Check your mechanism
Athanor pushes your curved arrows and tells you, step by step, whether they give what you drew next. A wrong step says what went wrong, not only that it is wrong.
Organic chemistry you can see moving.
Draw a mechanism and watch the electrons flow. Check your arrows, turn molecules in 3D and practice until it clicks. Free.
Windows 10 and 11 Updates itself from the Store
Open in browser
Runs in your browser. No account needed to draw.
The molecule you drew, in 3D with its p orbitals. Drag to turn it.
Mechanisms that animate themselves
Draw a mechanism the way you would on paper, press play, and Athanor animates it: bonds form and break where your arrows say they do. If an arrow is wrong, you find out before the exam does.
What it does for your course
Write it with a pen
On a tablet or with a stylus, draw structures by hand and Athanor turns your strokes into clean ones on the device.
Flashcards and practice
Study reactions as flashcards, play practice games, and work through practice sets that bring back what you missed.
Join your class
Your instructor gives you a code or a link. Open it, answer in the browser, and your work goes to their gradebook.
Plans and pricing
Every plan has the whole editor, ChemDraw files, mechanisms, 3D, problem sets with grading, collaboration and commercial use. Product prediction and routes need only a free account and never use credits.
The paid plans are one arbastro Suite subscription for every arbastro app.
- AI credits a month
- 150
- Assistant models
- Haiku and Sonnet 5.5
- Your own AI provider key
- –
- Cloud storage
- 10 MB
arbastro Suite Lite
For learning and teaching
$4.17/mo
billed $49.99 yearly · save $9.89
Start 7-day free trial
Then $4.17/mo billed yearly ($49.99), or $4.99 monthly. Cancel any time before the trial ends.
- AI credits a month
- 300
- Assistant models
- Haiku, Sonnet and Opus 5.5
- Your own AI provider key
- Cloud storage
- 100 MB
Most popular
arbastro Suite Plus
Best for active research
$16.67/mo
billed $199.99 yearly · save $39.89
- AI credits a month
- 1,000
- Assistant models
- Haiku, Sonnet and Opus 5.5, Fable 5.2
- Your own AI provider key
- Cloud storage
- 500 MB
arbastro Suite Ultra
For schools, labs and companies
$83.33/mo
billed $999.99 yearly · save $199.89
- AI credits a month
- 2,500
- Assistant models
- Haiku, Sonnet and Opus 5.5, Fable 5.2
- Your own AI provider key
- Cloud storage
- 3 GB
How Athanor compares
Swipe the table to see every tool
 Athanor | ChemDraw | ChemDoodle | Marvin | Octet Draw | Discontinued Aug 2026ChemSketch | |
|---|---|---|---|---|---|---|
| Price & access | ||||||
| Price | Free | Prime $700/yrProfessional $1,355/yr | $199/yror $999 lifetime | $29/mo academic$99/mo commercial | Free | No longer sold |
| Free for commercial work | – | – | – | – | ||
| Full editor in the browser | Enterprise plan | Developer toolkit | – | – | ||
| Prediction | ||||||
| Products predicted as you draw | – | From arrow pushing | – | – | – | |
| Retrosynthesis route planning | – | Manual disconnections | – | – | – | |
| Property prediction | Basic | |||||
| AI assistant that draws and animates | – | – | – | – | – | |
| Teaching | ||||||
| Problem sets with automatic grading | 21 question types | – | – | – | – | – |
| Mechanism checking | – | – | – | – | – | |
| Moodle XML and QTI export | – | – | – | – | – | |
| Drawing & visualization | ||||||
| 2D structure drawing | ||||||
| 3D models | – | |||||
| Orbitals and MO diagrams | Orbital palette | – | – | – | ||
| Animated mechanisms | – | – | – | – | – | |
| Biopolymers (HELM, peptides, DNA) | – | – | – | – | ||
| Data & workflow | ||||||
| Compound library with cited safety data | PubChem add‑in | – | – | – | – | |
| Live collaboration | In testing | Enterprise plan | – | – | – | – |
| Opens ChemDraw files | ||||||
| Name to structure for any IUPAC name | Online | Offline | – | |||
| Platforms | ||||||
| Desktop app | Windows | Windows, Mac | Windows, Mac, Linux | Windows, Mac, Linux | Windows | |
| Mac and Linux | In the browser | Mac | – | |||
| Works offline | Desktop app | Desktop | ||||
| Open source | – | – | – | – | Apache‑2.0 | – |
| Where others do more | ||||||
| ¹H and ¹³C NMR prediction | Predicted, AI | – | ||||
| Fully offline, no account | – | – | ||||
| Office and ELN integration | – | LabArchives | Office, on Mac | – |
Prices as of October 2026, from each vendor’s own page. Check with the vendor before you buy.
Athanor in your AI assistant
Claude, ChatGPT, Cursor and other assistants can use Athanor’s own chemistry engine through MCP: convert, name, draw and check structures, and run the safety screen. Free, with no account, and nothing stored.
The server
https://mcp-athanor.arbastro.com/mcpconvertSMILES, MOL and XYZnameIUPAC and common namespropertiesformula, masses, descriptorsdepictjournal-style drawingscheckvalence, charge, stereoscreenthe safety screenlibrary_searchAthanor’s library
In Claude Code, one line
claude mcp add --transport http athanor https://mcp-athanor.arbastro.com/mcp
A real call: name on ibuprofen’s SMILES
Asking the server…
Your data
How we handle your workLocal first, synced to your account
Screened for misuse
An open file format
FAQ
Get Athanor
Free on Windows and in your browser, on a laptop or a tablet.
Windows app
Windows 10 and 11. Works offline after you sign in.
Updates itself from the Store. The installer is under the arrow.
In your browser
Chrome, Edge, Firefox or Safari.
Open in browserNothing to install.