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ErezDraw
A prototype desktop and self-hosted web editor for drawing chemical structures, reactions, and figures.
Open source. 42 of 65 checklist features confirmed.
Main canvas
Dark mode changes surrounding interface; drawing canvas stays white.
Default drawings
Caffeine
Paclitaxel
No 3D view
Cholesterol in 3D
- Default canvas is white; labels use Arial 10 pt.
- SMILES caffeine gains three positive nitrogen charges.
- Caffeine MOL export fails RDKit aromatic sanitization.
- Paclitaxel retains all 11 fixture stereocenters.
- Default PNG is 276×243 pixels without DPI metadata.
Facts
- GitHub stars
- 5 stars on 6 Nov 2026
- First commit
- 12 Oct 2026
- Repository activity
- 25 commits, 1 contributor, last push 29 Oct 2026
- Latest version
- windows-2026-10-15-template-picker
- Version we tested
- 178f2b5
- Runs on
- Browser
- License
- GNU GPL version 3 or later.
- Price
- Free
- Relies on
- RDKit, ChemCanvas, nmr-predictor, OpenChemLib. Custom SVG editor; geometry partly adapted from ChemCanvas; RDKit and OpenChemLib support chemistry.
- Draws with
- Custom JavaScript/SVG
- Chemistry from
- RDKit
- Interface
- PySide6/Qt desktop shells; HTML/CSS/JavaScript web interface
- Main language
- JavaScript
- Other languages
- Python: Chemistry, import, desktop and server backends; C++: Native RDKit chemistry
- Renderer
- Original: ErezDraw SVG; ported ChemCanvas geometry
- Third-party licenses
- Includes GPL-3.0-or-later (ChemCanvas), LGPL-3.0 (PySide6/Qt), and GPL-2.0-or-later with PyInstaller exception; NMRShiftDB2 data has ODbL-derived share-alike terms requiring OSI-approved dependent software.
- Download
- 21 MB
- Installed
- 661 MB
- Development checkpoint with conflicting historical documentation; no feature-complete release is claimed.
- ChemDraw imports are lossy; ChemDraw export and editable Office round trips are unavailable.
- Organometallic checks and NMR predictions have explicit coverage limits.
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 wedge, hashed wedge and wavy bonds on the canvas.
Ring tools
Six-membered ring and aromatic rings on the canvas.
Template library
Triphenylphosphine drawing on the canvas.
Reaction arrows
Forward and equilibrium arrows on the canvas.
Curved mechanism arrows
Selected curved fishhook arrow on the canvas.
Formula and mass
Molecular analysis shows caffeine’s formula and molecular weight.
Structure to name
Caffeine structure with its systematic name beneath it.
PDF export
Printed page includes the editor toolbar and caffeine drawing.
High-resolution PNG
Exported PNG of the caffeine drawing.
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 and triple bonds by hand. Opens the screenshot.Single, double and triple bondsDrew single, double and triple bonds by hand.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
- Partly: Coordination bonds only; no hydrogen-bond or quadruple-bond tool. Opens the cited page.Dative, hydrogen and quadruple bondsCoordination bonds only; no hydrogen-bond or quadruple-bond tool.github.com
- Yes, according to the manual: Clicking a double bond cycles left, right and center. Opens the cited page.Choose double-bond sideClicking a double bond cycles left, right and center.github.com
- Yes, tested by running it: Placed a six-membered ring; aromatic ring tool also visible. Opens the screenshot.Ring toolsPlaced a six-membered ring; aromatic ring tool also visible.github.com
- Yes, according to the manual: Includes two cyclohexane chair templates. Opens the cited page.Chair and Haworth ringsIncludes two cyclohexane chair templates.github.com
- Yes, according to the manual: Dragging determines zigzag chain length. Opens the cited page.Chain toolDragging determines zigzag chain length.github.com
- Yes, tested by running it: Placed the triphenylphosphine ligand template. Opens the screenshot.Template libraryPlaced the triphenylphosphine ligand template.github.com
- No: No general user template library. Opens the cited page.Save your own templatesNo general user template library.github.com
