Chart Image API

Charts that render anywhere — including email

Email clients can't run JavaScript, so a live dashboard chart dies in the inbox. POST a JSON payload here and get back a finished chart PNG that renders everywhere.

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A weekly active users line chart rendered as a static PNG image

report-chart.png · 960×540 · 2xrendered by the API

POST /api/v1/render · type: "chart" · format: "png" · line, bar, or pie

A static image is a feature, not a limitation

Line, bar, and pie out of the box

Pass a type in the JSON payload and get the matching chart style back, with labels, a legend, and per-dataset colors.

Deterministic, animation-free renders

Charts render synchronously with animation disabled, so identical input always produces identical output pixels — reliable for automated reports.

Works where a live <canvas> can't

Email digests, PDF reports, and chat unfurls all strip or block JavaScript. A rendered PNG works in every one of them.

How it works

1
Shape your chart as JSON
Provide a type, labels, and one or more datasets — the same structure you'd already hand to a charting library.

POST it with type: "chart"

Choose png for an inline image, or pdf to embed the chart in a multi-page report.

curl -X POST https://renderfy.io/api/v1/render \
  -H "Authorization: Bearer rfy_live_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "type": "chart",
    "content": "{\"type\":\"line\",\"labels\":[\"Mon\",\"Tue\",\"Wed\"],\"datasets\":[{\"label\":\"Signups\",\"data\":[12,19,7]}]}",
    "options": { "format": "png", "dimensions": { "width": 900, "height": 500 } }
  }' \
  --output chart.png

3
Embed the image anywhere
Drop it into an email template, a static report page, or a chat/webhook notification — no live chart library required on the receiving end.

Frequently asked questions

What chart types are supported?+

Line, bar, and pie — each fully configured through the type field in the JSON payload you send.

Can I actually put this chart inside an email?+

Yes — that's the primary use case. Because it's a static image rather than a live canvas, it renders identically across every email client, including ones that strip JavaScript entirely.

Can I control the color of each dataset?+

Yes. Each dataset in the JSON payload accepts its own color (or colors, for multi-slice charts like pie), so output matches your brand palette.

Can the chart go in a PDF report instead of a standalone image?+

Yes — the same JSON payload renders through the PDF output path as well, so the same chart definition works for both a standalone image and a multi-page report.

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Put your next chart where JavaScript can't reach

Sign up, mint an API key, and render your first chart image in the next 5 minutes — 100 free credits included — no card needed.

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