How I Would Fix exposed API keys and missing auth in a Circle and ConvertKit AI-built SaaS app Using Launch Ready.

Opening

If I see exposed API keys and missing auth in a Circle and ConvertKit AI-built SaaS app, I assume two things immediately: someone moved fast without a security boundary, and the product is already one mistake away from data exposure or billing abuse.

The most likely root cause is that the app was shipped with secrets in the frontend, in a public repo, or in build-time variables that got bundled into client code. The first thing I would inspect is the deployment surface: the live site source, environment variables in the host, and any Circle or ConvertKit calls happening from the browser instead of a server route.

If auth is missing, I also assume the product has no real trust model yet. That means anyone who finds a URL can probably access customer data, trigger automations, or create records without proving who they are.

Triage in the First Hour

1. Check the live app in an incognito browser.

• Try every key flow without logging in.
• Confirm whether private pages, API routes, and admin screens are accessible.

2. Open browser dev tools and inspect network calls.

• Look for Circle or ConvertKit requests made directly from the client.
• Check whether any secret-looking token appears in request headers, query strings, or bundled JS.

3. Review the frontend bundle source.

• Search for `circle`, `convertkit`, `api_key`, `secret`, `token`, `webhook`, and `Bearer`.
• Confirm whether sensitive values are embedded in shipped code.

4. Inspect hosting environment variables.

• Check Vercel, Netlify, Cloudflare Pages, Render, Railway, or similar.
• Verify which variables are public versus server-only.

5. Audit Circle and ConvertKit dashboards.

• Review API key scopes, last used time, webhook settings, and connected apps.
• Rotate anything that may have been exposed.

6. Check logs and analytics.

• Look for unusual spikes in requests, signups, email sends, failed auth attempts, or webhook calls.
• Compare against normal traffic from the last 24 to 72 hours.

7. Inspect deployment history.

• Find when secrets were introduced into code or when auth was removed.
• Identify the exact release that caused the breakage.

8. Review routes and middleware.

• Confirm there is real server-side protection on protected pages and APIs.
• Make sure client-side hiding is not being mistaken for authentication.

9. Check email automation triggers.

• Verify whether ConvertKit sequences can be triggered without authorization.
• Look for forms or endpoints that accept arbitrary submissions.

10. Freeze risky changes until containment is done.

• Stop new deploys if needed.
• Rotate secrets before making code changes if exposure is confirmed.

A quick diagnostic command I would run locally:

grep -RInE "circle|convertkit|api[_-]?key|secret|token|bearer" .

That will not solve anything by itself, but it quickly tells me where the danger lives.

Root Causes

| Likely cause | What it looks like | How I confirm it | |---|---|---| | Secrets hardcoded in frontend code | Tokens visible in JS bundle or repo | Search source and built assets; inspect network requests | | Public env vars used for private keys | `NEXT_PUBLIC_` or equivalent prefix on sensitive values | Review host env names and build config | | No server-side auth guard | Protected pages load for anonymous users | Hit routes directly in incognito and via curl | | Client talks to Circle or ConvertKit directly | Browser makes privileged API calls | Inspect network tab and app code paths | | Weak webhook protection | Webhooks accept unauthenticated requests | Review endpoint checks, signatures, and replay protection | | Stale test keys promoted to prod | Sandbox credentials still active in production | Compare dashboard keys against deployed env values |

The most common pattern I see with AI-built SaaS apps is this: the builder used whatever was easiest to get working first. That often means calling third-party APIs from React components because it feels fast during prototyping. It works until a user opens dev tools and sees everything they should not see.

Another common issue is "auth by UI". The app hides buttons if you are not logged in, but the backend never checks identity. That is not security. That is decoration.

The Fix Plan

First, I would contain exposure before touching features.

• Rotate all exposed Circle and ConvertKit API keys immediately.
• Revoke any unused tokens and remove old webhooks tied to those credentials.
• Assume anything already shipped to browsers or logs is compromised.

Next, I would move all privileged third-party calls behind server-side endpoints.

• Create backend routes for Circle membership actions and ConvertKit subscriber actions.
• Keep secret keys only on the server.
• Return only sanitized responses to the frontend.

Then I would add real authentication at the application boundary.

• Protect every private page with session-based auth or signed JWT verification on the server.
• Enforce authorization per resource, not just per route.
• Block direct access to user records unless ownership is verified on every request.

For example:

// Pseudocode only
if (!session?.userId) return new Response("Unauthorized", { status: 401 });

const record = await db.records.findFirst({
  where: { id: params.id, userId: session.userId },
});

if (!record) return new Response("Forbidden", { status: 403 });

Then I would fix how secrets are stored and deployed.

• Move production secrets into host environment variables only.
• Remove any secret from git history if it was committed publicly.
• Use separate keys for dev, staging, and production so one leak does not take down everything at once.

After that I would harden webhook handling.

• Verify signatures where supported by Circle or ConvertKit.
• Reject unsigned requests.
• Add idempotency so duplicate events do not create duplicate users or emails.

Then I would clean up access patterns around email automation.

• Only allow authenticated users to trigger subscriber changes tied to their own account.
• Add rate limits on forms and mutation endpoints.
• Log every privileged action with user ID, timestamp, IP hash, and request ID.

