Knowledge base
Automated Scans vs Human Review: What Each One Can Actually Test
Automated scanners are fast, consistent and tireless, and they cannot test everything the standard requires. The W3C, which wrote WCAG, says so directly. Knowing which checks belong to the machine and which take a person is the difference between a useful accessibility program and a false sense of security.
Sources
Key takeaways
- Scanners measure well: contrast ratios, missing alt attributes, unlabeled form fields, invalid accessibility markup, missing page language.
- Scanners cannot judge: whether alt text carries the image's meaning, whether a page makes sense read aloud, whether a keyboard flow is usable.
- Nobody can certify: a certificate from a scanner is worth what the scanner missed. No honest vendor sells one.
- Our split: automation drafts, a person verifies every finding, and a deeper hands-on review is available as an add-on.
What does an automated scan test well?
The checkpoints with a measurable answer. A contrast ratio is arithmetic. A missing alt attribute is a fact. An unlabeled field, a missing page language, a heading jump from H1 to H4: all of it is machine-checkable, repeatable and cheap to run monthly, which is exactly why monitoring is built on it.
In detail
The machine's other strength is coverage. A person cannot re-read ten thousand pages every month; a scanner can, and it never gets bored on page nine thousand. On a site that changes weekly, the scanner is the only realistic way to catch the new PDF, the new form and the regression a theme update caused, month after month, against all 50 required checkpoints that have testable, automatable parts.
Automated scans vs human review: what can only a person judge?
Meaning. A scanner confirms an image has alt text; only a person can say whether the alt text does the same job as the picture. A scanner confirms a form field has a label; only a person can say whether the form makes sense read aloud in order by a screen reader. A scanner confirms every control is keyboard-reachable; only a person can say whether the keyboard order of a payment flow is actually usable.
In detail
The W3C's own guidance on evaluating accessibility is built around this split: automated tools help, and human evaluation is required for checks that involve judgment. That is why every ADA Site Monitor report includes a person verifying the automated findings, and why the deeper pass, a hands-on keyboard and screen-reader review of your highest-traffic pages, is offered as an optional add-on priced for what it is: human hours.
Why does no honest vendor sell a compliance certificate?
Because certifying ADA compliance would mean guaranteeing something no tool can fully test and no outsider controls. The W3C states that automated tools cannot evaluate every requirement. A "certified accessible" badge from a scanner is worth exactly what the scanner missed, and the websites that display one get complaints anyway.
In detail
What an honest vendor can provide is evidence: dated test results, human-verified findings, a record of fixes verified on re-scan, and a documented, continuing effort. That evidence is what our found-and-verified record is, and it is the closest thing to proof this field honestly offers. The positioning is on our main compliance page and in our contracts: we do not sell certificates, because nobody honestly can.