Free AASA Checker: Validate Your apple-app-site-association File
Paste your domain below to instantly check whether your apple-app-site-association (AASA) file is set up correctly for iOS Universal Links. Free, no sign-up.
Free to use. No sign-up required.
If your Universal Links aren't opening your app, a misconfigured AASA file is the most common cause — and it usually comes down to a handful of fixable issues. This tool checks your setup so you don't have to dig through Console logs.
What is the apple-app-site-association file?
The apple-app-site-association file is a small JSON file you host on your domain that tells iOS which app should open which URLs. When someone taps a link to your domain, iOS reads this file to decide whether to open your app (a Universal Link) or fall back to Safari. If the file is missing, unreachable, or malformed, iOS silently ignores it and your links open the website instead of your app — with no error message to tell you why.
That silent failure is exactly why a validator is useful: Universal Links either work or quietly don't, and the cause is almost always in the AASA file or how it's served.
What a correct AASA setup requires
For iOS to honor your Universal Links, all of the following need to be true:
- Reachable at the right path — iOS looks for the file at
https://yourdomain.com/.well-known/apple-app-site-association. - Served over HTTPS — with a valid certificate.
- No redirects — the file must be served directly, not via a 301/302.
- Correct content type — served as
application/json, with no file extension on the filename. - Valid JSON — a single syntax error makes the whole file unusable.
- Correct structure — a proper
applinksblock with yourappID(Team ID + Bundle ID) and the URLpaths/componentsyou want handled. - No authentication — the file must be publicly accessible, not behind a login or firewall.
Miss any one of these and Universal Links fail silently.
What this checker tests
Paste your domain above and the checker fetches your AASA file and reports exactly what it finds. No sign-up, no SDK, nothing to install. Specifically, it verifies:
- Reachability — whether your domain responds, and flags timeouts or connection failures.
- File found — that an AASA file exists at
/.well-known/apple-app-site-association(a 404 means iOS has nothing to read). - Served over HTTPS — the file is fetched over a secure connection.
- Valid JSON — the file parses cleanly; a single syntax error is caught.
- Correct structure — a proper
applinks(orwebcredentials) block, and lists the App IDs it finds configured. - Publicly accessible — surfaces auth/firewall responses that would hide the file from iOS.
Why are my Universal Links not working?
The usual culprits, in order of how often they bite:
- 1The AASA file isn't where iOS expects it (wrong path, or only at the root and not under
/.well-known/). - 2It's served with the wrong content type or with a redirect in the way.
- 3A JSON typo breaks parsing.
- 4The
appIDis wrong — a mismatched Team ID or Bundle ID. - 5The Associated Domains entitlement is missing or misspelled in the app (
applinks:yourdomain.com). - 6iOS cached an old version of the file — Universal Links don't always pick up changes instantly.
The checker above catches the server-side issues (1–4). The app-side ones (5–6) you fix in Xcode.
Skip the AASA headache entirely
Hosting the apple-app-site-association file correctly — right path, right headers, no redirects, valid certificate — is fiddly, and it's the part of Universal Links that breaks most often. DeepTap hosts your AASA and Android assetlinks.json files for you, auto-generated and served from a global edge network, so the configuration is correct by default. Zero code, no SDK, no server to maintain — from $5.99/month.
Frequently asked questions
What is an AASA file?
apple-app-site-association is a JSON file hosted on your domain that tells iOS which of your URLs should open your app instead of Safari. It is what makes iOS Universal Links work.
Where should the apple-app-site-association file be hosted?
At https://yourdomain.com/.well-known/apple-app-site-association, served over HTTPS, as application/json, with no redirect and no file extension.
Why isn't my Universal Link opening the app?
Most often the AASA file is unreachable, served with the wrong content type, behind a redirect, or contains a JSON error or wrong app ID. Run the checker above to find which. If the file is fine, check that your app has the Associated Domains entitlement (applinks:yourdomain.com).
Does the AASA file need to be at the root or under /.well-known/?
Modern iOS looks under /.well-known/. Hosting it there is the reliable choice.
Do I need an SDK to use Universal Links?
No. Universal Links are a native iOS feature driven entirely by the AASA file and your app's entitlement. DeepTap hosts the file for you without any SDK in your app.
Is this checker really free?
Yes — no sign-up, no account needed. Paste your domain and check.
Check your AASA file now
Or skip the manual setup: let DeepTap host your deep-link config — correct by default, from $5.99/month.