Can I use it in an tag?

Yes: GET /v1/chart-image?c= &api_key=… returns the PNG directly. Keep long configs in POST.

Chart Image API

Render bar, line, area, pie, doughnut, scatter and sparkline charts from a Chart.js-like JSON config as PNG or SVG, by a URL usable in <img> and emails.

GETPOSThttps://apibox.io.vn/v1/chart-image

Images & Codes▶ Try it online

Describe the chart in JSON and get an image: {"type":"bar","data":{"labels":[…],"datasets":[{"label":"…","data":[…]}]},"options":{"title":"…"}}. Types: bar, horizontal-bar (or Chart.js indexAxis: "y"), line, area, pie, doughnut, scatter (points {x, y}) and sparkline. Several datasets are grouped (or stacked: true), a dataset of a bar chart can be drawn as a line, gaps (null) break lines, and tension smooths them. Options: title, subtitle, legend (top, bottom, right, false), x_label / y_label, min / max, values (data labels), prefix / suffix (" ₫", "%"), locale (vi writes 1.234,5 and 12 tr / 3 tỷ on axes), theme (light / dark), font_size and colours per dataset (color, backgroundColor, an array for one colour per bar). The usual Chart.js keys (plugins.title, plugins.legend, scales.y.min, scales.x.stacked…) are understood, so most QuickChart-style configs work as they are.

Because it answers GET with the config URL-encoded in c, the URL can be put straight into <img src>, an e-mail, a Slack / Zalo message or a Markdown / PDF report. PNG (default) and JPEG are drawn by our own renderer with the Be Vietnam Pro font, so Vietnamese text looks the same everywhere; scale=2 gives a sharp image on retina screens. SVG keeps the text as vector outlines by default (exact rendering without fonts), svg_text=text writes real <text> elements instead.

Size: width × height up to 2000 px and 4 megapixels with scale, up to 20 datasets and 10,000 points. The colours follow a colour-blind-checked palette; the renderer is our own code (not QuickChart or Chart.js).

Parameters

Name	In	Type	Required	Default
`c`	query\|body	object	yes		Chart config (JSON; URL-encoded in GET): `type`, `data.labels`, `data.datasets`, `options`. `chart` is an alias.
`format`	query\|body	string	no	`png`	`png`, `svg`, `jpeg` or `json` (PNG as base64 + SVG).
`width`	query\|body	number	no	`600`	Width in pixels (50–2000).
`height`	query\|body	number	no	`400`	Height in pixels (30–2000).
`scale`	query\|body	number	no	`1`	Pixel ratio of PNG / JPEG (1–4), e.g. 2 for retina screens.
`theme`	query\|body	string	no	`light`	`light` or `dark` (also `options.theme`).
`locale`	query\|body	string	no	`en`	`vi` for Vietnamese number format (1.234,5; 12 tr; 3 tỷ).
`background`	query\|body	string	no		Background colour (`#fff`, `transparent`…).
`svg_text`	query\|body	string	no	`paths`	SVG only: `paths` (text as outlines) or `text` (`<text>` elements).

Example

curl "https://apibox.io.vn/v1/chart-image?c=%7B%22type%22%3A%22bar%22%2C%22data%22%3A%7B%22labels%22%3A%5B%22T1%22%2C%22T2%22%2C%22T3%22%5D%2C%22datasets%22%3A%5B%7B%22label%22%3A%22Doanh%20thu%22%2C%22data%22%3A%5B12%2C19%2C7%5D%7D%5D%7D%7D" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -o output

const res = await fetch('https://apibox.io.vn/v1/chart-image?c=%7B%22type%22%3A%22bar%22%2C%22data%22%3A%7B%22labels%22%3A%5B%22T1%22%2C%22T2%22%2C%22T3%22%5D%2C%22datasets%22%3A%5B%7B%22label%22%3A%22Doanh%20thu%22%2C%22data%22%3A%5B12%2C19%2C7%5D%7D%5D%7D%7D', {
  method: 'GET',
  headers: {
    Authorization: 'Bearer YOUR_API_KEY',
  },
});
const blob = await res.blob();

import requests

res = requests.get(
    "https://apibox.io.vn/v1/chart-image?c=%7B%22type%22%3A%22bar%22%2C%22data%22%3A%7B%22labels%22%3A%5B%22T1%22%2C%22T2%22%2C%22T3%22%5D%2C%22datasets%22%3A%5B%7B%22label%22%3A%22Doanh%20thu%22%2C%22data%22%3A%5B12%2C19%2C7%5D%7D%5D%7D%7D",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    timeout=30,
)
open("output", "wb").write(res.content)

<?php
$ch = curl_init('https://apibox.io.vn/v1/chart-image?c=%7B%22type%22%3A%22bar%22%2C%22data%22%3A%7B%22labels%22%3A%5B%22T1%22%2C%22T2%22%2C%22T3%22%5D%2C%22datasets%22%3A%5B%7B%22label%22%3A%22Doanh%20thu%22%2C%22data%22%3A%5B12%2C19%2C7%5D%7D%5D%7D%7D');
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => ['Authorization: Bearer YOUR_API_KEY'],
]);
$response = curl_exec($ch);
file_put_contents('output', $response);

Response

binary image/png

Use cases

Charts in daily report e-mails (sales, traffic, orders)
Images for Slack, Zalo or Telegram bot messages
Charts inside generated PDFs and Markdown reports
Sparklines and KPI images in dashboards without a JS library

FAQ

Can I use it in an <img> tag?

Yes: GET /v1/chart-image?c=<URL-encoded JSON>&api_key=… returns the PNG directly. Keep long configs in POST.

Is it compatible with Chart.js / QuickChart configs?

The common parts are: type, data.labels, datasets (label, data, backgroundColor, borderColor, fill, tension, type), indexAxis, plugins.title / legend, scales min / max / stacked.

Does Vietnamese text render correctly?

Yes, PNG and SVG draw text from the Be Vietnam Pro outlines, so diacritics are exact without any installed font.

Chart Image API

Parameters

Example

Response

Use cases

FAQ

Related APIs

QR Code Generator

Barcode Generator

Placeholder Image