Limiting document size

[GuiLeme]

The Problem

This is not an immediate bug, but rather a potential limitation that could lead to abuse scenarios.

Since BlockNote runs entirely on the front-end, a malicious user could paste a very large block of text (for example, 3MB of plain text) multiple times into the editor. In collaborative scenarios, this could
result in:

• Significant memory consumption in the browser
• Performance degradation (UI freezing or lag)
• Increased bandwidth usage when paired with real-time collaboration backends
• Poor user experience for participants with limited resources

Even in non-collaborative scenarios, extremely large documents can negatively impact rendering performance and responsiveness.

Currently, there does not appear to be a built-in mechanism to limit the maximum document size. (As far as my research went)

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Proposed Solution

It would be helpful if BlockNote provided a configurable maximum
document size option.

For example:

const editor = useCreateBlockNote({
  maxDocumentSize: 3 * 1024 * 1024, // 3 MB, for example
})

If the document exceeds this limit, BlockNote could:

• Prevent additional input
• Trigger a validation error callback
• Emit an event so the integrator can decide how to handle it

Since BlockNote is a front-end editor, this kind of safeguard would primarily serve as a client-side protection mechanism. Server-side validation would still be the responsibility of the backend.

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Additional Context

I am currently integrating BlockNote with BigBlueButton as a real-time collaboration tool and evaluating potential abuse scenarios involving very large document payloads. A configurable document size limit would help mitigate these risks at the editor level. The integration PR is here in case you need to check on anything.