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Chemvas — Draw interactively. Automate safely. Export exactly.

CI PyPI Python 3.12+ License: MIT

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Chemvas is an open-source chemical drawing app where chemists and AI agents work on the same editable canvas. Start in the desktop app, let an agent continue through a purpose-built CLI, then open the editable result right back on the canvas.

Draw it yourself. Hand it to AI. Keep editing.

  • Draw it yourself. Sketch structures, insert SMILES, label reaction arrows, and align molecules on the desktop canvas, with autosave and crash recovery. SMILES insertion needs the optional RDKit backend.
  • Hand the same drawing to an AI agent. The CLI can compose documents, inspect stable atom IDs, apply bounded graph patches, check layouts, and render figures without opening the desktop app. Graph Patch binds each proposal to the exact source hash and validates the complete result before writing a new file.
  • Keep editing the result. Composed and patched drawings remain native, reopenable .chemvas documents. Export SVG, PDF, PNG, or TIFF at explicit physical sizes while keeping the editable drawing alongside the figure.

Install

Requires Python 3.12+. Install the optional RDKit backend for SMILES insertion, Molecule Info (formula and identifiers), 3D XYZ export, abbreviation MOL export, Suggest by structure, and generate-precomplex / select-precomplex / pack-step:

pip install "chemvas[rdkit]"
chemvas

pip install chemvas skips RDKit. Drawing, .chemvas save/open, figure export (SVG/PDF/PNG/TIFF, including editable SVG), and plain MOL import/export remain available. Local Windows builds: packaging notes.

Your first reaction scheme

Chemvas walkthrough: insert structures, label an arrow, align the scheme, and export SVG

  1. Choose Ring, type OCc1ccccc1 in its SMILES field, click Insert, then click the canvas. Hover the oxygen, press Enter, label it OH.
  2. Insert O=Cc1ccccc1 to the right. Choose Arrow, drag between the two structures, then double-click the arrow to label it.
  3. Edit ▸ Select All, then Edit ▸ Align ▸ Middle.
  4. Save as .chemvas. File ▸ Export Figure… → Plain SVG, Fit 2-column (174 mm).

The step-by-step guide has the label text and the downloadable files. The drawing is an exercise, not an experimental result.

Scripts

With the downloaded first-scheme.chemvas:

chemvas inspect-document first-scheme.chemvas
chemvas check-layout first-scheme.chemvas
chemvas render-document first-scheme.chemvas --output first-scheme.pdf --width-mm 174

Rendering writes a new file and never touches the source. Composition, Graph Patch, scheme layout and their limits: document CLI guide · scheme layout · publication recipe.

Documentation

Something got in your way? Open an issue.

Release files for chemvas 0.13.0

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Source distribution for chemvas 0.13.0
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chemvas-0.13.0-py3-none-any.whl Python 3 none any Details

Total release size: 1.6 MB

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0.20.0

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0.19.0

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0.18.0

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0.17.1

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0.16.0

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0.14.1

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0.14.0

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0.13.0 This release

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0.12.0

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0.11.0

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0.9.0

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0.8.4

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0.5.1

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