Automated vs. manual accessibility audit
Updated October 25, 2026 · The ScanMeridian Team
An automated accessibility audit uses software to check web pages against the WCAG rules that a tool can test, such as missing alt text, low color contrast and unlabeled form fields. A manual audit is done by a person with a keyboard and a screen reader. Automated audits are fast and repeatable. Manual audits find what software can't judge.
What an automated audit checks
An automated audit opens each page in a browser and runs a set of rules against the code. Our scanner uses axe-core 4.14, an open source rules engine, with the rules for WCAG 2.1 Level A and AA. Typical findings:
- Images, icons and image buttons with no text alternative.
- Text whose color contrast with its background is below 4.5:1 (3:1 for large text).
- Form fields with no label, and buttons or links with no name.
- A page with no title, or no language set.
- Screen reader attributes (ARIA) used in a way that doesn't work.
These checks are objective: the code either has the label or it doesn't. That is why a tool can run them quickly on many pages, and run them again after each fix.
What only a person can check
Many WCAG requirements need judgment. Software can see that something exists, but not whether it works for people:
- Whether an image's alt text actually describes the image, or just says "image".
- Whether a keyboard user can reach every control, in a sensible order, and see where the focus is.
- Whether a screen reader user can complete a task, such as booking a table or paying.
- Whether error messages explain what went wrong and how to fix it.
- Whether captions match what is said in a video.
In a 2017 test by the UK Government Digital Service, 10 automated tools were run on a page with 143 known barriers. Together they found 71% of them, the best single tool found 41%, and 29% were missed by every tool. Read the GDS report. Tools have improved since, but the lesson holds: an automated scan finds only some issues.
Side by side
| Automated audit | Manual audit | |
|---|---|---|
| Who does it | Software (a rules engine) | A person, often with a screen reader |
| What it finds | Issues a rule can detect in the code | Issues that need judgment, plus many a tool also finds |
| Speed | Minutes for many pages | Hours or days, depending on the site |
| Repeating it | Easy, the same rules every time | Takes the same effort each time |
| Pricing | Usually per site or per set of pages | Usually by pages and hours of testing |
| Best for | A first pass, and checking fixes | Key tasks like checkout or sign-up, before a launch |
When to use which
Start with an automated audit. It gives you a list of concrete fixes your developer can make right away, and you can run it again to confirm the fixes. Then have a person test the tasks that matter most to your customers, such as finding a product, filling in a form and paying. If you can only do one thing this month, fix what the automated audit finds, and test your checkout with a keyboard yourself.
Where ScanMeridian fits
ScanMeridian is an automated audit. The Free Snapshot ($0) checks your homepage. The Automated Report ($249) checks up to 25 public pages and explains each issue, who it affects and how to fix it. It does not include manual or screen reader testing, and it finds only some issues. See the WCAG 2.1 AA checklist for which criteria our rules cover.
A note on the ADA
The Americans with Disabilities Act is a U.S. civil rights law. For most private businesses it does not name a technical standard for websites, and the Department of Justice has pointed to WCAG as helpful guidance. Neither an automated nor a manual audit is a legal opinion or a certification. For legal questions, talk to a qualified lawyer.