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chartjs2img

chartjs2img

Chart.js charts, rendered anywhere.

Get startedUse with AI agentsView on GitHub
01-bar-chart03-line-chart05-pie-chart07-radar-chart10-bubble-chart11-mixed-chart-bar-line13-bar-with-data-labels14-line-with-annotation15-treemap-chart18-japanese-labels01-bar-chart03-line-chart05-pie-chart07-radar-chart10-bubble-chart11-mixed-chart-bar-line13-bar-with-data-labels14-line-with-annotation15-treemap-chart18-japanese-labels

One JSON, two destinations

Chart.js renders the same configuration in a browser for an interactive chart. chartjs2img takes that same JSON and returns a PNG you can attach to Slack, an email, or a PDF report — no browser required on the receiving side.

Diagram — Chart.js JSON branches into two flows. Top path goes into Chart.js and renders live inside a browser. Bottom path goes into chartjs2img which produces a PNG, then the PNG is attached to Slack and email.

Chart.js + 12 plugins bundled

Core plus datalabels, annotation, zoom, gradient, treemap, matrix, sankey, wordcloud, geo, graph, venn, and the date-fns adapter. No extra installation.

HTTP API + CLI

POST JSON, get an image back. Or pipe JSON into the CLI and redirect to a file. Same engine, cache, and plugin bundle.

Hash-based caching

Identical requests return cached images instantly. SHA-256 hashes travel in headers so clients can build CDN-friendly URLs.

LLM-native

`chartjs2img llm` dumps the full Chart.js + plugin reference as Markdown. Pipe it into an agent to get valid configs first try.

JSON in, image out

Send any Chart.js configuration as JSON; chartjs2img returns the rendered PNG. Left is the exact output of the config on the right.

Chart.js configuration (JSON)
…
Rendered PNG (800 × 600)
bar-chart
Showcase

Complex charts render, too

Multi-plugin composites — time axes, annotations, data labels, stacked and dual-axis layouts — all from a single JSON request.

showcase-revenue-with-forecast

Revenue with forecast band

Time-series line + gradient stroke, forecast window (annotation), goal threshold, peak-point marker, and on-point data labels.

showcase-ops-dashboard

Ops dashboard snapshot

Stacked-bar ticket backlog with an overlay SLA-breach-rate line on a secondary Y axis, plus threshold line and peak-load window annotations.

AI-native

Built for LLM agents out of the box

Four first-class integration channels — pick whichever host you already use. Every path speaks the same Chart.js JSON shape, so your configs stay portable between agents.

Ready to render?

No signup, no API key — everything runs locally.

Read the guideUse with AI agentsGitHub

Built on open source

chartjs2img stands on the shoulders of these projects. Licenses and notices are reproduced inside the Docker image and the source tree.