Finally, I would deploy safely.

• Ship behind a feature flag if auth changes affect onboarding flows.
• Test on staging with production-like secrets removed.
• Roll out first to internal users before full release if possible.

The business goal here is simple: stop unauthorized access without breaking signups or email delivery. If you rush this fix badly, you can trade one incident for another by blocking legitimate users from onboarding or breaking your ConvertKit automations entirely.

Regression Tests Before Redeploy

I would not redeploy until these checks pass:

1. Anonymous access test

• Open private routes in incognito.
• Expected result: redirect to login or 401/403 response.

2. Secret leakage test

• View page source and built JS bundles.
• Expected result: no API keys, tokens, webhook secrets, or private URLs appear client-side.

3. Third-party call test

• Trigger Circle and ConvertKit actions from a normal user session.
• Expected result: browser never talks directly to privileged endpoints; server handles them instead.

4. Authorization test

• Try accessing another user's record by changing IDs in URLs or requests.
• Expected result: denied every time unless ownership matches.

5. Webhook validation test

• Send malformed or unsigned webhook payloads to staging only.
• Expected result: rejected with clear logs; no side effects created.

6. Rate limit test

• Repeat signup or form submission rapidly from one IP/session.
• Expected result: throttling kicks in before abuse becomes expensive.

7. Email flow test

• Complete onboarding end-to-end with a real test inbox on staging.
• Expected result: correct subscriber added once; correct sequence triggered once; no duplicates.

8. Log review test

• Confirm sensitive values are redacted from application logs.
• Expected result: no full tokens or personal data dumped into error output.

Acceptance criteria I would use:

• 100 percent of private routes require auth on the server side.
• Zero secrets appear in shipped frontend bundles.
• All privileged actions are logged with traceable user context.
• No unauthorized request can read or mutate another user's data.
• Staging smoke tests pass twice before production deploys go out.

Prevention

I would put four guardrails around this class of failure so it does not come back next week when someone ships another AI-generated change set at speed.

Security guardrails

• Add pre-deploy secret scanning with tools like GitHub secret scanning or Gitleaks.
• Require least privilege for all Circle and ConvertKit tokens.
• Rotate production credentials on a schedule every 60 to 90 days if feasible.

Code review guardrails

• Never approve client-side API calls that use private credentials unless there is a very explicit reason documented in review comments.
• Require an auth check checklist on every PR touching routes, webhooks, billing logic, email flows, or admin screens.
• Review behavior first: who can do what, what data moves where, what breaks if this fails?

UX guardrails

• Make login state obvious to users so they know when they are protected versus guest mode.
• Show clear permission errors instead of silent failures that confuse support teams later on.
• Keep onboarding simple but never let simplicity erase identity checks on sensitive actions.

Monitoring guardrails

• Alert on unusual spikes in API usage from Circle or ConvertKit integrations within 5 minutes of detection window breach thresholds you define internally as suspicious behavior starts above baseline by 3x to 5x traffic rate).
• Track failed auth attempts separately from normal errors so you can spot probing early.
• Watch p95 latency on protected endpoints; if it jumps above 500 ms after adding auth middleware,

profile it before it becomes a conversion problem at signup time).

Performance guardrails

• Cache safe read-only responses where possible after authorization checks succeed

so security does not turn into slow pages).

• Keep third-party scripts out of critical rendering paths where they hurt LCP and INP).

When to Use Launch Ready

Use Launch Ready when you need me to turn this from a risky prototype into something you can actually put in front of customers without crossing your fingers every time someone signs up).

( Domain setup, ( email setup, ( Cloudflare, ( SSL, ( redirects, ( subdomains, ( caching, ( DDoS protection, ( SPF/DKIM/DMARC, ( production deployment, ( environment variables, ( secrets, ( uptime monitoring, and handover docs).

This sprint fits best when you already have a working AI-built SaaS app but cannot trust its launch setup yet). If your product uses Circle for community access) or ConvertKit for onboarding emails), I will make sure those integrations sit behind proper server-side controls instead of leaking through the browser).

What you should prepare before booking: 1. Access to your domain registrar) 2. Access to hosting/deployment platform) 3. Admin access to Cloudflare) 4. Circle admin access) 5. ConvertKit admin access) 6. A list of current environments) 7. Any existing repo links) 8. A short note on what should be public versus private)

If your issue includes exposed secrets plus missing auth), Launch Ready gives me enough runway to secure the launch path fast without dragging you into a long rebuild). If you also need deeper app refactoring), I will tell you plainly whether this should stay a sprint or become a larger rescue engagement).

Delivery Map

References

1. https://roadmap.sh/cyber-security 2. https://roadmap.sh/api-security-best-practices 3. https://roadmap.sh/code-review-best-practices 4. https://docs.circle.so/ 5. https://developers.convertkit.com/

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Take the next step

If this is a problem in your product right now, here is what to do next:

• [Use the free Cyprian tools](/tools) - estimate cost, score app risk, check launch readiness, or pick the right service sprint.

• [Book a discovery call](/contact) - I will tell you honestly whether you need a sprint or if you can DIY the next step.

*Written by Cyprian Tinashe Aarons - senior full-stack and AI engineer helping founders rescue, launch, automate, and scale AI-built products.*