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Octet Draw
Free desktop software for drawing chemical structures, reaction schemes and publication figures.
Open source. 55 of 65 checklist features confirmed.
Official demo
Main canvas
Settings > Document > Page > Background: White or Dark.
Default drawings
Caffeine
Paclitaxel
Cholesterol in 3D
- Defaults: ACS Document 1996, Arial 10 pt, black on white.
- Caffeine aromatic rings display only single-line ring bonds.
- Paclitaxel automatic layout has overlapping central oxygen labels.
- Caffeine and paclitaxel MOL exports match fixture connectivity and stereochemistry.
- Cholesterol 3D labels overlap; exported coordinates invert three stereocenters.
- Redraw: current Kekule SMILES displays caffeine and paclitaxel alternating ring double bonds.
- Redraw: fresh cholesterol 3D export preserves all eight stereocenters; supersedes earlier inversion observation.
Facts
- GitHub stars
- 78 stars on 6 Nov 2026
- First commit
- 14 Oct 2026
- Repository activity
- 781 commits, 2 contributors, last push 4 Nov 2026
- Latest version
- v1.1.0
- Version we tested
- 1.1.0
- Runs on
- macOS, Windows, Linux
- License
- Apache License 2.0; bundled NMR data has separate share-alike terms.
- Price
- Free
- Relies on
- Indigo, OPSIN, InChI. Custom SVG canvas; Indigo chemistry, OPSIN name conversion, and bundled InChI.
- Draws with
- Custom TypeScript SVG renderer; svg2pdf for PDF and resvg/tiny-skia for raster export
- Chemistry from
- Indigo WebAssembly, OPSIN, and in-house naming, stereochemistry and property calculations
- Interface
- React and TypeScript in Tauri 2
- Main language
- TypeScript
- Other languages
- Rust: Native shell, export and clipboard; JavaScript: OPSIN bundle and WebAssembly glue; C++: Indigo chemistry compiled to WebAssembly; C: InChI compiled into Indigo WebAssembly
- Renderer
- Original: Octet ACS 1996 SVG renderer
- Third-party licenses
- Includes MPL-2.0 crates, custom LGPL-2.1-based InChI, OFL-1.1 fonts, ODbL-derived share-alike NMR data (dependent software must be OSI-licensed), and proprietary WebView2 (Windows offline installer).
- Download
- 33 MB
- Installed
- 44 MB
- Office round-trip editing depends on preserving embedded PDF or EMF chemistry metadata.
- SMILES layout is capped at 1,000 atoms; 3D cleanup at 500.
- Older notes predate implemented NMR, properties, queries, peptides, dictionaries, Windows EMF and PubChem fetching.
In use
Screenshots from our test of this version.
Single, double and triple bonds
Single, double and triple bonds on the drawing canvas.
Wedge, hash and wavy bonds
Solid and hashed wedge bonds on the drawing canvas.
Ring tools
A benzene ring on the drawing canvas.
Tilt drawings in perspective
Depth-shaded cholesterol drawing with overlapping atom labels.
Reaction arrows
A forward reaction arrow on the drawing canvas.
Curved mechanism arrows
Curved arrows on the drawing canvas.
2D structure cleanup
Clean up structure command beside a selected molecule.
Color control
Colour controls beside a selected molecule.
Formula and mass
Caffeine formula, exact mass and molecular weight in Properties.
Property estimates
Caffeine properties include logP and tPSA estimates.
Structure to name
Caffeine structure and systematic name on the canvas.
3D model view
Depth-shaded cholesterol drawing with overlapping atom labels.
MOL and SDF
Export dialog with MOL selected as the format.
High-resolution PNG
PNG export dialog showing 600 dpi and transparent background.
Features
- Tested by running it
- Seen in the app
- The manual says yes
- Partly, with the reason shown
- Not supported
- Not established, which is not the same as no
Select a mark for its proof. A filled mark opens our screenshot, or the manual if the check left nothing to picture. A ring opens the manual.
