Useful by design.
Open by intention.
ChartsAI is a collection of free visual tools built by SupaMakers. We want making a chart or printing a tracker to feel like a small, satisfying task.
A finished example is a better start.
Every tool starts with something you can use immediately. You can explore the example, replace its data, and download the result. Our original teaching examples are explicitly fictional and demonstrate the tools, not real-world findings. Separately, our UCI datasets and NASA/World Bank resources retain primary sources, selection notes and attribution. Each editorial template identifies whether its data is fictional or sourced.
Keep the meaning intact.
A pretty chart is only useful when it represents the values you meant to show. Our import preview lets you select a sheet, choose columns, and specify number formatting. We flag missing or invalid values instead of replacing them with zero. We do not remove outliers, infer business metrics, or normalize mixed units without your involvement.
Dot plots
Each selected observation produces one dot. Identical numeric values stack at the same horizontal position. No automatic binning or rounding is applied to the observations. The frequency table exposes the counts behind the drawing. The mean, median and range use the included observations; the display formats values to a maximum of six decimal places.
This implementation is for frequency dot plots. It supports up to 300 observations. Very close values can be visually crowded; use the frequency table to inspect their exact values. The chart is not a substitute for checking the underlying data.
Radar charts
Axes share a zero-to-maximum scale, and score positions vary linearly along each axis. All series use the same dimension order. Missing, negative and out-of-range values are flagged. Changing axis order changes the shape, so the enclosed area is not presented as an overall score. For more context, see Data to Viz’s discussion of radar charts.
Line graphs
Line graphs connect observations in the supplied row order. Equal spacing treats labels as categories; numeric distance and UTC date spacing preserve actual intervals. Numeric/date positions must be strictly increasing. Missing values, impossible dates and duplicate positions are flagged rather than guessed. Values are not smoothed, forecast, aggregated or normalized. All series share one vertical scale, with zero included by default.
Distributions and relationships
Histograms declare bin boundaries and retain all observations. Box plots state the quartile and whisker conventions and keep outliers visible. Scatter plots retain paired values; a fitted line does not establish causation. Bar charts include zero, and Pareto charts separate the value scale from cumulative percentages. The method guides explain these choices with checkable calculations.
Publication charts
Dumbbells compare two measurements per group; slopegraphs compare endpoints without claiming the intervening path. Small multiples use shared scales. Captions, units, sources and data-anchored annotations travel with editable publication projects. Replacing sample data clears unchanged sample claims and annotations.
Mathematical diagrams and worksheets
Coordinate planes and transformations preserve equal physical units. Slope calculations distinguish vertical lines from repeated points. Quadratic diagrams disclose their independent axis scales. Practice sheets separate questions from answer keys; we claim no curriculum certification. Each math tool states its own limits and method.
The chart worksheets derive reading, comparison and drawing questions from the selected values. Whole-number limits are explicit; repeated dot observations, category ties and zero values are retained. Drawing questions and answer keys share the same scale. Median, mode, frequency and change answers are calculated from the current data.
Habit trackers
Monthly layouts use the Gregorian calendar and include leap-year February. Weekly layouts use Monday through Sunday with a blank start-date field. The PDF uses the selected A4 or US Letter dimensions. This is a printable template, not a health assessment or a behavior-change guarantee.
Proven rendering. Open implementation.
The chart makers use Apache ECharts’ built-in scatter, radar, line, bar and boxplot series. Our application provides the data validation, presentation settings and examples. The same option builders drive the static previews, interactive editors and exports. Chart PDFs contain a high-resolution image; SVG exports retain vector shapes and text. Number lines, coordinate diagrams and worksheet grids use shared SVG geometry. Static pie/logarithmic teaching illustrations are labelled separately from interactive maker capabilities.
Your input stays with you.
Parsing, calculations and file generation happen in your browser. We do not receive your spreadsheet or habit list. There is no account or cloud history; download your data or finished output before closing the page. Read the privacy details.
Made to be used, and learned from.
Charts, trackers and sample datasets are free to use. The implementation is available under the MIT license, so you can inspect the logic and adapt it. Download the source code and read the reuse notes.
How we review changes
SupaMakers maintains the implementation and explanations. We check calculations against explicit fixtures, compare source values with plotted/exported values, and inspect representative mobile layouts and downloaded outputs. Primary data pages document their sources, periods and selections. These checks are not independent statistical peer review. Report a reproducible issue through our feedback email; review dates change when the resource is actually reviewed.
The makers
SupaMakers builds practical software and AI systems. ChartsAI is one of our public projects: a small place to make useful things, publish our choices, and improve them through use.
Found a calculation issue, confusing input, or a layout that needs attention? Send feedback to support@chartsai.com. Include a fictional or anonymized example when possible.
Looking for a starting point? Make a dot plot, compare a radar chart, or print a habit tracker.
Contact
For feedback or questions, email support@chartsai.com. For bugs and improvements, send a reproducible report using fictional sample data.