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Synchronize a cookie into requests ​

Use cookie synchronization when a request header must follow the current value of a browser cookie. Cookie sync is a convenience wrapper around a Modify request header action using the append operation: Headerly supplies the current local cookie value instead of requiring a fixed header value.

Sensitive access

This feature requests the optional cookies permission. Cookie values can contain sessions and credentials. Keep the target conditions narrow so the copied value is appended only to intended requests.

  1. Select a modifyHeaders profile.
  2. Add Cookie sync to request header.
  3. Grant the Cookies permission when prompted. (Your browser may grant it automatically; if no permission prompt appears, skip this step.)
  4. Enter the source domain or paste a URL from that domain. Make sure the resulting Domain exactly matches the Domain column in Developer Tools > Application > Cookies. Preserve any leading dot: if DevTools shows .example.com, do not enter example.com without the dot.
  5. Select the exact cookie, including its domain and path.
  6. Add conditions that identify only the requests that should receive it.
  7. Send a target request and inspect its Cookie request header.

Headerly appends the selected cookie as name=value. When the source cookie changes, Headerly updates the stored value. A missing, deleted, expired, or empty cookie is not appended.

Reuse the profile on another computer ​

For security, Headerly does not include synchronized Cookie values in exported JSON, downloaded profiles, or share links. It exports the Cookie identity—Domain, Path, and Name—with an empty Value.

After another user imports the profile and grants Cookie access, Headerly uses that identity to find the matching Cookie in their browser and synchronizes their local value. This lets multiple users reuse the same profile configuration without transferring Cookie credentials. The matching Cookie must already exist locally, and its Domain, Path, and Name must match exactly.

Use a normal request-header modification when the value should remain fixed. See Synchronize cookies reference for identity and partitioning limitations.