WAVE, built and maintained by WebAIM, evaluates a live web page and injects color-coded icons directly onto the rendered page to mark errors, contrast issues, ARIA usage, and structural elements like headings and landmarks, letting a reviewer see problems in the actual visual context where they occur rather than in a separate report.
It is available as a browser extension and as a standalone web-based tool, and its visual, in-context approach makes it a popular starting point for developers and content editors who are new to accessibility testing and want to see issues where they actually live on the page.