- Yes, according to the manual: Limited aliases, including Ph and OMe, are chemically interpreted. Opens the cited page.Group abbreviationsLimited aliases, including Ph and OMe, are chemically interpreted.github.com
- Partly: Arbitrary labels and formal charges; no editable isotope field. Opens the cited page.Charges, isotopes and atom labelsArbitrary labels and formal charges; no editable isotope field.github.com
- Yes, according to the manual: Radical and lone-pair placement on atoms persists in drawings. Opens the cited page.Radicals and lone pairsRadical and lone-pair placement on atoms persists in drawings.github.com
- Yes, according to the manual: Hover shortcuts change atom labels, bond orders and styles. Opens the cited page.Keyboard drawingHover shortcuts change atom labels, bond orders and styles.github.com
- Yes, according to the manual: Lasso selection, rotation, resizing and horizontal/vertical flips. Opens the cited page.Lasso select and transformsLasso selection, rotation, resizing and horizontal/vertical flips.github.com
- Yes, according to the manual: X/Y trackball tilts structures; depth persists in native drawings. Opens the cited page.Tilt drawings in perspectiveX/Y trackball tilts structures; depth persists in native drawings.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 and moved a curved half-head arrow. Opens the screenshot.Curved mechanism arrowsDrew and moved a curved half-head arrow.github.com
- Not establishedMachine-readable reactions
- No: No atom-to-atom reaction mapping. Opens the cited page.Atom mappingNo atom-to-atom reaction mapping.github.com
- Yes, according to the manual: Graphical s, p, dxy, dz2 and hybrid orbitals. Opens the cited page.Orbitals and symbolsGraphical s, p, dxy, dz2 and hybrid orbitals.github.com
Figures and layout
- Yes, according to the manual: Captions support fonts, substring formatting, subscripts and superscripts. Opens the cited page.Rich text captionsCaptions support fonts, substring formatting, subscripts and superscripts.github.com
- Yes, according to the manual: Editable rectangles, ellipses, brackets and Bézier curves. Opens the cited page.Shapes, brackets and curvesEditable rectangles, ellipses, brackets and Bézier curves.github.com
- Yes, according to the manual: Six alignment modes and horizontal/vertical equal-gap distribution. Opens the cited page.Align and distributeSix alignment modes and horizontal/vertical equal-gap distribution.github.com
- Yes, according to the manual: Persistent Group, Ungroup and integral grouping commands. Opens the cited page.Group and ungroupPersistent Group, Ungroup and integral grouping commands.github.com
- Yes, according to the manual: RDKit 2D cleanup protects metal, coordination and wedge/hash components. Opens the cited page.2D structure cleanupRDKit 2D cleanup protects metal, coordination and wedge/hash components.github.com
- Yes, according to the manual: Built-in ACS Document 1996 preset. Opens the cited page.Journal drawing stylesBuilt-in ACS Document 1996 preset.github.com
- Yes, according to the manual: Custom bond and font settings persist in reusable drawing files. Opens the cited page.Reusable custom stylesCustom bond and font settings persist in reusable drawing files.github.com
- Yes, according to the manual: Atom labels and captions can be colored individually. Opens the cited page.Color controlAtom labels and captions can be colored individually.github.com
- Partly: Hover backgrounds and halos are temporary and excluded from SVG/PNG exports. Opens the cited page.Color highlightingHover backgrounds and halos are temporary and excluded from SVG/PNG exports.github.com
- Partly: Editable page dimensions and margins; no multipage layout. Opens the cited page.Page layout and multipageEditable page dimensions and margins; no multipage layout.github.com
- Not establishedImported pictures
- Yes, according to the manual: Editable tables; dedicated TLC tool was removed. Opens the cited page.TLC plates and tablesEditable tables; dedicated TLC tool was removed.github.com
Chemistry intelligence