Drawing structures
- Yes, tested by running it: Drew single, double, triple; changed an existing bond to double. Opens the screenshot.Single, double and triple bondsDrew single, double, triple; changed an existing bond to double.github.com
- Yes, tested by running it: Drew solid wedge, hashed wedge and wavy bonds. Opens the screenshot.Wedge, hash and wavy bondsDrew solid wedge, hashed wedge and wavy bonds.github.com
- Yes, according to the manual: Dative, hydrogen and quadruple bond tools. Opens the cited page.Dative, hydrogen and quadruple bondsDative, hydrogen and quadruple bond tools.github.com
- Yes, according to the manual: Double bonds offer left, right, centered and automatic positions. Opens the cited page.Choose double-bond sideDouble bonds offer left, right, centered and automatic positions.github.com
- Yes, tested by running it: Placed benzene and cyclohexane using ring tools. Opens the screenshot.Ring toolsPlaced benzene and cyclohexane using ring tools.github.com
- Yes, according to the manual: Chair, Haworth, Newman and other conformer templates. Opens the cited page.Chair and Haworth ringsChair, Haworth, Newman and other conformer templates.github.com
- Yes, according to the manual: Drag a zig-zag chain; atom count follows its length. Opens the cited page.Chain toolDrag a zig-zag chain; atom count follows its length.github.com
- Yes, tested by running it: Inserted the built-in alanine template. Opens the cited page.Template libraryInserted the built-in alanine template.github.com
- Yes, according to the manual: Save selected drawings into reusable named template sets. Opens the cited page.Save your own templatesSave selected drawings into reusable named template sets.github.com
- Yes, according to the manual: Ph, Boc and condensed labels resolve into chemical structures. Opens the cited page.Group abbreviationsPh, Boc and condensed labels resolve into chemical structures.github.com
- Yes, according to the manual: Atom Properties sets element labels, charges and isotope mass numbers. Opens the cited page.Charges, isotopes and atom labelsAtom Properties sets element labels, charges and isotope mass numbers.github.com
- Yes, according to the manual: Atom symbol tools place radical dots and lone pairs. Opens the cited page.Radicals and lone pairsAtom symbol tools place radical dots and lone pairs.github.com
- Yes, according to the manual: Point at an atom or bond and use chemistry shortcut keys. Opens the cited page.Keyboard drawingPoint at an atom or bond and use chemistry shortcut keys.github.com
- Yes, according to the manual: Lasso selection supports rotation, flipping and resizing. Opens the cited page.Lasso select and transformsLasso selection supports rotation, flipping and resizing.github.com
- Yes, tested by running it: Generated depth-shaded cholesterol and rotated it by dragging. Opens the screenshot.Tilt drawings in perspectiveGenerated depth-shaded cholesterol and rotated it by dragging.github.com
Reactions and mechanisms
- Yes, tested by running it: Drew forward and equilibrium arrows. Opens the screenshot.Reaction arrowsDrew forward and equilibrium arrows.github.com
- Yes, tested by running it: Drew curved electron-pair and fishhook arrows. Opens the screenshot.Curved mechanism arrowsDrew curved electron-pair and fishhook arrows.github.com
- Yes, according to the manual: Chemistry-aware reactions export RXN, RDF and reaction SMILES. Opens the cited page.Machine-readable reactionsChemistry-aware reactions export RXN, RDF and reaction SMILES.github.com
- Yes, according to the manual: Automatic reaction mapping preserves manually mapped atom pairs. Opens the cited page.Atom mappingAutomatic reaction mapping preserves manually mapped atom pairs.github.com
- Yes, according to the manual: Orbital library includes s, p, hybrid and other shapes. Opens the cited page.Orbitals and symbolsOrbital library includes s, p, hybrid and other shapes.github.com
Figures and layout
- Yes, according to the manual: Canvas captions support fonts, subscripts, superscripts and styled text. Opens the cited page.Rich text captionsCanvas captions support fonts, subscripts, superscripts and styled text.github.com
- Yes, according to the manual: Editable shapes, brackets and Bézier curves. Opens the cited page.Shapes, brackets and curvesEditable shapes, brackets and Bézier curves.github.com
- Yes, according to the manual: Selected objects align by edges or centers and distribute evenly. Opens the cited page.Align and distributeSelected objects align by edges or centers and distribute evenly.github.com
- Yes, according to the manual: Grouped structures and graphics select and move together. Opens the cited page.Group and ungroupGrouped structures and graphics select and move together.github.com
- Yes, according to the manual: Clean Up straightens bond lengths and angles. Opens the cited page.2D structure cleanupClean Up straightens bond lengths and angles.github.com
- Yes, according to the manual: ACS default with additional journal presets. Opens the cited page.Journal drawing stylesACS default with additional journal presets.github.com
- Yes, according to the manual: Save named style templates containing bond and font settings. Opens the cited page.Reusable custom stylesSave named style templates containing bond and font settings.github.com
- Yes, according to the manual: Color individual atoms, bonds, captions and drawing objects. Opens the cited page.Color controlColor individual atoms, bonds, captions and drawing objects.github.com
- Yes, according to the manual: Persistent colored atom/bond halos and ring fills, with custom colors. Opens the cited page.Color highlightingPersistent colored atom/bond halos and ring fills, with custom colors.github.com
