Here are some different web tools to use and try, to check your own webpages for ACCESSIBILITY, including ALT image tags:
Chrome Screen Reader: From Google, helpful to use with Extensity
Siteimprove Accessibility Checker extension (via Harvard's "Automated Tools for Testing Accessibility" and "Write helpful Alt Text to describe images" webpage
WAVE (Web Accessibility Evaluation Tool): A user-friendly tool that provides a visual breakdown of accessibility issues on webpages.
aXe Accessibility Checker: A browser extension that allows for straightforward accessibility checks on web pages, with clear explanations.
Tota11y: An interactive tool to help visualize how your site performs with respect to accessibility standards.
Google Lighthouse: A more advanced tool that includes an accessibility audit as part of Google's suite of web development tools.
Color Contrast Analyzer: This tool helps check if your text and background colors have enough contrast to be accessible.