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Curcat — Curve Catcher

Turn curves in chart images into reusable data.

Curcat is a desktop graph digitizer for extracting numerical data from plots, scans, and screenshots. Calibrate the axes, pick a curve manually or trace it automatically, then export the result for further analysis.

Features

• Cartesian and polar coordinate systems
• Linear and logarithmic axes, with numeric and date/time values
• Manual point picking and automatic curve tracing
• Linear, step, and natural cubic spline interpolation
• CSV, JSON, RON, XLSX, HTML, XML, and Markdown export
• Project files for saving and resuming your work
• English and Russian interface
• PNG, JPEG, GIF, BMP, TIFF, WebP, ICO, TGA, PNM, HDR, DDS, SVG, and SVGZ input

Install and run

Download a release

1. Open the latest release.
2. Download the archive for your platform:
   • linux-x86_64 for 64-bit Linux;
   • windows-x86_64 for 64-bit Windows;
   • macos-aarch64 for Apple silicon Macs.
3. Extract the archive and run curcat (curcat.exe on Windows).

On Linux or macOS, start Curcat from a terminal in the extracted directory:

chmod +x curcat # only needed if the executable bit was lost during extraction
./curcat

On Windows, double-click curcat.exe or run it from PowerShell:

.\curcat.exe

You can pass an image path to open it immediately:

./curcat path/to/chart.png

.\curcat.exe "C:\path\to\chart.png"

Install from source

Curcat currently requires the Rust nightly toolchain. Install Rust with rustup, then run:

rustup toolchain install nightly
cargo +nightly install --git https://github.com/hexqnt/curcat --locked
curcat

On Linux, the build also requires the standard X11/Wayland and OpenGL development packages for your distribution.

To install a local checkout instead:

git clone https://github.com/hexqnt/curcat.git
cd curcat
cargo +nightly install --path . --locked

Quick start

1. Open an image using the file picker, drag and drop, or Ctrl+V.
2. Choose Cartesian or polar coordinates and calibrate the axes using known values on the chart.
3. Click along the curve to add points, or use automatic tracing. Hold Shift and drag to adjust a point or calibration line.
4. Choose Interpolated curve for evenly spaced samples or Raw picked points for the original selections.
5. Select an export format and save the data.

Curcat accepts dates such as YYYY-MM-DD, YYYY-MM-DD HH:MM[:SS], DD.MM.YYYY, and YYYY/MM/DD.

Shortcuts

Shortcut	Action
Left click	Add a point
Shift + drag	Move the nearest point or calibration line
Middle mouse button	Pan the image
Ctrl + mouse wheel	Zoom
Ctrl+O	Open an image
Ctrl+V	Paste an image
Ctrl+S	Save the project
Ctrl+Shift+P	Load a project
Ctrl+B	Show or hide the side panel
Ctrl+Z	Undo the last point
Ctrl+Shift+D	Clear all points

Export shortcuts are shown next to their commands in the application.

Configuration

Curcat works without a configuration file. To customize colors, interaction settings, export limits, or the interface language, copy and edit the provided curcat.toml. Place it next to the executable or in your platform's Curcat configuration directory.