Why not default domain to the current tab?

This page has no current tab. The extension Import still uses the domains in the file; it does not rewrite them to the active origin automatically.

Should I use example.com or .example.com?

A leading dot (and hostOnly: false) shares the cookie with subdomains. Host-only cookies omit the Domain attribute in the browser and should stay without a leading dot plus hostOnly: true.

Will Netscape export still say localhost if I forget to edit?

Yes. curl will send those cookies only to localhost. That is why the warning exists.

Fix Cookie Domain Defaulted to localhost

Fix “Cookie missing domain, defaulted to localhost”

Cookie missing domain, defaulted to localhost (and the header variant Header string format has no domain info; defaulted to localhost) means the source format cannot carry a host. Paste the header below, then edit domain in the JSON output before you import.

Importing unchanged writes cookies for localhost. They will not be sent to example.com.

Cookie missing domaindefaulted to localhostcookie domain localhostHeader string no domain

1
Paste the header or map
You will see the localhost warning. That is the detector working, not a crash.
2
Rewrite domains in JSON
Output is JSON Array. Change "domain": "localhost" to the API host, with a leading dot if subdomains should receive the cookie. Set hostOnly accordingly.
3
Import on that origin
Open the matching site in Chrome, CookieMan Import, Apply. Or export Netscape after the domain edit for curl.

Paste a Cookie header or JSON map

Output format

Output

Cookies are credentials. Conversion stays in this page — delete the file when you are done.

Message → cause → fix

Message	Cause	Fix
`Header string format has no domain info; defaulted to localhost`	Cookie request header	Edit `domain` in JSON; prefer Set-Cookie if you have it
`Cookie "name" from map has no domain, defaulted to localhost`	JSON map of strings	Use JSON Array from CookieMan instead of a map
`Cookie "name" missing domain, defaulted to localhost`	JSON object without `domain`	Add `domain` on the object

The converter will not guess example.com. Guessing would write cookies onto the wrong host. The warning is the product behaving correctly.

Minimal JSON after you fix the host

            [
  {
    "name": "session_id",
    "value": "abc123",
    "domain": ".example.com",
    "path": "/",
    "hostOnly": false,
    "secure": true,
    "httpOnly": true,
    "sameSite": "lax"
  }
]

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