A version of your resume written for one specific posting.
The work that actually moves the needle on an application is boring and repetitive: read the posting, work out what they care about, pull the relevant things forward, use their words for the thing you already do. Forty minutes a job, and it is the first thing people stop doing around application fifteen.
This does that part. Your master resume stays exactly as it is; each application gets its own version alongside it.

One saved in your tracker, or one you paste in from anywhere else.
Reordered and reworded to lead with what this employer asks for, using their vocabulary for the things you already did. The master resume is not modified.
Beside the document, not behind a button: the approach taken, what was brought forward, which of their terms now describe your work, and anything left out with the reason it went. If you want something back, "Put it back" returns it. Nothing disappears silently.
The same editor as your master resume, with the same templates, colors and font size. Edits stay with this application and leave your master resume alone.
Written from the posting for the same job and shown as the page it prints on, with notes on what was written and why. Edit it right on the page, date and recipient lines included, or ask for a change (shorter, warmer, more confident, or in your own words) and undo it if you prefer what you had.
These are constraints we chose, not gaps we haven't got to.
Tailoring reorders and rewords freely, removes very little, and reports every removal. Your employment history stays complete.
If a posting lists something as required and it is not on your resume, we say that plainly and suggest adding it if you have it.
Targeted Applications reads from your master resume, so that is where to start.
Build my master resume first