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Covalent
A free browser editor for chemical structures, reaction schemes, and multipage drawing documents.
Free. 35 of 65 checklist features confirmed.
Main canvas
Default drawings
Caffeine
Paclitaxel
Cholesterol in 3D
- The hosted build identifier appears in the served asset path.
- Default 2D canvas used a dark background and coloured heteroatoms.
- Paclitaxel was automatically fitted with wedge and hashed bonds.
- Cholesterol 3D default was ball-and-stick with hydrogens shown.
- The SDF import displayed explicit hydrogens in the drawing.
Facts
- Version we tested
- 2uu6kqoryy
- Runs on
- Browser, iOS, Android
- License
- Free browser service; no open-source license identified.
- Price
- Free
- Relies on
- Not established. Public vendor documentation does not establish canvas provenance or third-party chemistry libraries.
- Draws with
- Custom SVG for 2D and SVG export; Canvas 2D for PNG and 3D; custom vector PDF writer.
- Chemistry from
- Custom JavaScript chemistry core
- Interface
- Custom JavaScript DOM UI
- Main language
- JavaScript
- Other languages
- None
- Renderer
- Original: Covalent SVG molecular renderer
- Third-party licenses
- Includes Inter fonts under SIL OFL-1.1 with font share-alike terms; documents are exempt.
- ChemDraw CDXML import is available; binary CDX is unsupported.
- Office pasting turns structures and arrows into pictures.
- Offline operation is undocumented; the browser editor requires JavaScript.
In use
Screenshots from our test of this version.
Single, double and triple bonds
Bond tools and a Paclitaxel structure with single and double bonds.
Wedge, hash and wavy bonds
Wedge, hashed and wavy bond tools beside a Paclitaxel structure.
Ring tools
Ring tools and aromatic rings in a Paclitaxel structure.
Group abbreviations
Keyboard instructions mention OMe, Ph and Boc group labels.
Charges, isotopes and atom labels
Keyboard instructions for element labels and atom charges.
Keyboard drawing
Keyboard instructions for atom labels, charges and bond order.
2D structure cleanup
Clean up command above the caffeine drawing.
R/S and E/Z labels
Paclitaxel structure with R and S descriptors in the panel.
Formula and mass
Caffeine structure with molecular formula and molar mass.
Structure to name
Caffeine structure and its name in the structure panel.
3D model view
Cholesterol ball-and-stick model with 3D display controls.
High-resolution PNG
Exported PNG page showing a caffeine structure.
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. Opens the screenshot.Single, double and triple bondsDrew single, double and triple bonds.chempirical.com
- Yes, tested by running it: Drew wedge and hash; changed selected bond to wavy. Opens the screenshot.Wedge, hash and wavy bondsDrew wedge and hash; changed selected bond to wavy.chempirical.com
- Not establishedDative, hydrogen and quadruple bonds
- Not establishedChoose double-bond side
- Yes, tested by running it: Drew benzene and a six-membered ring. Opens the screenshot.Ring toolsDrew benzene and a six-membered ring.chempirical.com
- Not establishedChair and Haworth rings
- Yes, according to the manual: Drag length controls a carbon chain with 120-degree zigzags. Opens the cited page.Chain toolDrag length controls a carbon chain with 120-degree zigzags.chempirical.com
- Partly: Worksheet template adds several editable structures, not individual structure templates. Opens the cited page.Template libraryWorksheet template adds several editable structures, not individual structure templates.chempirical.com
- Not establishedSave your own templates
- Yes, according to the manual: Groups such as Ph, OMe and Boc expand into atoms. Opens the cited page.Group abbreviationsGroups such as Ph, OMe and Boc expand into atoms.chempirical.com
- Partly: Charges and elements editable; direct isotope editing unverified. Opens the cited page.Charges, isotopes and atom labelsCharges and elements editable; direct isotope editing unverified.chempirical.com
- Not establishedRadicals and lone pairs
- Yes, according to the manual: Element hotkeys and 1/2/3 change atoms and bonds under pointer. Opens the cited page.Keyboard drawingElement hotkeys and 1/2/3 change atoms and bonds under pointer.chempirical.com
- Partly: Rectangular selection, rotation and flipping; drawings resize in Page view. Opens the cited page.Lasso select and transformsRectangular selection, rotation and flipping; drawings resize in Page view.chempirical.com
- Not establishedTilt drawings in perspective
Reactions and mechanisms
- Yes, tested by running it: Drew forward arrow and changed another to equilibrium. Opens the cited page.Reaction arrowsDrew forward arrow and changed another to equilibrium.chempirical.com
- Yes, tested by running it: Converted page arrow to curved electron-pair arrow. Opens the cited page.Curved mechanism arrowsConverted page arrow to curved electron-pair arrow.chempirical.com
- Yes, according to the manual: Reaction SMILES and RXN preserve reactants and products. Opens the cited page.Machine-readable reactionsReaction SMILES and RXN preserve reactants and products.chempirical.com
- Not establishedAtom mapping
- Not establishedOrbitals and symbols
Figures and layout
