APIs are now the backbone of digital services, enabling everything from fintech integrations to customer data exchange. But as adoption skyrockets, so do risks. In 2025, failing to secure your APIs is not just a technical flaw—it’s a strategic liability.
This API Security Checklist will help you identify the blind spots, upgrade outdated practices, and align with financial-grade security standards. Based on insights from Raidiam and industry research, this guide is designed to move your organization from "Act Urgently" to "You’re Good."
Recent Raidiam research found that over 80% of enterprises had API defenses dangerously misaligned with the sensitivity of their data. Weak authentication, poor access control, and inadequate monitoring are the norm - especially outside regulated environments like Open Banking.
Even high-profile firms are not immune. The Dell customer data breach in 2023, where 49 million records were compromised via an unsecured partner API, proved just how devastating a single API flaw can be.
Use the checklist below to assess and harden your API security posture.
🔲 Eliminate API keys and shared secrets
🔲 Implement OAuth 2.0 with PKCE, Private Key JWT, or Mutual TLS (mTLS)
🔲 Use certificate-bound tokens to prevent token replay attacks
🔲 Rotate private keys regularly and store them securely (e.g., in HSMs or vaults)
Only one of 68 organizations in Raidiam’s survey used full mTLS and certificate-bound tokens—a setup mandated in Open Banking frameworks.
→ Download Now: API Security Report: Helping Enterprises Recognize and Address Critical Risks
🔲 Implement Attribute-Based Access Control (ABAC)
🔲 Use OAuth scopes to limit access based on the client and user context
🔲 Ensure APIs don’t expose more data than necessary (least privilege principle)
Over 70% of surveyed organizations lacked any form of contextual or fine-grained access control, making them highly vulnerable to excessive data exposure.
Related article: The API Security Gap: Why Most Enterprises Are Still Vulnerable
🔲 Treat every request as untrusted by default, regardless of network location
🔲 Authenticate and authorize per request using dynamic, context-aware controls
🔲 Leverage service mesh or API gateways with mTLS and identity validation
NIST’s Zero Trust model is fully compatible with mutual TLS, JWT, and runtime authorization strategies.
🔲 Ensure all API traffic runs over TLS 1.2+, preferably with mutual TLS
🔲 Use JWE/JWS for payload encryption and integrity
🔲 Validate request signatures for critical APIs (e.g., webhook verification)
Related read: Securing Data with JSON Web Encryption (JWE)
🔲 Perform API-specific penetration tests regularly
🔲 Deploy real-time monitoring and anomaly detection tools
🔲 Set up rate limiting, IP allow-lists, and logging for every endpoint
🔲 Audit usage patterns to catch abuse early (e.g., data scraping attempts)
One company in Raidiam’s study discovered that an attacker had been scraping their API for weeks before being detected - due to a lack of monitoring.
Related article: Why API Security Vulnerabilities Should Keep You Up at Night
🔲 Adopt the Financial-grade API (FAPI) security profile
🔲 Implement RFC 8705 (OAuth 2.0 Mutual TLS Client Authentication)
🔲 Use JARM/JAR for signed authorization requests and responses
🔲 Stay current with the OWASP API Security Top 10 threats
Related article: Securing Authorization Requests and Responses with JAR and JARM
🔲 Assign ownership of API security across product, engineering, and security teams
🔲 Train developers on OAuth, cryptography, and secure API coding practices
🔲 Conduct red/blue team exercises focused on APIs
🔲 Consider working with API security platforms or trust framework providers (e.g., Raidiam) to accelerate secure onboarding and implementation
If you find your organization checking more red boxes than green, you're not alone - but you must act now.
APIs are no longer just a technical domain - they’re a frontline for innovation and exploitation. Whether you’re in finance, health tech, retail, or SaaS, the message is clear: API security can no longer be an afterthought.
This API Security Checklist is your blueprint to modernize defenses, protect sensitive data, and stay ahead of regulators, attackers, and customer expectations.
Get your hands on Raidiam’s full API Security Report - a must-read guide that dives deep into today’s biggest API security risks, real-world breaches, and the best practices trusted by leaders in finance and tech.
Inside, you’ll find:
👉 Don’t wait for an incident to expose your vulnerabilities. Download the report now and start fortifying your APIs with proven, modern defenses.