Free scanners are real. Here's when you actually need an API instead.
WAVE, the axe DevTools browser extension, and Google Lighthouse are genuinely good, free tools -WAVE andaxe DevToolsare what we'd point a single person checking their own single site toward, too. They're not what this page is trying to talk you out of. They solve a different problem than 3Stone Shield API does.
The actual difference
Free scanners are tools a person runs by hand, one page at a time, in a browser. 3Stone Shield API is infrastructure a program calls - unattended, on a schedule, across as many URLs as your own code sends it. Same underlying engine, in fact: axe-core, the open-source library Deque built and Lighthouse itself uses, is what both approaches are built on. The difference was never the scan quality. It's whether a human has to be the one clicking "scan."
| What you need | Free browser tools | 3Stone Shield API |
|---|---|---|
| Scan one page you're looking at right now | Yes - built for exactly this | Overkill for this use case |
| Scan 50 client sites on a schedule, unattended | No - someone has to click it, every time, on every site | Yes - it's a POST request in a cron job |
| Check every page a user publishes in your app, automatically | No - there's nothing to call from your own code | Yes - built for exactly this |
| Get a plain-language, prioritized report your client can read | No - raw technical violation list | Yes - AI-generated, included in every call |
| Integrate results into your own dashboard or CI pipeline | No - output is for a human, not a program | Yes - structured JSON |
| Cost for one person checking their own one site occasionally | $0 | Not the right fit - use a free tool |
If you recognize yourself here, the API is the right tool
You run an agency
You audit accessibility for multiple clients. Clicking a browser extension per client, per page, doesn't scale - and your client wants a report they can actually read, not a raw rule dump.
You build a platform others publish on
A website builder, CMS, or page generator where every new page a user creates should get checked automatically - there's no human in that loop to run a browser tool.
You build compliance or legal-tech tooling
You need real, grounded scan data feeding your own product's features - not a static checklist, and not something you have to build and maintain the scanning engine for yourself.
If none of that is you - if you just want to check your own one site right now - honestly, useWAVE or theaxe DevTools extension. They're free, and they're the right tool for that job. Or tryour own free hosted scan for a one-off check with an emailed report.
Ready to integrate it?
Real axe-core scanning, an AI-generated report bundled at no extra cost, $49/month for 500 calls.