Use direct competitors that sell the same thing to the same buyers
Leave out giant media sites that link to everyone
Include one rival that is smaller than you, since small sites often show easier links
Save each pull with the date, because the index moves monthly
Never email a donor you have not opened by hand
Reading the output without fooling yourself
Overlap is a hint, not a recipe. A site that links to all three rivals is probably a directory, a roundup or a niche resource. Some of those welcome you. Others are paid slots.
Sort the shared list by DR. Then drop anything you cannot read in two minutes, and open the top ten by hand to see how each rival earned the link: a resource page, an interview or a sponsored post. The DR threshold table helps you skip the weak ones fast.
Before any outreach, rerun the pull next month. The graph refreshes monthly, and a rival's fresh link will appear then, not today.
Keep the pull dates in a note, since the index rebuilds roughly monthly and the picture shifts when it does.
A hypothetical run, with invented numbers
Take this as an example only. You sell trail-running shoes and pick three rivals. The shared list returns 180 domains. After removing the 40 that already link to you, 140 remain.
Sort by DR and keep the 25 above 40. Open each. Maybe 9 are real roundups, 6 are dead directories, and the rest are forums you cannot join. That leaves a short outreach list of 9, from a run that cost 4 credits in total, or $0.0004.
Gap run, start to finish
1
Pick two to ten rivals
intersect takes 2 to 10 domains. Three direct competitors beat ten loose ones.
2
Run the call
Save the JSON to gap.json. Inspect the field names once, then script around them.
3
Subtract your own
Pull your refdomains and remove anything already present.
4
Rank and review
Sort by DR and eyeball the top of the list. Build a short outreach file, not a long one.
Gap questions we hear
Can this replace a paid suite? For a first gap list, often. Ahrefs and Semrush stay fuller for keyword overlap, traffic estimates and daily-fresh data, while the curl route wins when you want the list inside a script for pennies.
How many rivals? Two to five read well. The endpoint accepts up to ten, but overlap shrinks fast as you add names, so start with three and widen only if the list comes back too thin.
What did the run cost? Every authenticated reply carries a _credits field with the cost and your remaining balance, and the curl cheatsheet shows how to read it.