw to ChemStitch
Keyboard-first drawing
Speed through structure drawing with keyboard shortcuts. Single, double, triple bonds with 1/2/3. Ring templates with R. Full undo/redo. Tab to switch between canvas and chat.
Your data, your keys
Bring your own OpenAI or Anthropic API key — or use the platform default during your trial. Your structures are saved to your private cloud account. Nothing is shared without your permission.
How ChemStitch compares
ChemDraw discontinued perpetual licenses in January 2025. ACD/ChemSketch was sunset in January 2026 after Revvity acquired ACD/Labs. If you’re looking for a modern alternative with AI built in, ChemStitch was built for you.
| ChemStitch | ChemDraw | ChemDoodle | Ketcher | |
|---|---|---|---|---|
| Price (individual/yr) | Free trial | $300–2,000+ | $350 | Free |
| AI chat & analysis | ||||
| Property prediction | ||||
| Retrosynthesis | ||||
| Web-native | ||||
| IUPAC naming | ||||
| Structure OCR from images | ||||
| PubChem integration | ||||
| Batch property analysis | ||||
| Publication export presets |
What ChemStitch doesn’t do (yet)
We believe in telling you what a tool can’t do, not just what it can. ChemStitch is in active development.
- Desktop browsers only — mobile and tablet support coming later
- Single-user workspace — real-time collaboration is on our roadmap
- No 3D structure visualization — 2D drawing and analysis only
- AI predictions are suggestions — always verify experimentally
- No ELN integration yet — standalone tool
Have a feature request? Email us
Frequently asked questions
Is there a free alternative to ChemDraw?
Yes. ChemStitch is a free, browser-based chemical structure editor with AI-powered property prediction, retrosynthesis, and IUPAC naming. It imports CDXML (ChemDraw’s native format), SMILES, MOL, SDF, InChI, and RXN — no install or license required.
What is the best free chemical structure editor?
ChemStitch combines a full-featured structure drawing canvas with conversational AI. Draw molecules, get RDKit-computed properties (MW, logP, HBD, HBA, TPSA, Lipinski), predict reactions, and export publication-quality SVG and PNG — all free in your browser.
Can I draw molecules online without installing software?
Yes. ChemStitch runs entirely in the browser. Draw structures with standard bond types, ring templates, and functional group libraries. Export as MOL V2000/V3000, SDF, SVG, or PNG at up to 600 DPI with ACS publication presets.
What tools can I use for retrosynthesis planning?
ChemStitch includes AI-suggested retrosynthesis routes. Draw your target molecule and ask the AI for synthetic routes — it proposes multi-step pathways with reagents and conditions. Predictions are clearly labeled as AI-suggested so you know to verify experimentally.
Is ChemStitch free?
ChemStitch starts with a 14-day free trial — no credit card required. We’re building it for individual researchers, not enterprise budgets. We’ll announce subscription pricing before your trial ends and give existing users plenty of notice.
Can I import ChemDraw files?
Yes. ChemStitch imports CDXML files (ChemDraw’s native format), plus SMILES, MOL V2000/V3000, SDF, InChI, and RXN. ChemDraw-specific features like enhanced stereochemistry labels may display differently.
How accurate are the AI predictions?
Property calculations (MW, logP, HBD, HBA, TPSA, Lipinski) are computed by RDKit — deterministic and reproducible. Reaction predictions and retrosynthesis are AI-suggested and clearly labeled. We always tell you where a number came from.
What happens to my data?
Your structures are saved to your private cloud account with encryption at rest. If you use your own API key, it’s encrypted with AES-256-GCM. We never share your chemical structures.
Does it work offline?
Not currently. ChemStitch is a web application that requires an internet connection for AI features and cloud save. The structure editor itself could work offline in the future, but AI features will always need connectivity.
Start your free trial
Try ChemStitch free for 14 days. No credit card required — sign up and start drawing molecules with AI in minutes.
No credit card required. Free for 14 days — we’ll email you a sign-in link.
ChemStitch will be priced for individual researchers, not enterprise budgets. Try free for 14 days — we’ll announce subscription pricing before your trial ends.