canonical: https://jentic.com/apis/image-charts.com/image-charts

# Image-Charts

Image-Charts renders charts as static images directly from a URL. It positions itself as a safe, fast replacement for the deprecated Google Image Charts service and supports the same chart types and parameter syntax. The API is essentially two endpoints: a /chart renderer that returns a PNG or SVG and a chart.js renderer that accepts Chart.js v2 configurations. It targets emails, dashboards, and PDFs that need an image of a chart rather than an interactive widget.

## For AI agents

Render charts as PNG or SVG images by calling a single URL with chart type, data, and styling parameters - works in emails and PDFs.

## Scope

Does not handle interactive charting, data warehousing, or dashboard hosting - use for static chart image rendering via URL only.

## Capabilities

- Render bar, line, pie, radar, and other chart types as PNG or SVG via query parameters
- Embed chart images in transactional emails where JavaScript is not allowed
- Drop in as a replacement for legacy Google Image Charts URLs with the same parameter syntax
- Render Chart.js 2.8.0 configurations server-side and return the resulting image
- Generate sparkline-style images for dashboards rendered to PDF

## Use cases

### Charts in Transactional Emails

Email clients block JavaScript, so interactive charts cannot run inline. Image-Charts solves this by rendering the chart as a PNG behind a URL that goes straight into an <img> tag. Marketing and product teams use it for weekly summary emails, billing reports, and onboarding nudges that include data visualisations.

Example prompt: Build a /chart URL with cht=bvg, chd=t:10,20,30, and chs=600x400, then put it in an <img src> tag inside the email template.

### Google Image Charts Migration

Google deprecated Image Charts but many legacy systems still build chart URLs with its parameter syntax. Image-Charts re-implements the same surface, so swapping the host in existing URLs restores chart rendering without rewriting the parameter builder. This is a low-risk fix for old reporting pipelines.

Example prompt: Replace https://chart.googleapis.com/chart in existing URLs with https://image-charts.com/chart and verify the rendered image matches the expected output.

### Server-Rendered Chart.js for PDFs

PDF generation pipelines that use headless Chrome can be slow when many charts are rendered per document. Calling `/chart.js/2.8.0` with a Chart.js config returns a ready-made image, removing the headless render step. Document services use this to keep PDF generation under per-job time budgets.

Example prompt: Send a Chart.js config as a query parameter to `/chart.js/2.8.0` and embed the returned PNG into the PDF template.

### Agent-Generated Chart Embeds

An AI agent producing a Slack or email summary can include a chart by asking Jentic for the Image-Charts URL builder, supplying the data and chart type, and embedding the resulting URL in the message. Because the API requires no auth, Jentic returns the operation schema and the agent calls it directly without any credential handling.

Example prompt: Search Jentic for 'render a bar chart as a PNG', execute the /chart operation with cht, chd, and chs, and place the returned URL in the agent's reply.

## Key endpoints

| Method | Path | Description |
| --- | --- | --- |
| GET | `/chart` | Render a chart as a PNG or SVG image |
| GET | `/chart.js/2.8.0` | Render a Chart.js v2.8.0 configuration as an image |

## Key resources

- **Chart Renderer** — Render a chart as PNG or SVG using URL query parameters.
- **Chart.js Renderer** — Render a Chart.js v2.8.0 configuration as a server-side image.

## Why Jentic

- **Setup:** Wiring Image-Charts by hand means building the chart query string against the image-charts.com host and encoding the chart type, data, and size yourself. Through Jentic you install once, import Image-Charts from the API Directory, and your agent calls it with no key to manage on the public endpoints.
- **Permission scoping:** The public Image-Charts endpoints take all chart settings in the request rather than in path resource ids, so scope the agent to the operations it needs, such as rendering a chart image. Because you choose the allowed operations, the agent is limited to the rendering calls you have named.
- **Credential handling:** Image-Charts has no required credential on its public endpoints, so there is nothing to store. If a signing key is added later, your own Jentic One instance would store it encrypted and inject it at execution time so it never enters the agent's prompt, logs, or context.
- **Discovery method:** Agents search Jentic by intent such as 'render a bar chart as a PNG', and Jentic returns the /chart or /chart.js operation with its parameter schema so the agent calls the right endpoint without browsing the reference docs.

## Related APIs

- **QuickChart** — QuickChart is another URL-based chart image generator that supports Chart.js configurations.
- **Cloudinary Upload API** — Cloudinary delivers images via CDN with transformation parameters.
- **Bannerbear** — Bannerbear renders templated images including data visuals from JSON input.

## FAQ

### What authentication does the Image-Charts API use?

The two public endpoints do not require authentication. Image-Charts offers paid plans that issue a signing key for higher rate limits, but the OpenAPI spec exposed here covers the unauthenticated /chart and `/chart.js/2.8.0` surface.

### Can I render Chart.js configurations as images with this API?

Yes. GET `/chart.js/2.8.0` accepts a Chart.js v2.8.0 configuration and returns a server-rendered image. Use it when a PDF or email pipeline needs a chart image without running headless Chrome.

### Is Image-Charts a true replacement for Google Image Charts?

Image-Charts re-implements the Google Image Charts URL parameter syntax (cht, chd, chs, etc.) on /chart, so replacing the host in existing URLs restores rendering for most chart types.

### How do I render a chart through Jentic?

Run pip install jentic, search for 'render a bar chart as a PNG with Image-Charts', load the /chart operation schema, and execute with the chart type, data, and size parameters. The returned URL can be embedded directly in HTML or markdown.

### Is the Image-Charts API free?

There is a free tier for low-volume use. Higher request volumes and watermark removal require a paid plan from image-charts.com - the OpenAPI spec itself does not cover billing.

### Can I limit what my agent is allowed to do with the Image-Charts API?

Yes. Jentic One is self-hosted by you, so your own rules decide which Image-Charts operations the agent may call, and you can allow just the chart-image rendering it needs, such as the GET /chart renderer while excluding the GET `/chart.js/2.8.0` endpoint. Because every chart setting travels in the request rather than in a path resource id, scoping is done at the operation level: the agent is restricted to the exact rendering calls you have named. The public endpoints require no credential, so there is nothing for the agent to hold, and it can only invoke the operations you have permitted.