Chart Splat

Generate beautiful charts from data using the Chart Splat API. Charts are rendered server-side with Chart.js and returned as PNG images.

Supported Chart Types

| Type | Best For |

|------|----------|

| line | Trends over time |

| bar | Comparing categories |

| pie | Parts of a whole |

| doughnut | Parts of a whole (with center space) |

| radar | Multivariate comparison |

| polarArea | Comparing categories with radial layout |

| candlestick | Financial/crypto OHLC price data |

| ohlc | Financial/crypto OHLC price data (bar variant) |

Method 1: CLI (Preferred)

Use the chartsplat CLI via npx. No install required.

npx -y chartsplat-cli bar \
  --labels "Q1,Q2,Q3,Q4" \
  --data "50,75,60,90" \
  --title "Quarterly Revenue" \
  --color "#8b5cf6" \
  -o chart.png

CLI Options

| Flag | Description |

|------|-------------|

| -l, --labels <csv> | Comma-separated labels |

| -d, --data <csv> | Comma-separated numeric values |

| -t, --title <text> | Chart title |

| --label <text> | Dataset label for legend |

| -c, --color <hex> | Background color |

| -w, --width <px> | Image width (default: 800) |

| --height <px> | Image height (default: 600) |

| -o, --output <file> | Output file path (default: chart.png) |

| --config <file> | JSON config file for complex charts |

CLI Chart Commands

npx -y chartsplat-cli line -l "Mon,Tue,Wed,Thu,Fri" -d "100,200,150,300,250" -o line.png
npx -y chartsplat-cli bar -l "A,B,C" -d "10,20,30" -o bar.png
npx -y chartsplat-cli pie -l "Red,Blue,Green" -d "30,50,20" -o pie.png
npx -y chartsplat-cli doughnut -l "Yes,No,Maybe" -d "60,25,15" -o doughnut.png
npx -y chartsplat-cli radar -l "Speed,Power,Range,Durability,Precision" -d "80,90,70,85,95" -o radar.png
npx -y chartsplat-cli polararea -l "N,E,S,W" -d "40,30,50,20" -o polar.png
npx -y chartsplat-cli candlestick --config ohlc.json -o chart.png

Candlestick Charts

Candlestick and OHLC charts require a JSON config file since the data format is more complex than a simple CSV list. Use --config to provide a file with OHLC data points.

npx -y chartsplat-cli candlestick --config ohlc.json -o candlestick.png

Config format (ohlc.json):

{
  "type": "candlestick",
  "data": {
    "datasets": [{
      "label": "VVV Price",
      "data": [
        { "x": 1740441600000, "o": 4.23, "h": 4.80, "l": 4.10, "c": 4.45 },
        { "x": 1740528000000, "o": 4.45, "h": 5.50, "l": 4.30, "c": 5.34 },
        { "x": 1740614400000, "o": 5.34, "h": 6.20, "l": 5.10, "c": 5.97 }
      ]
    }]
  }
}

Each OHLC data point requires: x (numeric timestamp in ms, or a date string like "2025-02-25"), o (open), h (high), l (low), c (close).

Complex Charts via Config File

For multi-dataset or customized charts, write a JSON config file then pass it to the CLI:

npx -y chartsplat-cli bar --config chart-config.json -o chart.png

See examples/sample-charts.json for config file examples and references/api-reference.md for the full config schema.

Method 2: Helper Script

Use the bundled script for quick generation without installing the CLI:

node scripts/generate-chart.js bar "Q1,Q2,Q3,Q4" "50,75,60,90" "Revenue" chart.png

Or with a config file:

node scripts/generate-chart.js --config chart-config.json -o chart.png

Output Handling

• Charts are saved as PNG files to the specified output path
• Default output is chart.png in the current directory
• For messaging platforms (Discord, Slack), return the file path: MEDIA: /path/to/chart.png
• The CLI and helper script handle base64 decoding automatically

Error Handling

| Error | Cause | Fix |

|-------|-------|-----|

| API key required | Missing CHARTSPLAT_API_KEY | Set the env var in agent config |

| Invalid API key | Wrong or revoked key | Generate a new key at chartsplat.com/dashboard |

| Rate limit exceeded | Monthly quota reached | Upgrade plan or wait for reset |

| Invalid chart configuration | Bad request payload | Check that data.labels and data.datasets are present (candlestick/ohlc only require data.datasets) |

Tips

• Always provide both labels and data arrays of the same length
• Use hex colors (e.g., #8b5cf6) for consistent styling
• For pie/doughnut charts, use an array of colors for backgroundColor to color each segment
• Default dimensions (800x600) work well for most uses; increase for presentations
• The --config flag accepts any valid Chart.js configuration for full customization