OneFreePlace
FREE ONLINE TOOL

Free CORS Header
Builder

Validate an exact origin against an allowlist before echoing it back.

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FreeUse this tool without paying.No sign upStart with the tool right away.Clear stepsRead the tool’s own guidance.

About Free CORS Header Builder

Design a least-privilege CORS policy, simulate real origins and preflight requests, catch wildcard/credential mistakes, and generate server code that validates origins instead of blindly reflecting them.

Workspace options

  • Origin strategy
  • Allow credentials
  • Allowed origins · one per line
  • GET
  • HEAD
  • POST

Available actions

  • Builder
  • Simulator
  • Server code
  • Guide
  • Public API
  • Credentialed app