Description

NeXusCreator

NeXusCreator is a Python-based software toolkit for converting heterogeneous experimental data into standards-compliant NeXus (HDF5) files — usable from the command line, a Python API, a REST API, or a local web GUI.

Experimental instruments produce data in many incompatible formats, making long-term storage, sharing, and reproducibility challenging. NeXusCreator addresses this by automating the transformation of raw data into structured, metadata-rich NeXus files, following community standards used in photon, neutron, and muon science.

Key Capabilities

Automated data conversion
Convert raw files (e.g. SPEC, Gamry DTA/DAT, HDF5 — including EVE and Roundrobin instrument variants —, TIFF, JSON, YAML, JSON-LD) into NeXus (.nxs) format — for single files or entire directories.

Template-based workflows
Generate reusable .nxd definition templates directly from input data. Templates support scan and multi-file expansion, prompt literals for missing metadata (placeholders flagging required manual input), and optional NXDL schema-guided field placement via SchemaPlacer — which ranks candidate NeXus locations for a variable using its name, schema context, units, and description, optionally sharpened further with an external metadata CSV — enabling consistent, repeatable, and FAIR data transformations.

Batch and large-scale processing
Process individual files or large datasets, including combined outputs for multi-file experiments (e.g. a whole operando run folder into one file). Per-scan outputs with HDF5 external links are supported for SPEC workflows.

Domain-specific workflows
Built-in support for XAS (IKFT/Diamond B18/operando via EVE HDF5), electrochemistry and operando EIS (batteries/DTA, including derived State-of-Charge/IV/EIS datasets), photoemission (PEAXIS), and MPES experiments, with dedicated parsers and generators. For Raman, XAS, and XPS, NeXusCreator also bridges directly to the real reader plugins from the pynxtools/NOMAD ecosystem, instead of reimplementing vendor-format parsing.

Extensible plugin architecture
A priority-based plugin system auto-discovers parsers and generators at runtime. Supporting new formats requires only a single plugin file — no core modifications.

Standards-compliant structuring and native validation
Supports schema-guided placement via NXDL application definitions (e.g. NXxas), correct use of NX_class, signals, axes, and @default chains, with a native, dependency-free structural validator (h5py-only — no external tool required) checking the written file against the same rules.

Multiple interfaces for pipeline integration
A public Python API (create_nexus, NeXusCreator) enables seamless integration into automated workflows and data processing pipelines. The same conversion engine is also exposed as a REST API for scripting from any language or tool, and as a local web GUI — with an embedded, syntax-highlighted .nxd editor and an embedded H5Web viewer for the resulting .nxs — for anyone who prefers a browser to the command line.

Why NeXusCreator?

NeXusCreator bridges the gap between instrument-specific raw data and FAIR, reusable scientific datasets. It enables:

• Reproducible data pipelines
• Consistent and standards-compliant metadata integration
• Interoperable data for cross-facility use and analysis

By separating data extraction (parsers) from data structure definition (.nxd templates), NeXusCreator provides a scalable and flexible foundation for managing complex experimental data workflows. That same .nxd mapping format is also consumed independently by other tools, such as HZDR's nexus-design-studio.

Typical Use Cases

• Converting beamline data (SPEC, XAS, MPES, EIS) into NeXus for archiving and analysis
• Standardising electrochemical and operando experiment datasets
• Bridging existing NOMAD/pynxtools readers (Raman, XAS, XPS) into NeXus without writing a new parser
• Preparing data for facility data management systems and repositories (e.g. ICAT)
• Automating data pipelines in large experimental campaigns, via the CLI, Python API, or REST API
• Reviewing and converting data through a browser, without installing anything locally beyond the web GUI

One-Line Summary

Convert heterogeneous experimental data into standards-compliant NeXus (HDF5) files using reusable, NXDL-aware mapping templates — reproducibly and at scale, via CLI, Python API, REST API, or web GUI.