During the review phase of a website migration that involved decades of content and a complex URL structure, which meant going through the site page-by-page checking for content and formatting that was missed or mangled in the migration, I made two simple bookmarklets: Go to this page on old {{client_name}} site and Go to this page on new {{client_name}} site.

They didn’t replace side-by-side comparison and automated diffs, but I found these bookmarklets surprisingly useful for quickly tabbing to the same page on the other version of the site any time I noticed something anomalous.

The code was ridiculously simple:

javascript:void function(){javascript:(function(){window.location=window.location.toString().replace(/www.oldsite.com/,"www.newsite.com")})()}();

Here is a hand-coded interactive widget, if you’d like to make your own old site, new site bookmarklets for a migration:

Put the URLs of the old site, and the new/staging site, into the two inputs above. (Skip the protocol, but include the subdomain if there is one.) Then, drag the gaudy bookmarklet buttons to your bookmarks bar.