Tools
HAVA Laboratory · Free research tools
Tools
Browser tools for research figures and documents: plot and digitize data, edit PDFs, draw flow charts and touch up images. Everything runs on your computer; files are never uploaded.
Data Digitizer
A self-contained browser digitizer for plot images. Select a figure, define the plot area, calibrate the axes, and extract points or color-matched curves entirely in the browser.
Image workspace
Choose a plot image, then drag to define the plot box. Click inside the box to add manual points, then place one seed point on the target curve before running auto extraction.
Axis calibration
The plot box can be set manually on the canvas. Add an orange legend exclusion box when the legend overlaps the plot. Use log scale only with positive axis limits.
Colorbar calibration
Drag a box just inside the colored part of the colorbar.
Each pixel in the plot box gets the value of the closest colorbar color. Pixels with no close color (the body, background, labels, white streamlines) become no-data; gaps thinner than the fill size are filled from both sides. Tolerance sets how close a color must be; Sample step sets the grid spacing in pixels.
Results
PDF Tools
Add text, dates, signatures, and stamps to a PDF, or merge and split PDFs. Everything runs in your browser; files are never uploaded.
Edit / Sign
Drag items to place them. Select an item and press Delete to remove it; drag the corner handle to resize. With Edit text, click (Shift+click to add) or drag a box over the page's text, then Delete or Replace it; double-click a piece of text to retype it directly. Highlight marks the text you click or drag over. Add comment pins a small marker where you click; hover it to read the comment, double-click it to change it (in the downloaded PDF it is a normal PDF comment). Erase area covers any region with the page's background color. Covers are normal items: select one and press Delete to bring the original back.
Text
Arial, Times New Roman and Courier New add nothing to the file size. Other fonts (and these three when the text has characters such as ğ, ş, ı) are embedded in the PDF, adding roughly 0.2–0.5 MB per font style.
Signature
Stamp
PDF stamps use the first page.
Merge PDFs
Split PDF
Compress PDF
Text, fonts and vector graphics are kept as they are (sharp and selectable); only the images inside the PDF are downsampled and recompressed, so PDFs with photos, figures or scans shrink the most. If no smaller file can be made, the original is kept and nothing is downloaded. Uses Ghostscript compiled to WebAssembly, downloaded on demand (about 16 MB the first time).
HAVAPlot
Make line or contour plots from CSV, DAT or VTK files (legacy .vtk and XML .vtu, .vtp, .vts, .vtr, .vti) and export them as PNG, EPS or PDF. Everything runs in your browser; files are never uploaded.
Preview
Drag a box on the plot to zoom in. Double-click or use Reset zoom to restore the full view.
Data
Variable calculator
Write data
Surface data
Lagrangian particles
Series
Probe
Move the cursor over the plot. Line plots: the line reads every series where it crosses them. Contour and 3D plots: the values at the point under the cursor (in 3D, on a slice plane or a face of the domain). Click the plot to hold the probe in place; click again to let it follow the cursor.
Contour
Streamlines
Placed seeds (Place streamlines by clicking): a click puts a seed on the nearest plane or box face under the cursor, anywhere in the domain; a drag puts a rake along a straight line between its two ends. Or type a point above.
Whole volume: lines start from an n × n grid of points on the current slice plane (move the slice to the inlet to seed from there) and follow the 3D velocity both ways or as set in Direction.
Mesh
Isosurfaces (3D)
Surfaces where the variable has the same value, drawn in the 3D view and in exports. Levels are spread evenly between Min and Max (the data range if empty). Lower the opacity to see the inner surfaces.
Extract line data
Text on plot
Drag text on the plot to move it; double-click it to edit; Delete removes the selected text. Text stays attached to its data position when you zoom.
Shapes and images
Pick a shape, then drag on the plot from one end (or corner) to the other; a plain click puts a default-size shape there. Insert image puts a picture in the middle of the plot (line width draws a frame around it). Click a shape to select it, drag it to move it, drag its square handles to reshape it; Delete removes it. The settings above change the selected shape (and are used for new ones). Shapes stay attached to their data position when you zoom.
Multi-panel figure
Zoom inset
Add as many insets as you like: each repeats the plot for its region at the same color scale. Drag an inset to move it, also off the plot into the free space; click it and press Delete (or use Delete inset) to remove it. Tick labels that would overlap are thinned out automatically (the tick numbers you enter are a maximum). Insets are included in PNG, EPS and PDF exports.
Labels and axes
Min / max crop the 3D box to that part of the domain. Axis label size and Tick size above set the size of the axis titles and numbers.
To give a series its own scale, set its Y axis to Right or X axis to Top under Series. The top/right min and max apply to those axes.
Design
Transparent leaves the background out of PNG, EPS and PDF exports (useful on slides). Turn on Grid under Labels and axes to see grid lines (it can also go on top of the data, with its own intensity).
Flow Chart Maker
Build flow charts from boxes, terminators, decisions and I/O blocks, connect them with arrows, and export PNG, EPS, PDF or TikZ code. Everything runs in your browser.
Flow chart
TikZ code
Paste TikZ code here and it is drawn on the canvas right away, or edit the code and press Draw on canvas (Ctrl+Enter). Boxes become editable shapes: \node with styles (\tikzstyle, \tikzset), positions (at (x,y), below of=a, below=of a), colors such as red!30, and \draw arrows with --, -|, |- and labels. Curves, \foreach and \matrix are skipped.
Edit
Click a box or an arrow to edit it. Use Connect to draw an arrow between two boxes. Text accepts LaTeX math between dollar signs, such as $\rho$, $t_{n+1}=t_n+\Delta t$ or $\mathbf{U}$. It is drawn as vector text in PNG, EPS and PDF (Greek letters, common symbols, sub/superscripts, simple fractions); TikZ output keeps the LaTeX as typed.
Images are included in the PNG export and saved project file. EPS, PDF and TikZ exports show a placeholder.
Drag the label text on the canvas to put it anywhere; it then moves with its arrow. For text that is not tied to an arrow, use + Add shape → Text. Drag an orange end point onto any side of a box (or onto another box) to choose where the arrow attaches. Shape the path on the canvas: drag a square corner or a round segment handle, double-click the line to add a corner and double-click a corner to remove it.
Arrows
Image Editor
A light image editor for figures and photos. Open PNG, JPEG, EPS or PDF, delete or erase parts, pick and fill colors, add text, arrows and shapes, then crop, trim, rotate or resize. Export PNG, JPEG, EPS or PDF. Everything runs in your browser; images are never uploaded.
Image
Color
Selected:
Text defaults
Selection
Image
New / import settings
Shortcuts: F full screen (Esc leaves), V select, B brush, E eraser, G fill, I pick color, T text, L line, A arrow, R rectangle, O ellipse, Delete removes the selected object or selected pixels, arrow keys nudge, Ctrl+Z / Ctrl+Y undo / redo, Ctrl+wheel zooms. Text and shapes stay editable until you flatten or export. EPS files are rendered with Ghostscript (AGPL) compiled to WebAssembly, downloaded on demand (about 16 MB the first time).
Designed and developed by Ozgur Tumuklu.
For issues or suggestions, please use the contact page.
© 2026 Ozgur Tumuklu. All rights reserved. The code of these tools may not be copied or reused without permission.