Mailchimp MD5 email hasher

MD5-hash emails for Mailchimp subscriber_hash in your browser. Lowercase first. Nothing is uploaded.

Algorithm Lowercase and trim Skip duplicates

Paste emails, then Hash list.

How to use the Mailchimp MD5 email hasher

Paste emails or a CSV with an email column.
Hash with MD5. Mailchimp wants lowercase before the digest.
Use each 32-character hex as subscriber_hash in the API path.

subscriber_hash

Mailchimp identifies a list member as MD5 of the lowercase email. That is a lookup key, not encryption. Do not upload this file to Meta or Google as a SHA-256 audience. 32-character hex that is already MD5 is left alone.

Nothing is uploaded

Hashing stays in the browser.

Mailchimp MD5 email hasher FAQ

Same as Gravatar?

Same MD5 of lowercase email. Different product; this page’s copy is for the Marketing API.

HMAC?

Not for subscriber_hash. Leave the algorithm locked to MD5.