Have you encountered a CORS policy error while trying to call an external API with Webflow Logic? It works fine in the designer, but raises an error when deployed. Any suggestions or solutions for this issue?
TL;DR
- CORS errors occur on live Webflow sites because browser-based API calls require proper CORS headers, unlike server-side calls in Webflow Designer.
- Fix by using a server-side proxy (e.g., Netlify/AWS Lambda), Webflow Logic webhooks, or third-party tools like Zapier that bypass CORS with server-side requests.
CORS policy errors often occur when using Webflow Logic to make external API calls that lack proper CORS headers when the site is deployed. This is a common issue due to browser security policies that restrict cross-origin requests.
1. Understand Why It Works in Designer But Not When Deployed
- In Webflow Designer, API calls are made from Webflow's internal environment (server-side), bypassing CORS policy checks.
- On the published (live) site, the API call is executed client-side (in the user’s browser), which must comply with CORS restrictions enforced by the browser.
2. Check the API's CORS Settings
- Ensure the external API includes the CORS header: Access-Control-Allow-Origin: * or at least allows your Webflow domain.
- If the API does not include appropriate headers, browsers will block the request.
3. Use a Proxy Server
If the API does not support CORS, you need to proxy the request through a server that you control:
- Set up a cloud function (e.g., AWS Lambda, Netlify Functions, Vercel Serverless Function) to act as a proxy.
- The function makes the API call server-side, avoiding CORS issues.
- In Webflow Logic, call this function’s endpoint instead of the original API.
4. Prefer Logic Webhooks Over Frontend Calls
- Webflow Logic allows you to trigger workflows via Webhooks, which run from the server.
- If the data-fetching action can be moved into a Logic flow, use this instead of directly calling the API from client-side JS.
5. Use Tools That Handle CORS Automatically
- If you use third-party integration platforms (like Make, Zapier, or Integromat), they operate server-side and are not affected by CORS policies.
- These tools can fetch the API data and push it to Webflow via Logic or Webhooks.
Summary
CORS errors in Webflow Logic usually happen because the API doesn't allow cross-origin requests in the browser. Use a server-side proxy, Webflow Logic webhooks, or third-party automation tools to avoid client-side CORS issues when deployed.