API Security Checklist for SaaS Developers

Use this API security checklist before shipping and operating a SaaS product that exposes HTTP APIs — whether you integrate third-party services like IdenticAPI or operate your own endpoints for customers. Copy sections into your release process, assign owners, and attach evidence (screenshots, CI job links, policy doc URLs) at sign-off.

Start with IdenticAPI-specific auth: Authentication documentation and API Keys documentation. Broader key hygiene: Protect API Keys in SaaS and API Key Rotation Best Practices.

1. Threat model and API surface inventory

• Document every API your SaaS exposes to customers (public REST, GraphQL, webhooks, MCP tools)
• Document every third-party API your backend calls (IdenticAPI, payment processors, RapidAPI validators)
• Classify data sensitivity per route (PII, payment metadata, secrets, public)
• Identify machine-to-machine vs user-delegated flows (OAuth vs API keys vs session cookies)
• Map trust boundaries: browser → your API → upstream providers
• Review Validation API vs In-House for externalized validation dependencies
• Named security owner for API surface reviews

2. Authentication

• All production routes require authentication unless explicitly public read-only
• No shared passwords embedded in mobile apps or SPAs
• IdenticAPI calls use Authorization: Bearer with idapi_live_ keys in production only — Authentication
• RapidAPI legacy calls (IBAN Validator, URL Inspector, etc.) use X-RapidAPI-Key — separate from IdenticAPI Bearer keys
• Failed auth returns generic errors — no user enumeration via distinct messages
• Constant-time comparison for API key validation on your customer-facing APIs
• Webhook endpoints verify sender signatures (HMAC, timestamp tolerance)
• Service accounts use distinct credentials per deployable — not one org-wide secret

3. Authorization and tenant isolation

• Every request resolves tenant/org context from authenticated session — not from client-supplied body fields alone
• Row-level isolation enforced in data layer (queries scoped by tenant_id)
• Admin endpoints require elevated role + optional MFA
• IDOR tests in CI — user A cannot fetch user B resources by ID guessing
• Agent and LLM tool calls inherit tenant scope from host auth — Agent Action Guard policies per tenant where applicable
• Cross-tenant cache keys namespaced
• Background jobs carry tenant context — no global queries without filter

4. API keys and secrets management

• Production secrets in secrets manager or encrypted env — never in git
• idapi_test_ keys only in dev/staging/CI; idapi_live_ only in production targets
• Keys shown once at creation — stored immediately — API Keys
• Dashboard key inventory: name, owner, services, last rotation date
• Rotation runbook tested in staging — Rotation best practices
• Revoked keys verified dead (401) in monitoring
• No NEXT_PUBLIC_, VITE_, or mobile bundle embedding of provider keys
• Secret scanning on repo (gitleaks, GitHub secret scanning)
• LLM paths scan for pasted keys — Prevent API Key Leak in AI Prompts

5. Input validation and output encoding

• Schema validation on all JSON bodies (Zod, JSON Schema, pydantic)
• Reject unknown fields where strict contracts required
• Max payload sizes enforced (body parser limits, reverse proxy)
• File upload type, size, and virus scan policy defined
• IBAN fields validated server-side via IBAN Validator or equivalent — Validate IBAN programmatically
• Card numbers validated before tokenization — Credit Card Validator; never log full PAN
• URLs inspected before server-side fetch — URL Inspector; use final_url after redirects
• HTML/JSON responses encoded appropriately — no reflected XSS in error messages
• LLM-generated content treated as untrusted before render — LLM output as untrusted input

6. Rate limiting and abuse prevention

• Per-IP and per-API-key rate limits on public endpoints
• Stricter limits on auth, password reset, and token issuance routes
• Burst + sustained limit configuration documented
• 429 responses include Retry-After where applicable
• Upstream provider rate limits understood (IdenticAPI usage docs, RapidAPI quotas)
• Cost anomaly alerts on third-party API spend
• Bot/scrape detection on high-value read endpoints

