Open Tools · Applied math, statistics and data
Curvewright: free online data plotting and curve fitting tool
Curvewright turns a table of measurements into a publication-ready figure and a documented fit. Paste data from a spreadsheet, choose a chart, and fit a straight line, a polynomial, a built-in model such as a Gaussian peak or a Michaelis-Menten curve, or an expression of your own.
Fits report parameters with standard errors and intervals, a correlation matrix, R-squared and information criteria, residual plots and confidence and prediction bands. Smoothing, interpolation and export to SVG, PDF and PNG at the size of your page are built in, and the Guide states what Curvewright does not do.
What Curvewright can do
- Paste or import CSV and TSV data into an editable table
- Scatter, line, error-bar, bar, histogram and box charts, log and dual axes, multi-panel layouts and annotations
- Linear, polynomial and nonlinear least squares with weights, bounds and fixed parameters
- Safe model expressions and a library of common curves
- Parameter intervals, correlation matrix, residual plots, R-squared, AIC and BIC, confidence and prediction bands
- Moving-average and Savitzky-Golay smoothing, interpolation, and export to SVG, PDF and PNG
How we verify Curvewright
Curvewright is checked against 272 independent reference cases. Where a reference answer exists you can run every check yourself on the Verify page, and the Curvewright user guide documents every feature and limitation.
Curvewright is checked with published reference datasets, independent numerical references, hand calculations and self-consistency properties. These checks cover representative cases rather than every possible input. The checks are in the tool: open Verify to run all 272 of them in your own browser and see, for each, what is compared, the reference, the computed value, the difference, the tolerance and PASS or FAIL. The same case list is run by the project's automated tests, so what you see is what is checked before release.
Curvewright is part of Open Tools, the free engineering tools that run in your browser.
Professional use. Results are for education and preliminary design. They must be checked by a qualified professional, and they are not a substitute for code-compliant design or licensed engineering judgement.