You pointed your app at FlowMock and something's off. Let's walk through the usual suspects before anyone opens a support ticket.

Quick checklist

Is the proxy URL correct? Copy it from the dashboard - don't guess.
Is your session key being sent? Check for x-flowmock-session on proxied requests.
Is the mock on for your session? Published ≠ active, and a draft only applies to the session of the person who made it.
Check the logs tab - did the request even hit FlowMock?
Using the extension? The DevTools FlowMock tab labels every request: Mocked, Transformed, Delayed, or Proxied. No label means the request never reached FlowMock.

App gets staging responses (mocks don't apply)

Session key missing or wrong Open browser devtools → Network → find a proxied request → check headers. You should see x-flowmock-session. If not, your app isn't sending it. (The browser extension sends it for you, unless Follow site identity is on for the site.)

Mock not activated Published mocks sit in the library until you activate them for a session. Check the session strip, or the Active view in the extension's DevTools tab.

Matcher doesn't match Your mock targets GET /api/cart but the app calls GET /api/v2/cart? No match, pass-through to staging. Check the Logs tab for the actual path.

Wrong environment Multi-endpoint projects need the right environment slug. If you have both staging and qa endpoints, make sure you're configuring the one your app hits.

Usually a cookie domain issue. See Cookie auth and Domain verification.

If your app uses Better Auth or an OAuth provider (Google, GitHub), the auth library needs to know about the proxy host too - cross-subdomain cookies, trusted origins, and the OAuth callback URL. The framework notes cover the exact settings.

Quick test: does auth work on the default p.flowmock.dev URL? If yes but custom domain fails, it's DNS. If both fail, cookies might need Secure + HTTPS.

HTTPS / certificate errors

FlowMock handles TLS on custom domains after verification. If you see cert errors:

Domain might not be verified yet
DNS might still be propagating
You might be hitting the wrong host

Requests time out

Global delay - check if your session has a delay configured (intentional slow responses)
Staging is down - FlowMock forwards to staging; if staging is unreachable, you'll see timeouts
Network - corporate VPN or firewall blocking the proxy domain?

Browser extension needs attention

If the extension credential expires or an administrator revokes this browser install, FlowMock immediately removes its generated redirect and session-header rules. Open Connect and choose Reconnect to FlowMock to authorize the browser again.

The extension works per site: each site you add is bound to its own environment, and a site that is not on the Connect page's Sites list is never touched. If nothing happens on a page, open DevTools → FlowMock on it: the bar at the top says whether FlowMock is on for the site, names the environment it matched, and turns it on in one click. Allow access means the browser still needs your permission for the site or its API. You can also check the Sites list for the exact origin (including the port for localhost). After turning a site on, reload the page so its requests go through FlowMock. If FlowMock itself is temporarily unavailable, use Try again or Open dashboard instead of changing switches whose result cannot be confirmed.

If the site's login breaks with the extension on, check Forward site cookies under the site's Advanced settings on the Connect page. It sends the cookies your browser already holds for the API; a login that sets new cookies through the proxy still needs you to sign in with FlowMock off for the site, or a custom domain.

See the Browser extension guide for the full walkthrough.

Sign out of this browser on the Connect page revokes the current install and clears its local credential, bind, discovery data, and generated rules. Uninstall revocation is best effort because browsers do not guarantee delivery of uninstall callbacks. To be certain, review and revoke the install under your account settings → Connected browser extensions.

CI-specific issues

401 from the Public API Check your API key - revoked, expired, or wrong prefix (fmk_…). Keys are in Settings → API keys.

403 plan_required Public API needs Team or Business plan.

Mocks work in dashboard but not CI Confirm CI sends the same x-flowmock-session value you configured via the API. Typos are undefeated.

See API authentication and Sessions API.

Still stuck?

Email support@flowmock.dev with:

Your proxy URL (redact if needed)
A session key you're testing with
A log entry id from the dashboard (if you have one)
What you expected vs what happened

We'll get you unstuck.