Changelog

Changes for internal APIs affecting site data sync in the browser

To support real-time collaboration, we’re implementing version control on a set of internal APIs used to read and write site data to the designer from the browser. To ensure continued functionality of browser extensions and tools that currently use this set of APIs, please see the timeline and migration steps below.

Please note: If you’re building apps with Webflow’s official set of Public APIs, this won’t affect your work.

Affected internal endpoints

Starting August 13, 2025, the following internal site data sync endpoints will now support and enforce version control.

• GET /sites/{siteName}/dom
• POST /pages/{pageId}/dom
• POST /sites/{siteName}/variables
• PATCH /sites/{siteName}/variables/{variableId}
• POST /sites/{siteName}/styles

Starting September 15, 2025, these endpoints will require a version number in all write requests. Requests without a version number will return an error.

These endpoints will be fully deprecated and removed in January 2026. We recommend updating your tools now to comply with version checks, while also planning your migration away from these endpoints before the deprecation date.

Timeline

Version management

Reading site data

The GET /sites/{siteName}/dom endpoint now returns version fields for the following resources:

Writing site data

The following endpoints require version numbers in the request body for all writes:

• POST /pages/{pageId}/dom
• POST /sites/{siteName}/variables
• PATCH /sites/{siteName}/variables/{variableId}
• POST /sites/{siteName}/styles

Errors and responses

POST and PATCH requests to the above endpoints will return errors if the version numbers are missing or don’t match.

• 409 Conflict: Version mismatch.
  A later version of the data is available. Fetch the latest data and retry the operation.
• 400 Bad Request: Missing version numbers in write requests.
  The request body must include a version number for each resource in the request.

Migration steps

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const response = await fetch(`/sites/${siteName}/dom`);
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const data = await response.json();
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// Store version numbers for sync
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const versions = {
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  domNodes: data.domNodesVersion,
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  styles: data.stylesVersion,
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  variables: data.variables?.map(v => ({ id: v.id, version: v.version })),
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  variableCollections: data.variableCollections?.map(vc => ({ id: vc.id, version: vc.version }))
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};

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// Example: Updating styles
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const updateResponse = await fetch(`/sites/${siteName}/styles`, {
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  method: 'POST',
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  headers: {
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    'Content-Type': 'application/json; charset=UTF-8',
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    'X-Requested-With': 'XMLHttpRequest',
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    'X-XSRF-Token': 'YOUR TOKEN HERE'  // must match the current from browser cookies
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  },
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  body: JSON.stringify({
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    styles: newStyles,
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    stylesVersion: versions.styles // Include current version
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  }),
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  credentials: 'same-origin'
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});
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if (updateResponse.status === 409) {
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  // Version conflict - fetch latest data and retry
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  const latestData = await fetch(`/sites/${siteName}/dom`);
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  // Update your local versions and retry the operation
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}

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async function updateWithRetry(endpoint, data, maxRetries = 3) {
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  for (let attempt = 0; attempt < maxRetries; attempt++) {
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    try {
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      const response = await fetch(endpoint, {
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        method: 'POST',
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        headers: {
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          'Content-Type': 'application/json; charset=UTF-8',
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          'X-Requested-With': 'XMLHttpRequest',
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          'X-XSRF-Token': 'YOUR TOKEN HERE' // must match the current from browser cookies
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        },
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        body: JSON.stringify(data),
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        credentials: 'same-origin'
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      });
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      if (response.status === 409) {
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        // Fetch latest versions and retry
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        const latest = await fetch(`/sites/${siteName}/dom`);
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        const latestData = await latest.json();
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        data.stylesVersion = latestData.stylesVersion;
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        // Update other version fields as needed
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        continue;
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      }
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      return response;
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    } catch (error) {
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      if (attempt === maxRetries - 1) throw error;
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    }
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  }
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}

Important reminders

• This API will be fully deprecated and removed in January 2026
• Consider migrating to official Webflow APIs when available.
• Test thoroughly in development environments before deploying

Support

For questions about this migration, contact our developer support team. However, we can’t provide ongoing support for private API usage.