- Partly: Subscripts, superscripts and font sizing; typeface is fixed. Opens the cited page.Rich text captionsSubscripts, superscripts and font sizing; typeface is fixed.chempirical.com
- Yes, according to the manual: Page tools include boxes, ellipses and brackets. Opens the cited page.Shapes, brackets and curvesPage tools include boxes, ellipses and brackets.chempirical.com
- Yes, according to the manual: Align objects or distribute them horizontally and vertically. Opens the cited page.Align and distributeAlign objects or distribute them horizontally and vertically.chempirical.com
- Yes, according to the manual: Group and ungroup page objects. Opens the cited page.Group and ungroupGroup and ungroup page objects.chempirical.com
- Yes, according to the manual: Clean up command: Ctrl+L. Opens the cited page.2D structure cleanupClean up command: Ctrl+L.chempirical.com
- Yes, according to the manual: ACS Document 1996 preset. Opens the cited page.Journal drawing stylesACS Document 1996 preset.chempirical.com
- Not establishedReusable custom styles
- Yes, according to the manual: Text, arrows and shapes have individual colour controls. Opens the cited page.Color controlText, arrows and shapes have individual colour controls.chempirical.com
- Partly: Atom and bond selection halos are excluded from exports. Opens the cited page.Color highlightingAtom and bond selection halos are excluded from exports.chempirical.com
- Yes, tested by running it: Worksheet template added a second page; page-size control visible. Opens the cited page.Page layout and multipageWorksheet template added a second page; page-size control visible.chempirical.com
- Not establishedImported pictures
- Not establishedTLC plates and tables
Chemistry intelligence
- Yes, according to the manual: Valence problems are displayed in the Check section. Opens the cited page.Structure checkingValence problems are displayed in the Check section.chempirical.com
- Yes, tested by running it: Paclitaxel panel displayed R/S descriptors. Opens the screenshot.R/S and E/Z labelsPaclitaxel panel displayed R/S descriptors.chempirical.com
- Yes, tested by running it: Caffeine displayed C8H10N4O2 and 194.19 g/mol. Opens the screenshot.Formula and massCaffeine displayed C8H10N4O2 and 194.19 g/mol.chempirical.com
- Not establishedProperty estimates
- Yes, tested by running it: Aspirin search inserted its structure. Opens the cited page.Name to structureAspirin search inserted its structure.chempirical.com
- Partly: Identified caffeine; systematic name generation was not demonstrated. Opens the screenshot.Structure to nameIdentified caffeine; systematic name generation was not demonstrated.chempirical.com
- No: Provided by a separate Chempirical NMR predictor. Opens the cited page.NMR predictionProvided by a separate Chempirical NMR predictor.chempirical.com
- Not establishedR-groups and query structures
- Not establishedPolymers and repeat units
- Not establishedPeptides and nucleic acids
- Not establishedImage to structure
- Yes, tested by running it: Search returned and inserted aspirin. Opens the cited page.Online structure lookupSearch returned and inserted aspirin.chempirical.com
- Yes, tested by running it: Generated cholesterol ball-and-stick model and rotated it. Opens the screenshot.3D model viewGenerated cholesterol ball-and-stick model and rotated it.chempirical.com
- Not establishedCrystal structures
Files and exchange
- Partly: Imported a two-atom CDXML; no CDXML export shown. Opens the cited page.CDXML import and exportImported a two-atom CDXML; no CDXML export shown.chempirical.com
- No: Official comparison explicitly says CDX is not yet supported. Opens the cited page.CDX import and exportOfficial comparison explicitly says CDX is not yet supported.chempirical.com
- Yes, tested by running it: Imported MOL and SDF; exported V3000 MOL. Opens the cited page.MOL and SDFImported MOL and SDF; exported V3000 MOL.chempirical.com
- Yes, tested by running it: Pasted fixtures and copied caffeine SMILES. Opens the cited page.SMILESPasted fixtures and copied caffeine SMILES.chempirical.com
- Not establishedInChI
- Yes, according to the manual: Open and export RXN reaction files. Opens the cited page.RXN filesOpen and export RXN reaction files.chempirical.com
- Yes, tested by running it: Downloaded structure SVGs. Opens the cited page.SVG exportDownloaded structure SVGs.chempirical.com
- Yes, tested by running it: Downloaded a one-page PDF. Opens the cited page.PDF exportDownloaded a one-page PDF.chempirical.com
- Yes, tested by running it: Page PNG was 2550 by 3300 pixels for US Letter. Opens the screenshot.High-resolution PNGPage PNG was 2550 by 3300 pixels for US Letter.chempirical.com
- Not establishedPaste to and from ChemDraw
- No: Word paste retains editable text; structures and arrows become pictures. Opens the cited page.Editable in Word or PowerPointWord paste retains editable text; structures and arrows become pictures.chempirical.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
- No: CSP frame-ancestors 'self' and X-Frame-Options SAMEORIGIN block external framing. Opens the cited page.Embed in your own appCSP frame-ancestors 'self' and X-Frame-Options SAMEORIGIN block external framing.chempirical.com