What mkt_tok actually is
Marketo, Adobe's marketing automation platform, appends mkt_tok to every link inside a marketing email it sends. The value is generated when Marketo builds that individual copy of the email, before anyone opens it. It is not created by the click.
That timing is the whole story. The token already points at a specific record in the sender's database. Paste a URL containing mkt_tok above and the decoder splits it from the rest of the link, so you can see your real destination without guessing which part of the string is the actual page.
It is tied to a lead record, not a browser
Most parameters on this site identify a click, a session, or a campaign. mkt_tok identifies a person who already has a name and an email address on file in someone's Marketo instance. The token itself is an opaque, encoded string, and it is case-sensitive: change a single character and Marketo will not resolve it back to the right record.
Forwarding an email keeps this token attached. If a marketing email gets forwarded and a colleague clicks the link, the click can still log against the original recipient's lead record, because the same mkt_tok travels with the copy-pasted URL. The person clicking is not the person the click gets credited to.
What changes when it's stripped
Delete mkt_tok and the landing page opens exactly as before. The parameter carries no weight for the page itself.
On Marketo's side, the effect is different. Without the token, the platform has nothing to match the visit to a lead record. It will not show up on that contact's activity timeline, and it will not satisfy any scoring or nurture step built to fire on a link click.
Reading the rest of the link
Marketo links often carry mkt_tok next to standard campaign parameters. If yours also has UTM tags, run it through utm_campaign, or build your own with the UTM builder. Came from a HubSpot email instead? The closest equivalent is _hsenc, HubSpot's own per-contact token.