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Mridu Dixit
Mridu Dixit

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Top 10 API Call Security Mistakes Developers Still Make in 2025

#webdev #programming #javascript #productivity

Introduction

Even in 2025, API call security remains one of the biggest weaknesses in modern applications. With more frontend-heavy apps, more third-party integrations, and more public APIs, developers are still repeating the same mistakes—leading to data leaks, token theft, and full application compromise.

Here are the top 10 API call security mistakes developers still make in 2025, and how to fix them.

1. Exposing API Keys in Frontend Code

Yes, it still happens.

  • Publishing API keys inside:
  • Angular/React source code
  • environment.ts files
  • mobile builds (APK/IPA)

…makes them accessible to anyone.

✅ Fix:

  • Never trust frontend to hide secrets
  • Move sensitive calls to a backend or Cloud Function proxy
  • Use restricted API keys with domain-level rules

2. Using Only Client-Side Validation

Client-side validation is easily bypassed with:

  • Postman
  • cURL
  • Browser network tab edits Relying on frontend checks leaves the backend wide open.

✅ Fix:

Perform all critical validation on the server (auth, role checks, payload checks).

3. Missing Proper Authentication (Tokenless API Calls)

Some developers still allow API endpoints to be accessed without:

  • JWT
  • OAuth2 token
  • API key
  • Session cookie

This leads to data leaking in minutes.

✅ Fix:

  • Enforce auth on every request.
  • No public endpoints unless explicitly intended.

4. Storing JWT Access Tokens in LocalStorage

Storing tokens in localStorage is still a major attack vector.

Reason:
If the site gets an XSS, attackers steal the token instantly.

✅ Fix:

Use:

  • HttpOnly cookies for access/refresh tokens
  • Short-lived tokens
  • Token rotation

5. Not Implementing Rate Limiting

Hackers abuse APIs by:

  • Brute forcing logins
  • Sending 10k requests per second
  • Enumerating users
  • Without rate limits, your APIs burn quickly.

✅ Fix:

Enable rate limiting at:

  • API Gateway
  • Cloudflare/WAF
  • Backend server

6. No Authorization Checks (Role / Permission Validation)

Many APIs authenticate users but never check permissions.

Examples:

  • User A can access User B’s data
  • Non-admins calling admin APIs
  • Direct object reference (IDOR) attacks

✅ Fix:

Always validate:

  • Role
  • Permissions

  • Resource ownership

    1. Passing Sensitive Data Without Encryption Sending passwords, tokens, or personal data over non-HTTPS is a disaster.

Yes—developers still do it in dev/staging.

✅ Fix:

E

  • nforce HTTPS
  • Use HSTS
  • Reject mixed content

8. Not Validating Request Payloads

Hackers send:

  • Extra fields
  • Missing fields
  • Malicious JSON
  • Overly large payloads

Without schema validation, your API breaks or leaks data.

✅ Fix:

Use:

  • Zod / Yup
  • Joi
  • JSON schema

  • Validation pipes (NestJS)

    1. Overly Verbose Error Messages Returning errors like: 
User not found in DB table users_master
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or

JWT expired at 2025-01-20T10:32:18Z
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leaks internal logic to attackers.

✅ Fix:

Send generic safe responses:

Invalid credentials.
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Log detailed errors on backend only.

10. No Logging & Monitoring

Developers often don’t track:

  • Failed requests
  • Suspicious API activity
  • Repeated auth failures
  • Sudden traffic spikes
  • This lets attackers run unchecked.

✅ Fix:

Use:

  • Firebase Monitoring
  • Cloud Logging
  • ELK / Datadog
  • Alerts for unusual API patterns

Conclusion

API security is no longer optional—it's a survival requirement in 2025.
Avoiding these 10 mistakes will make your applications safer, harder to attack, and more reliable.

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