- Yes, according to the manual: Manual RDKit checks; metal and unsupported-label coverage is incomplete. Opens the cited page.Structure checkingManual RDKit checks; metal and unsupported-label coverage is incomplete.github.com
- No: No R/S or E/Z assignment. Opens the cited page.R/S and E/Z labelsNo R/S or E/Z assignment.github.com
- Yes, tested by running it: MOL caffeine: C8H10N4O2, molecular weight 194.194. Opens the screenshot.Formula and massMOL caffeine: C8H10N4O2, molecular weight 194.194.github.com
- Yes, according to the manual: Offline RDKit logP and TPSA estimates for organic molecules. Opens the cited page.Property estimatesOffline RDKit logP and TPSA estimates for organic molecules.github.com
- Yes, tested by running it: Caffeine loaded using PubChem; absent from local dictionary. Opens the cited page.Name to structureCaffeine loaded using PubChem; absent from local dictionary.github.com
- Yes, tested by running it: PubChem returned 1,3,7-trimethylpurine-2,6-dione for MOL caffeine. Opens the screenshot.Structure to namePubChem returned 1,3,7-trimethylpurine-2,6-dione for MOL caffeine.github.com
- Yes, according to the manual: Local 1H/13C shifts; limited coverage and approximate proton environments. Opens the cited page.NMR predictionLocal 1H/13C shifts; limited coverage and approximate proton environments.github.com
- No: No query atoms, alternative groups or generic matching rules. Opens the cited page.R-groups and query structuresNo query atoms, alternative groups or generic matching rules.github.com
- No: No repeat-unit model. Opens the cited page.Polymers and repeat unitsNo repeat-unit model.github.com
- Not establishedPeptides and nucleic acids
- Not establishedImage to structure
- Yes, tested by running it: PubChem successfully resolved caffeine name and structure. Opens the cited page.Online structure lookupPubChem successfully resolved caffeine name and structure.github.com
- No: SDF opens flat; perspective edits drawings without a model viewer. Opens the cited page.3D model viewSDF opens flat; perspective edits drawings without a model viewer.github.com
- Not establishedCrystal structures
Files and exchange
- Partly: Imported three-atom CDXML; no CDXML export command. Opens the cited page.CDXML import and exportImported three-atom CDXML; no CDXML export command.github.com
- Partly: Imports supported objects; no CDX export or lossless round trip. Opens the cited page.CDX import and exportImports supported objects; no CDX export or lossless round trip.github.com
- Yes, tested by running it: Imported MOL and SDF; exported MOL. Opens the cited page.MOL and SDFImported MOL and SDF; exported MOL.github.com
- Partly: Paclitaxel imports correctly; caffeine becomes +3. No SMILES export. Opens the cited page.SMILESPaclitaxel imports correctly; caffeine becomes +3. No SMILES export.github.com
- Not establishedInChI
- Not establishedRXN files
- Yes, tested by running it: Default SVG files saved for both 2D fixtures. Opens the cited page.SVG exportDefault SVG files saved for both 2D fixtures.github.com
- Partly: Print PDF rasterizes the entire editor, including toolbars. Opens the screenshot.PDF exportPrint PDF rasterizes the entire editor, including toolbars.
- Partly: Default output is 276×243 pixels, without DPI metadata. Opens the screenshot.High-resolution PNGDefault output is 276×243 pixels, without DPI metadata.github.com
- No: No proprietary ChemDraw clipboard data. Opens the cited page.Paste to and from ChemDrawNo proprietary ChemDraw clipboard data.github.com
- No: Word receives graphics; no ChemDraw OLE editing. Opens the cited page.Editable in Word or PowerPointWord receives graphics; no ChemDraw OLE editing.github.com
- Not establishedWindows Office OLE
APIs and automation
- Not establishedPython API
- Not establishedJavaScript or TypeScript API
- Not establishedCommand-line tool
- Not establishedAI agent control
- Not establishedBuilt-in AI assistant
Embedding and extension
- Not establishedPlugins
- Not established: Self-hosted web editor; no supported editor embedding interface confirmed.Embed in your own appSelf-hosted web editor; no supported editor embedding interface confirmed.github.com