demo · v143

FedCM Migration Wizard

A 4-step tool that scans your existing credentials.get() call for deprecated FedCM patterns, shows a before/after diff, outputs migrated code, and optionally fires the new API in-browser to verify it.

1Scan code

2Review changes

3Apply

4Verify

Step 1 — Scan your FedCM code

Paste your existing navigator.credentials.get() call. The wizard detects old patterns: nonce at the top level instead of inside params, and legacy IdentityCredentialError code values.

// Paste your credentials.get() call here, or pick a preset above

Step 2 — Review changes

The diff below shows every change needed. Lines in amber are the old patterns that need updating.

Before (original)

After (migrated)

Step 3 — Migrated code

This is your code after applying all migrations. Copy it and replace the original in your codebase.

Step 4 — Verify in browser

Fires the migrated navigator.credentials.get() call in this page. Since no real IdP is configured, the browser will reject it — but a proper FedCM error (not a parameter error) means the new format is accepted.

What to expect: Chrome will return an error because there is no real identity provider here. A result like NetworkError or NotAllowedError means the API accepted the new parameter shape and reached the network stage. A TypeError: Invalid params would mean a format problem.

Output will appear here…

What changed in Chrome 143

nonce moved — previously nonce was a top-level field inside the identity provider object. In Chrome 143 it must be nested inside params: providers: [{ configURL, clientId, params: { nonce } }].
Error code renames — IdentityCredentialError code values were renamed for clarity: "account_hint_mismatch" → "hint_mismatch", "request_not_supported" → "not_supported", "idp_not_allowed_by_rp" → "not_allowed".