Fitspy review
A focused, scriptable desktop toolkit for constrained spectral peak fitting.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Fitspy is a GPLv3 Python application and library for fitting and decomposing one-dimensional and two-dimensional spectra. Scientists can work through PySide or Tkinter desktop interfaces, process individual spectra or batches with scripts, and import text, microscopy and HDF-based files through supported readers. Its audience is researchers who need spectral peak analysis rather than a general-purpose statistics environment.
The free, open-source package centers on detailed model control. Predefined peak choices include Gaussian, Lorentzian, asymmetric and Pseudovoigt forms, while background options cover constant, linear, parabolic, exponential and power-law behavior. Users can define models through expressions or Python scripts, then apply parameter bounds, fixing and coupling constraints. Automatic noise estimation and outlier detection support preparation, and multithreaded or multiprocess fitting addresses larger workloads. Saved JSON models can be replayed on other datasets, with fit results, statistics and parameters available for export.
Fitspy runs as desktop software on Windows, macOS and Linux, making it suitable for local laboratory workflows and scripted processing across major desktop platforms. Interactive two-dimensional map visualization adds context for spatially resolved acquisitions, while format support includes .txt, .dm3, .dm4, .emd, .hspy, .nxs, .h5, .h4, .hdf and NXCanSAS. Choose Fitspy when spectral models, constraints, reproducibility and batch scripting are central requirements. Teams seeking broad statistical methods beyond spectra or a non-desktop deployment should consider a different category of tool.
Fitspy pros and cons
- Where it wins
- Peak, background and custom Python model support
- Constraints, noise detection and multithreaded fitting
- JSON replay, 2D maps and exportable fit statistics
- Where it doesn't
- Focused on spectral fitting rather than general statistics
- Desktop deployment only across Windows, macOS and Linux
- Published support channel is documentation
Fitspy fact sheet, pricing and score →
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