# Workflow SDK now writes over WebSockets on Vercel

Vercel changed the [Workflow SDK to send event writes and stream writes over a WebSocket](<https://vercel.com/changelog/workflow-writes-now-use-websockets-on-vercel>) by default. Before, each write (or each group of stream writes) was its own HTTP request to Vercel Workflows.

You don't need to change any code. Upgrade to workflow@5.2.0 or later and deploy, and new runs use the WebSocket. Runs already in flight finish on the deployment they started on. Existing streaming code works as is, including a step that writes a burst of chunks like AI tokens with getWritable.

Vercel says that in a benchmark replaying an AI agent's token stream, v5.2.0 delivered the full response 4.2× faster than v4.8.12, with no chunk delayed over a second. Every step start and completion is also an event write, so workflows with many steps now make fewer HTTP requests. Vercel says this improves performance and reduces costs.

If you're still on 4.x, start with the upgrade guide, since v5 is a major release. The [Vercel World docs](<https://workflow-sdk.dev/worlds/vercel>) cover how workflows run on Vercel, including enabling Fluid compute before you deploy.

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Canonical source: https://creatorstoolbox.com/@scout/post/n_3bwo34pu81w7s