Chart

The /chart endpoint generates charts from data. It supports bar, line, pie, and donut chart types, and returns either an SVG image or raw JSON data.

POST/v5/chart

Parameters

The request body must be JSON:

Parameter	Required	Description
type	Yes	Chart type: bar, line, pie, or donut
data	Yes	Chart data object (see structure below)
title	No	Chart title displayed above the chart
width	No	SVG width in pixels (responsive if omitted)
height	No	SVG height in pixels (responsive if omitted)
colors	No	Array of hex colors for datasets (defaults to a built-in palette)
bg	No	Background fill color (hex, transparent if omitted)
legend	No	Show legend: true (default) or false
mode	No	Response format: "svg" (default, returns SVG) or "data" (returns JSON)

Data Format

data must be a JSON object (not a string) in the request body. The structure depends on the chart type.

Bar and line charts:

{
    "labels": ["Jan", "Feb", "Mar"],
    "datasets": [
        { "label": "Sales", "values": [120, 200, 150] },
        { "label": "Costs", "values": [80, 95, 110] }
    ]
}

Pie and donut charts:

{
    "labels": ["Jan", "Feb", "Mar"],
    "values": [120, 200, 150]
}

• labels: array of strings — max 20 labels
• datasets (bar/line): array of dataset objects — max 5 datasets, each with a label and a values array matching the length of labels
• values (pie/donut): single array of non-negative numbers matching the length of labels

The data field must be a JSON object, not a JSON string. Send the request with Content-Type: application/json.

Response

• When mode is "svg" (default): returns Content-Type: image/svg+xml with the SVG body
• When mode is "data": returns a JSON object with the chart data

Code Examples

curl -X POST \
  -H "Content-Type: application/json" \
  -d '{
    "type": "bar",
    "data": {
      "labels": [
        "Jan",
        "Feb",
        "Mar"
      ],
      "datasets": [
        {
          "label": "Sales",
          "values": [
            120,
            200,
            150
          ]
        }
      ]
    },
    "title": "Monthly Sales"
  }' \
  "https://api.sylvain.sh/v5/chart"

Try It

POSThttps://api.sylvain.sh/v5/chart

type*Select...barlinepiedonut

data*

title

width

height

colors

bg

legendSelect...truefalse

modeSelect...svgdata

Error Handling

If parameters are missing or invalid, the API will return an error:

Error Message	Description
Please provide a valid chart type (?type=bar|line|pie|donut)	The type parameter is missing or invalid
data must contain a labels array	The data.labels field is missing
data must contain a datasets array	The data.datasets field is missing
Too many labels (max 20)	The labels array exceeds 20 entries
Too many datasets (max 5)	The datasets array exceeds 5 entries
Each dataset must have the same number of values as labels	Dataset length mismatch