Chart APIs
Create line, bar and pie charts
Chart APIs turn your numbers into a chart without a charting library in your own code: you send the data in a URL or a request and get back an image you can put in a web page, an e-mail or a report. Some also draw diagrams from text.
GXChart WebChart
GXChart WebChart is a SOAP web service that creates chart images from your data: bar, line, pie and other chart types, with titles, legends and colours. Call it from any SOAP client, for example in .NET or PHP, and use the ...
Image-Charts
Image-Charts creates chart images (pie, bar, line, radar, QR codes and more) from a URL, using the same parameters as the retired Google Image Charts, so old chart URLs keep working by changing the domain. It also offers ...
Kroki
Kroki turns text diagram descriptions into images with one simple API: PlantUML, Mermaid, GraphViz, BPMN, C4, D2, Excalidraw, Vega charts and more than twenty other formats. Send the diagram source by POST, or encoded in the URL ...
mermaid.ink
mermaid.ink turns Mermaid diagram code into images: flowcharts, sequence diagrams, Gantt charts, pie charts and more, for example to show a diagram in a README or e-mail. Encode the diagram (as the Mermaid Live Editor does) and ...
QuickChart
QuickChart turns a chart definition in the URL into a chart image, using Chart.js syntax: bar, line, pie, doughnut, radar and many more types, as PNG, SVG or PDF. That makes it easy to put charts in e-mails, Slack messages, PDFs ...
Compare the chart APIs
| Service | API key | Formats | Free use |
|---|---|---|---|
| GXChart WebChart | Not needed | XML | – |
| Image-Charts | Not needed | – | The free plan is free forever with unlimited charts, but adds a small 'image-charts.com' watermark; paid plans remove it. |
| Kroki | Not needed | – | Free public server; open source, so you can also run it yourself. |
| mermaid.ink | Not needed | – | Free and open source, no key needed. |
| QuickChart | Not needed | – | Free plan with a monthly limit; paid plans for more charts. |
Questions
Which free chart APIs work without an API key?
GXChart WebChart, Image-Charts, Kroki, mermaid.ink and QuickChart work without a key, according to their documentation. Most keyless services ask you to keep the number of requests reasonable, and some ask for a User-Agent that names your app.
Are these chart APIs really free?
The services here can be used without paying, at least on a free plan or free tier, often with limits such as a number of requests per day or non-commercial use only. The table above quotes what each service says about its free use; check the provider's own terms before you rely on it.
How up to date is this list?
The address of every service is checked about once a week, and services that stop working or stop being free are removed. This list last changed on November 8th, 2026.