Fitspy
Fitspy: A focused, scriptable desktop toolkit for constrained spectral peak fitting. Ranked #55 of 106 in Statistical Analysis Software by our editors (3.9/10); pricing: Free plan; best for scientists fitting and visualizing spectral peaks.
At a glance
- Editor score3.9 / 10
- PricingFree plan
- Best forScientists fitting and visualizing spectral peaks
- Free planYes
- Paid fromFree
- DeploymentDesktop
- Facts checked23 Sep 2026
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
Our verdict on Fitspy
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.
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Fitspy pricing
Fitspy fact sheet
| Free plan | Yes |
|---|---|
| Paid from | Free |
| Deployment | Desktop |
| Statistical tests | Not verified |
| Regression models | Not verified |
| Scripting support | Yes |
| Bayesian analysis | Not verified |
| Data import formats | .txt; .dm3; .dm4; .emd; .hspy; .nxs; .h5; .h4; .hdf; NXCanSAS |
| Deployment | Desktop |
| Platforms | Windows, macOS, Linux |
| Support | Docs |
| Built for | Solo, Small business, Mid-market, Enterprise (editorial estimate) |
| Pricing | Free plan |
| Website | github.com |
| Facts checked | 23 Sep 2026 |
Alternatives to Fitspy
- RA free, programmable environment for statistical analysis, modeling, visualization, and data import.9.4
- StataA broad, scriptable desktop environment for professional and reproducible applied analysis.9.3
- IBM SPSS StatisticsA broad desktop statistics suite with testing, modeling, forecasting, reporting, and R/Python integration.9.2
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
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