An accessibility scan is an automated check that reviews one or more web pages against WCAG success criteria. You enter a URL, select your conformance level, and the scan evaluates the page’s HTML, CSS, and ARIA attributes for accessibility issues. Results come back in seconds.
| Key Point | What It Means for You |
|---|---|
| What Scans Detect | Automated scans flag approximately 25% of accessibility issues, including color contrast, missing form labels, and structural markup errors. |
| What Scans Miss | Scans cannot evaluate keyboard navigation flow, screen reader experience, cognitive clarity, or whether alt text is actually meaningful. These require manual testing. |
| WCAG Conformance Levels | You can scan against Level A, AA, or AAA. Most organizations target Level AA for ADA and EAA compliance. |
| Monitoring | Scheduled scans (daily, weekly, monthly, or custom) let you track accessibility over time and catch regressions before they accumulate. |
| Authenticated Pages | Pages behind login screens require special tools to scan. Browser extensions make it possible to scan authenticated content without exposing credentials. |
Table of Contents
How Does an Accessibility Scan Work?
An accessibility scan works by loading one or more web pages and running a set of automated checks against WCAG success criteria. The scan evaluates the HTML, CSS, and ARIA attributes on each page and returns a list of issues organized by type.
Each issue maps to a specific WCAG success criterion. For example, a color contrast failure maps to WCAG 1.4.3. The scan results typically show the total number of unique issue types found and the total occurrences across all pages.
From there, you can drill into each issue type to see the individual occurrences, the applicable code, and what is needed to make the fix. Good scanning tools also provide scoring to help you prioritize which issues to address first based on user impact and risk factor.
What Can Scans Detect?
Automated scans are effective at detecting issues that follow clear, testable rules in the code. These include:
- Insufficient color contrast between text and background
- Missing alternative text on images
- Empty or missing form labels
- Improper heading hierarchy
- Missing document language attribute
- Duplicate or missing page titles
- ARIA attribute errors
These are all issues that software can evaluate by reading the DOM. The rules are binary: a color contrast ratio either meets the WCAG threshold or it does not.
What Do Scans Miss?
Scans only flag approximately 25% of accessibility issues. This is a critical point. The remaining 75% require manual evaluation by a person who understands assistive technology and user experience.
Scans cannot tell you whether a screen reader user can actually navigate your checkout flow. They cannot assess whether your alt text is descriptive or just present. They cannot determine if your custom JavaScript widget is operable with a keyboard alone.
This is why an accessibility audit involves multiple diverse evaluation methodologies, and those methodologies are manual. A scan is a review component of an audit. It is not the audit itself.
How Should You Prioritize Scan Results?
Not all flagged issues carry the same weight. Prioritization should account for user impact and compliance risk.
User impact scoring estimates how severely an issue affects people using assistive technology. A missing form label on a login page has a higher user impact than a color contrast issue on a decorative footer element. Risk factor scoring considers how likely the issue is to create legal or compliance exposure under ADA or EAA requirements.
The Accessibility Tracker platform includes built-in prioritization formulas that calculate user impact and risk factor scores for every flagged issue. These scores carry directly into your project workflow, so your team knows exactly where to focus remediation effort on the dashboard.
What Is Accessibility Monitoring?
Monitoring is the practice of running scans on a recurring schedule. Rather than scanning once and moving on, monitoring lets you track your accessibility posture over time.
You can schedule scans to run daily, weekly, monthly, or on custom days. This is especially useful after a site redesign, a CMS update, or any deployment that touches the front end. New code can introduce regressions, and monitoring catches those before they accumulate.
Inside the Accessibility Tracker platform, monitoring is part of the scan feature. If you have a paid plan, you already have access to both scanning and monitoring. Additional scan credits are available through the add-on marketplace for organizations that need higher volume.
What About Scanning Authenticated Pages?
A common limitation of scanning tools is that they cannot access pages behind a login. This means dashboards, account settings, internal portals, and any content that requires authentication often goes unscanned.
This is a significant gap. Authenticated pages are where users interact with your product most frequently. A Chrome extension that runs within an active browser session makes it possible to scan these pages without exposing credentials to a third-party server. Accessible.org is developing this capability, and it will be available soon as part of the Accessibility Tracker platform.
How Do Scans Fit into a Compliance Strategy?
Scans are one tool in a broader compliance strategy. They are fast, repeatable, and good at catching the low-hanging issues that software can identify. But compliance with ADA, EAA, or WCAG requires more than automation.
A complete audit includes manual keyboard testing, screen reader testing, cognitive evaluation, and review of content against all applicable WCAG success criteria. Scanning and monitoring support this process by keeping track of the issues that can be detected automatically, freeing up your audit team to focus on the manual evaluation that only humans can do.
The Tracker platform brings scanning, monitoring, audit tracking, scoring, and workflow management together in one dashboard. Tracker AI assists with documentation and reporting. The goal is a single platform where your entire accessibility project lives, from the initial scan through remediation and ongoing compliance monitoring.
Frequently Asked Questions
How many accessibility issues can a scan detect?
Automated scans flag approximately 25% of accessibility issues. The remaining issues require manual testing with assistive technology and human evaluation against WCAG success criteria.
What is the difference between a scan and an audit?
A scan is an automated check against a set of testable rules. An audit is a comprehensive evaluation that includes manual keyboard testing, screen reader testing, and review against all applicable WCAG criteria. A scan is one component of an audit.
Can I scan pages that require a login?
Standard scanning tools cannot access authenticated pages. A browser extension running within an active session can scan these pages. This feature is coming soon to Accessibility Tracker.
How often should I run accessibility scans?
At minimum, run a scan after every significant deployment or content update. For ongoing compliance monitoring, a weekly or monthly schedule is typical. Organizations with frequent releases may benefit from daily scans.
Do I need a separate subscription for scanning?
If you have a paid plan on the Accessibility Tracker platform, scanning and monitoring are included. Additional scan credits can be purchased in the add-on marketplace.
