API Scan Guide: How to Detect High-Severity Flaws in AI-Built Apps

Quick answer: An API scan sends requests to programmatic interfaces and reports the issues its checks support. Review its endpoint, authentication, and payload coverage. Combine the results with code review and application-specific authorization tests before release.

By Daniel A · Kraftwire Software

Why Is an API Scan Critical for AI-Built Applications?

An API scan sends requests to programmatic interfaces. It can help identify supported problems, but does not verify every data boundary. Combine scanning with code review and authenticated tests against the application’s intended access policy.

These live figures describe all scanned sites. They do not establish prevalence for an AI-built subgroup, compare development methods, or attribute findings to AI generation.

13% of the 119 live sites SimplyScan has scanned (15 sites) have at least one high-severity web-security issue, such as a missing Content-Security-Policy or HSTS header.

Web-security findings can include missing security headers or transport-layer flaws. Review generated code and deployment configuration independently of whether the visible features work.

How Does Automated API Scanning Work for Developers?

API scanners differ in discovery, payloads, credentials, and assertions. Some use an API description to compare responses with documented behavior; others probe selected endpoints for known issue patterns. Check the actual configuration and coverage.

A scanner that supports command-line or API execution can be integrated into a deployment workflow. Configure the target environment, permitted tests, and how findings are reviewed. A repeat scan detects only changes within its coverage.

Coverage to Inspect

• Endpoint Discovery: Which routes were supplied or discovered, and which were missed?
• Payloads: Does the tool send malformed input, or only make passive observations?
• Authorization: Which users, roles, and tokens were tested? An anonymous response check is not authenticated cross-user testing.

Which API Flaws in Vibe-Coded Apps Should You Check?

Review generated code and deployment configuration independently of whether the visible features work.

11% of the 119 live sites SimplyScan has scanned (13 sites) have at least one medium-severity architecture issue, such as a library with a known vulnerability or no rate limiting.

Investigate individual findings and their check definitions before attributing a cause or interpreting the aggregate category.

Broken Object-Level Authorization (BOLA)

For an endpoint such as /api/user/123, check whether the caller may access the requested record. The following SQL query does not by itself establish that permission, although other controls such as RLS may enforce it:

Review the query together with its server-side authorization. The illustrative fragment AND owner_id = $current_user expresses an ownership check; it is not valid PostgreSQL parameter syntax to paste unchanged. Bind a server-verified identity using the driver’s parameter syntax and match the application’s sharing model.

Exposed Secrets and Keys

Inspect accessible bundles and repositories for credential patterns with the secret scanner. Investigate each match and revoke leaked secrets. A credential’s permissions and usability determine its impact.

30% of the 119 live sites SimplyScan has scanned (36 sites) have at least one high or critical security issue.

How to Scan an API for Vulnerabilities Manually?

Manual testing can examine application-specific behavior outside scan coverage. The JWT debugger decodes token structure and supports limited signature checks; it does not verify the application’s validation logic. Do not place secrets in an ordinary signed JWT payload, which is readable.

Map your endpoints

List every URL your frontend calls.

Test for IDOR

With test accounts and records you control, change a resource ID and compare the response with the intended access policy.

Check CORS settings

Inspect Access-Control-Allow-Origin: * in context. It permits non-credentialed cross-origin response sharing, which may be intentional for public data; it is not itself proof of CSRF. Review authentication, authorization, and CSRF defenses separately.

Validate Input

In an isolated test environment, send values that violate the endpoint’s schema and inspect validation and error handling. Public errors should not disclose private data or internal diagnostics.

Can You Automate API Scanning in Cursor or Windsurf?

An MCP server can expose tools for an editor agent to invoke. SimplyScan’s MCP integration can scan a deployed URL and return findings. Review proposed code changes and re-test them; a scan-to-fix workflow does not guarantee that the agent repairs the issue.

For Windsurf or Cursor, decide which checks run on local code and which need a deployed test URL. A URL scan cannot inspect an uncommitted change that has not been deployed.

29% of the 119 live sites SimplyScan has scanned (35 sites) have at least one medium-severity web-security issue, such as a missing Content-Security-Policy or HSTS header.

What Is the Difference Between DAST and API Scanning?

DAST tests a running application through its exposed interfaces. Dynamic API testing is one form of DAST; some tools also interact with rendered browser pages. Coverage depends on the tool and configuration.

Browser-Oriented Checks

A tool may exercise forms and navigation or inspect response headers. Verify which browser behavior it actually tests.

API-Oriented Checks

A tool may test input handling, selected authorization cases, or rate controls. Supabase RLS and Firebase rules need tests matched to their own access models; a generic scan does not verify all policies.

How Do You Fix High-Severity API Flaws?

Prioritize confirmed findings by impact, exposure, and the affected operation. The repair may be a code, configuration, or design change. Examples to investigate include:

• Access Controls: Review database grants and applicable row policies, then test allowed and denied access.
• Exposed Secrets: Revoke leaked credentials, update legitimate uses, and investigate exposure. The exposed files tool performs bounded public-path probes; it cannot find every copy.
• Gateway Controls: A gateway can centralize some checks, but application-specific authorization remains necessary.

Why Does SimplyScan Focus on AI-Built Apps?

SimplyScan provides bounded public URL checks for applications built with Lovable, Bolt, v0, or other tools. Review recognizable exposed secret patterns, security headers, and supported anonymous backend observations alongside manual security testing.

The average security score across the 119 live sites SimplyScan has scanned is 86 out of 100.

A free scan on SimplyScan grades 8 dimensions in one pass · security, speed, SEO, AI visibility (AEO), accessibility (WCAG), GDPR/compliance signals, domain health and email security (SPF/DKIM/DMARC) · in ~30 seconds, no signup. Use an api scan to identify detectable risks as part of a broader release review.

How to Maintain API Security Over Time?

Changes can alter API exposure and authorization. Repeat relevant tests after deployment and monitor supported signals. Neither monitoring nor a previous clean scan establishes that no critical regression exists.

Pro Monitoring includes Pro scan credits for full reports. See pricing for the allowance associated with your chosen option.

• Rescans: Pro Monitoring includes scheduled rescans with change alerts; use them to investigate detectable changes.
• Uptime: Uptime monitoring reports availability observations for configured URLs.
• Badge: A verified badge links to a dated scan’s score and eligibility state under the badge criteria. It does not prove the absence of vulnerabilities.

Use API scan findings to guide investigation, then verify repairs with tests covering the affected operation.