- Partly: Page size controls and tiled printing; canvas lacks separate document pages. Opens the cited page.Page layout and multipagePage size controls and tiled printing; canvas lacks separate document pages.github.com
- Yes, according to the manual: Place raster images as picture objects. Opens the cited page.Imported picturesPlace raster images as picture objects.github.com
- Yes, according to the manual: Dedicated TLC plates and editable tables. Opens the cited page.TLC plates and tablesDedicated TLC plates and editable tables.github.com
Chemistry intelligence
- Yes, according to the manual: Flags valence and other structure problems. Opens the cited page.Structure checkingFlags valence and other structure problems.github.com
- Yes, according to the manual: Computes R/S/r/s and E/Z with its own CIP labeller. Opens the cited page.R/S and E/Z labelsComputes R/S/r/s and E/Z with its own CIP labeller.github.com
- Yes, tested by running it: Caffeine: C8H10N4O2, 194.19 g/mol; exact mass 194.0804. Opens the screenshot.Formula and massCaffeine: C8H10N4O2, 194.19 g/mol; exact mass 194.0804.github.com
- Yes, tested by running it: Caffeine properties panel showed logP 0.06 and tPSA 61.82. Opens the screenshot.Property estimatesCaffeine properties panel showed logP 0.06 and tPSA 61.82.github.com
- Yes, tested by running it: Converted caffeine to a 14-atom structure. Opens the cited page.Name to structureConverted caffeine to a 14-atom structure.github.com
- Yes, tested by running it: Generated caffeine systematic name as canvas text. Opens the screenshot.Structure to nameGenerated caffeine systematic name as canvas text.github.com
- Yes, according to the manual: Predicts proton and carbon-13 shifts. Opens the cited page.NMR predictionPredicts proton and carbon-13 shifts.github.com
- Yes, according to the manual: Supports R-group definitions, atom lists and query properties. Opens the cited page.R-groups and query structuresSupports R-group definitions, atom lists and query properties.github.com
- Yes, according to the manual: Semantic repeat units contribute to molecular formulae and masses. Opens the cited page.Polymers and repeat unitsSemantic repeat units contribute to molecular formulae and masses.github.com
- Yes, according to the manual: Reads three-letter peptide sequences with D/L residues and terminal caps. Opens the cited page.Peptides and nucleic acidsReads three-letter peptide sequences with D/L residues and terminal caps.github.com
- Not establishedImage to structure
- Yes, according to the manual: Fetches PubChem structures when offline name conversion fails. Opens the cited page.Online structure lookupFetches PubChem structures when offline name conversion fails.github.com
- Partly: Builds and rotates; cholesterol export inverts three stereocenters. Opens the screenshot.3D model viewBuilds and rotates; cholesterol export inverts three stereocenters.github.com
- Not establishedCrystal structures
Files and exchange
- Yes, tested by running it: Exported and re-imported structures, reaction arrow and mechanism arrows. Opens the cited page.CDXML import and exportExported and re-imported structures, reaction arrow and mechanism arrows.github.com
- Yes, according to the manual: Native CDX reader and writer preserve drawing objects. Opens the cited page.CDX import and exportNative CDX reader and writer preserve drawing objects.github.com
- Yes, tested by running it: Imported MOL and SDF; exported both formats. Opens the screenshot.MOL and SDFImported MOL and SDF; exported both formats.github.com
- Yes, tested by running it: Pasted all three fixtures; exported caffeine SMILES. Opens the cited page.SMILESPasted all three fixtures; exported caffeine SMILES.github.com
- Yes, according to the manual: Imports and exports InChI. Opens the cited page.InChIImports and exports InChI.github.com
- Yes, according to the manual: Reads and writes V2000 and V3000 RXN reactions. Opens the cited page.RXN filesReads and writes V2000 and V3000 RXN reactions.github.com
- Yes, tested by running it: Exported all three fixtures; SVG files parse successfully. Opens the cited page.SVG exportExported all three fixtures; SVG files parse successfully.github.com
- Yes, tested by running it: Exported caffeine using default PDF settings. Opens the cited page.PDF exportExported caffeine using default PDF settings.github.com
- Yes, tested by running it: Exported at default 600 dpi with transparent background. Opens the screenshot.High-resolution PNGExported at default 600 dpi with transparent background.github.com
- Yes, according to the manual: Reads and writes ChemDraw CDX and CDXML clipboard formats. Opens the cited page.Paste to and from ChemDrawReads and writes ChemDraw CDX and CDXML clipboard formats.github.com
- Yes, according to the manual: Round-trip editing via macOS PDF and Windows EMF clipboard metadata. Opens the cited page.Editable in Word or PowerPointRound-trip editing via macOS PDF and Windows EMF clipboard metadata.github.com
- No: Windows Office receives EMF pictures with CDXML metadata, not OLE objects. Opens the cited page.Windows Office OLEWindows Office receives EMF pictures with CDXML metadata, not OLE objects.github.com
APIs and automation
- Not establishedPython API
- Not establishedJavaScript or TypeScript API
- Not establishedCommand-line tool
- Not establishedAI agent control
- No: AI features explicitly remain outside current scope. Opens the cited page.Built-in AI assistantAI features explicitly remain outside current scope.raw.githubusercontent.com
Embedding and extension
- Not establishedPlugins
- Not established: Standalone desktop editor; no supported embedding integration found.Embed in your own appStandalone desktop editor; no supported embedding integration found.github.com