Check Engine pricing
One price, paid once. No subscription, no page meter, nothing to cancel.
$59once
For Macs with Apple silicon or Intel, macOS 12 or later, and 64-bit Windows
Priced in US dollars. Checkout shows your currency and any local tax.
On a Mac? Get the Mac version.
Launch price: $29.50 once, through 30 November. From 1 December: $59. Buy applies the code FOUNDINGDOCKET for you; if the checkout shows $59, enter it under ‘Have a discount code?’.
Screaming Frog is $279 a year. Ahrefs plans with Site Audit run $129–$449 a month. Check Engine is $59 once. Screaming Frog’s price read 4 November 2026, Ahrefs’ 9 November 2026.
30 days, no conditions, no questions asked. Refund policy
All three apps, Check Engine SEO, Crisp and Outlier, for $49.50 once: the launch price, through 30 November. From 1 December it is $99.
$137 bought apart, $99 together. Launch price through 30 November: $68.50 bought apart, $49.50 together.
Bought it already? Get the 22.5 MB Mac download or the 18.1 MB Windows installer and paste the key from your receipt.
What $59 gets you
- A Check Engine licence for life, in US dollars, with no renewal date. Use it on up to 3 computers at a time, Mac or Windows, and move it by deactivating one.
- No limit on sites. Audit your own, a client's or a prospect's, as often as you want, and bill clients for the work. Nothing is counted per page or per site.
- Every 1.x release, delivered by the updater inside the app. If a 2.0 ever costs money, the version you bought keeps running.
- The key by email, on the receipt. No account to sign up for, and no telemetry.
How paying works
The checkout belongs to Dodo Payments, the reseller and merchant of record for the sale. The Launch price of $29.50 is paid at once: the checkout offers no instalments on a total under $50.01. From 1 December, at $59, you can pay the whole amount at once, or split it with Klarna or Afterpay into four instalments of $14.75 a fortnight apart, at no extra charge from us. Once the fourth is paid, nothing further is ever taken.
If Check Engine turns out not to suit you
Within 30 days of the receipt date, write to the support address or reply to the receipt and you get every cent back, to whatever you paid with. There are no conditions and no form. The refund revokes the key, so within roughly a day the app goes back to the free version.
What is free
Free: your score, how many problems in each category, and the top problem in full with its fix. Pro: the rest of the problems, the ranked fix plan and the markup to paste. The free version needs no key and no account and runs the same full audit, so you can see how much is wrong on your site, and the worst of it, before you pay for the rest.
Before you buy: what it runs on
A Mac with Apple silicon or Intel, on macOS 12 or later, or a PC with 64-bit Windows. If you are unsure, open the full sample report first; it shows what an audit hands you.
On Windows? Download Check Engine v1.3.159 for Windows (18.1 MB, 64-bit, signed by Kerr & Company LLC). Or get it from Microsoft, the same app through the Microsoft Store.
Writing or making videos about Check Engine?
Kerr & Company, the company that sells Check Engine, runs an affiliate programme that pays a commission on each sale, using a personal code the buyer enters at checkout instead of a tracking link. The rates, the payout terms and the disclosure you owe your readers are on the affiliates page.