How do I embed a financial chart in a Substack post?

What Substack actually supports — and what it doesn't

Let's be upfront: Substack does not support custom iframe embeds or raw HTML. This is a significant limitation that most chart-tool guides gloss over. If you paste an iframe code block into a Substack draft, it simply won't render.

What Substack does support for charts:

• Datawrapper embeds (paste the Datawrapper URL, Substack auto-renders it)

• Substack's native financial chart widget (basic stock/crypto/commodity price charts as static images)

• Polymarket odds embeds

• LaTeX equations

• Uploaded images (PNG, JPEG, GIF)

That's the complete list. No TradingView iframes (despite what some guides suggest — Substack's native widget is not the same as an iframe), no custom HTML, no third-party chart widgets unless Substack has specifically allowlisted them.

What this means for finance newsletter writers

If you need charts that go beyond what Datawrapper and Substack's native widget offer — yield curves, volatility surfaces, options chains, FedWatch probability trees, credit spread charts — you have two realistic options:

Option 1: High-quality static image (recommended)

Create your chart in a tool like Quadesto, export as a high-resolution PNG (2x or 3x for retina displays), and upload it as an image in your Substack post. This is how most professional finance newsletters handle complex charts.

The key is making the static image look publication-ready: correct axis labels, readable fonts, branded colours, and a clear title. Quadesto exports at up to 3x resolution specifically for this use case.

Add a caption below the image with a link: 'View interactive version →' pointing to the chart's public Quadesto URL. Engaged readers click through to explore the data; everyone else gets the visual.

Option 2: Datawrapper for basic charts

Datawrapper's free tier is excellent for bar charts, line charts, and scatter plots. If your chart is general-purpose (no finance-specific chart types needed), Datawrapper plus Substack works well.

Limitation: Datawrapper doesn't support candlestick charts, volatility surfaces, yield curves, options chain tables, or any chart type that requires financial methodology. For those, you need Option 1.

The practical workflow for Substack finance newsletters

Here's the workflow we recommend for Substack writers who need finance-specific charts:

1. Create your chart in Quadesto (upload data, AI builds the visualization)

2. Refine via chat if needed ('add Bollinger Bands', 'show only 2024 data')

3. Export as PNG at 2x resolution (retina-quality)

4. Upload the PNG in your Substack draft

5. Add a caption: 'Interactive version at quadesto.com/view/[id]'

This gives your readers a beautiful, finance-correct chart in their email and inbox, with the option to explore interactively if they want.

Where iframe embeds DO work

If you're on a platform that supports iframes, Quadesto charts embed interactively with one line of code:

• Ghost — supports raw HTML via the HTML card. Full interactivity.

• Beehiiv — supports iframes via the HTML content block.

• WordPress — supports iframe embeds natively.

• Webflow — supports the Embed element.

• Notion — supports /embed with any URL.

• Any custom website — paste the iframe code.

If you're evaluating newsletter platforms and interactive chart embeds matter to your workflow, Ghost and Beehiiv are more permissive than Substack for this specific use case.

Why we're being honest about this

Many chart tools imply universal embed support without mentioning platform limitations. We'd rather tell you exactly what works where, so you can make the right choice for your workflow. The Substack limitation is real, but the static-image workaround produces genuinely beautiful results — and the interactive link gives your most engaged readers the full experience.