If your job is link rows in a script, per-call pricing wins by a wide margin. If your job is keywords, rankings and daily crawl data, a Semrush or Ahrefs seat does things this API never will. The comparison is not apples to apples, so read the gaps table before you cancel anything.
Ahrefs API: from $129 a month for 200,000 units, at least 50 units per request
That ceiling works out to 4,000 requests a month at the minimum charge
$129 of credit here buys 1,290,000 credits, or 645,000 two-credit calls
Nothing expires monthly and there is no minimum spend
Cheap habits
Start with the free actions to confirm a domain is in the index
Batch with bulk_dr: 2,000 domains for one credit
Read lists at per=1000, because the price does not change with rows
Save responses to files instead of calling twice
Set a calendar reminder for the monthly refresh, not a daily cron
What the $100 free credit covers
Sign-up gives 1,000,000 credits and asks for no card. That is a million bulk_dr calls, or 500,000 backlinks pulls, or 333,333 search calls.
A worked example, clearly hypothetical. You track 300 donor domains. One bulk_dr call per week is 4 credits a month, about $0.0004, and a 2-credit backlinks pull on your own site every Monday takes the month to 12 credits, or $0.0012.
Even a sloppy loop that fires a thousand calls by mistake costs ten cents. Pair this with the Sheets tracker and the monthly bill is a rounding error.
Where it stops
Honest gaps against the big suites.
Need
Quicklinky
Ahrefs or Semrush
Backlinks and referring domains
Yes, from our own index
Yes, deeper history
Keyword research and rank tracking
No
Yes
Crawl freshness
Roughly monthly
Fresher, daily in places
Pricing shape
Prepaid, per call
Subscription
Domain strength
Our own DR, 0 to 100
Their own DR or Authority Score
Billing questions
What happens when the credit runs out?
Authenticated calls return HTTP 402 until you top up. Free actions keep working. Top-ups go through USDT (TRC-20) on the account page, so there is no card to expire and nothing renews by itself.
Is there a per-second rate limit?
We do not publish a per-second quota here, and credit balance is the real throttle. Pace big loops sensibly and handle a 402 cleanly. The error table shows what each status means.
Do larger row counts cost more?
No. A call is billed once whether it returns 10 rows or 1,000. That makes per=1000 the cheapest way to read a big list, as the competitor pipe does.