Marriage certificate apostille
Used for spousal visas, foreign name changes, and residency filings for a foreign-born spouse.
What you need
A certified copy from the county auditor where the license was filed, not the decorative keepsake certificate handed out at the ceremony. If you only have the keepsake copy, I can point you to the right county office before anything is submitted.
Where it was issued matters
Washington apostilles only cover marriages recorded in Washington. If you married in another state, that state's Secretary of State has to apostille the certificate — see mail-in service.
Common destinations
Spousal visa applications and foreign residency permits are the most common reasons this document needs an apostille. Some countries also want the certificate translated before it's accepted — worth confirming with the receiving agency ahead of time.