Engines
Burette uses several preview paths. The route depends on the file type and the runtime surface.
Mol*
Mol* is the default interactive 3D path for most structure files, including PDB, CIF, BinaryCIF, MMTF, SDF, MOL, MOL2, XYZ, and GRO where supported by the runtime. It also renders CCP4/MRC/MAP density volumes, MTZ reflection maps, and MolViewSpec scenes and Stories.
Use Mol* when you need interactive structure inspection, trajectory-aware controls (including smoothed playback), structure superposition, or Maestro/PyMOL-style structure operations such as chain splitting, selection tooling, measurements, and colour presets.
Mesoscale viewer
Cell-scale crowded scenes (molj, molx, .mesozip packages, and CellPack/Petworld-style CIF files) open in a dedicated Mol* Mesoscale Explorer runtime with its own hierarchy panel, selection, and export surface. It is a separate runtime from the standard Mol* viewer, tuned for large numbers of repeated molecular instances.
RDKit grids
RDKit powers collection views for SDF, SMILES, CSV, TSV, and DataWarrior (.dwar) files; DataWarrior structures decode locally through the bundled OpenChemLib runtime, and CSV/TSV without molecule columns still open as data tables.
Use the grid when you need search, sorting, SMARTS filtering and highlighting, row selection, append and merge workflows, export, or the native compute actions (clustering, similarity search, conformers, and Chemical Space).
Spectrum viewer
Mass-spectrometry formats (MS, MAGMA, MGF, MSP, MZML, MZXML) open in a dedicated spectrum viewer instead of a structure renderer.
External xyzrender
xyzrender is an optional local executable used for artwork-style SVG rendering and format-specific fallback previews.
XYZ and several quantum-chemistry inputs can use xyzrender when the active renderer policy selects it. Burette also has coordinate-conversion paths for ABI, COM, CUB/CUBE, FDF, FHIAIMS, GMS, IN/INP, LOG, NW/OUT, PSI4, QCIN, VASP, and XYZR, and a separate Maestro conversion path for MAE/MAEGZ/CMS. If conversion cannot produce coordinates, the external renderer remains the fallback rather than a silently fabricated structure.
Multi-frame XYZ files stay in Mol* when Burette detects trajectory content so the native trajectory controls can show the available frames.
VESTA handoff
CUBE, CIF, MMCIF, MCIF, XYZ, and external-renderer input previews expose an optional VESTA handoff when VESTA is installed.
Calculation engines are separate
xTB, CREST, and PRISM are local calculation executables, not preview renderers. Burette prepares bounded inputs, runs cancellable jobs, and opens reports and artifacts, while Mol*, RDKit, or the text viewer display their outputs. xTB can also be installed as a managed Conda environment directly from Settings, so it no longer requires a manual install.
Separately from these external executables, Burette ships a native Apple Silicon compute layer (CPU with Metal GPU acceleration) for clustering, similarity search, conformer generation, MMFF optimization, alignment and scoring, semiempirical energies, and Chemical Space embeddings. It runs inside the app with no external installation.