7. Transport and network security

• TLS 1.2+ everywhere — HSTS on customer-facing domains
• Internal service mesh or mTLS where policy requires
• Certificate renewal automated (Let's Encrypt, ACM)
• No sensitive data in URL query strings (keys, tokens, PAN)
• CORS allowlist explicit — no * with credentials
• Security headers: X-Content-Type-Options, Referrer-Policy, CSP on web apps

8. Logging, monitoring, and privacy

• Structured logs with correlation IDs across services
• Authorization headers and API keys redacted in logs
• PII minimization — log IDs not full email/card/IBAN where possible
• IdenticAPI request_id stored for support correlation
• Alert on auth error spikes, 5xx rates, latency SLO breaches
• Audit log for admin actions (key creation, role changes, data export)
• Log retention aligned with privacy policy
• Third-party log pipelines reviewed for data residency

9. Error handling and information disclosure

• Production errors return safe messages — stack traces server-side only
• Consistent error schema { error, code, request_id }
• 404 vs 403 policy documented (hide existence vs explicit forbidden)
• Debug endpoints disabled in production
• Health checks expose minimal info publicly

10. Webhooks and async integrations

• Webhook secrets rotated on compromise playbook
• Idempotency keys for payment and provisioning webhooks
• Replay protection (timestamp + signature window)
• Outbound webhook delivery retries with exponential backoff
• Dead letter queue for failed webhook processing

11. Dependency and third-party API security

• Inventory of all external HTTP dependencies with owner
• Pin SDK versions; dependabot or equivalent enabled
• Timeout and circuit breaker on outbound calls
• Fail-closed vs fail-open documented per dependency (payments vs optional enrichment)
• DPA/subprocessor list includes IdenticAPI and RapidAPI where applicable
• No calling user-supplied URLs without URL inspection and allowlist — Validate URLs for AI agents
• AI Security integrations server-side — AI Security product hub

12. AI-specific API security (if applicable)

• Prompt injection screening on untrusted input — Prompt Injection Shield
• PII/secrets scan before LLM provider calls — PII & Secrets Detection
• Output moderation before user display — AI Output Safety
• Unified orchestration evaluated — Unified Guard
• Agent tool calls gated — Agent Action Guard
• No production IdenticAPI keys in browser — Protect API keys
• Scam/phishing UX does not overclaim automated detection — Scam detection guide

13. CI/CD and deployment

• Separate staging/production secrets and keys
• Production deploy requires review or automated policy checks
• IaC secrets reference ARNs — not literals in Terraform state committed publicly
• Container images scanned for vulnerabilities
• Rollback procedure tested
• Post-deploy smoke tests hit authenticated API paths

14. Incident response

• Runbook: compromised customer API key (revoke, notify, audit access logs)
• Runbook: compromised IdenticAPI or RapidAPI key (rotate, review usage) — Rotation guide
• Runbook: upstream provider outage (degraded mode documented)
• Security contact published for researchers
• Post-incident review template updates this checklist

15. Compliance and customer commitments

• Privacy policy matches actual API data flows
• Customer DPA available if processing EU personal data
• Data export/delete APIs documented and tested
• PCI scope documented if touching card data — validation API ≠ PCI compliance alone
• No marketing claims of "unhackable" or "guaranteed secure APIs"

16. Testing and security verification

• Automated authz tests in CI (tenant isolation)
• OWASP API Security Top 10 review annually
• Periodic penetration test or bug bounty for public API
• Fuzz testing on critical parsers
• Synthetic tests: invalid tokens, expired keys, malformed JSON
• Load test validates rate limit behavior

17. Documentation and developer experience

• Public API docs describe auth, errors, rate limits
• Internal runbooks linked from on-call wiki
• IdenticAPI integration docs pinned: /docs/authentication, /docs/api-keys
• Customer-facing SDKs do not embed your upstream provider keys
• Changelog communicates breaking auth changes

18. Pre-launch sign-off

• Security reviewer signed checklist with date
• All [ ] items above either completed or accepted risk documented
• Engineering manager acknowledges known limitations
• On-call has access to key rotation and revoke procedures
• No placeholder TODO secrets in production config

Quick reference links

Architecture diagram (reference)

                    ┌─────────────────┐
                    │  Browser / App  │
                    └────────┬────────┘
                             │ session / customer API key
                             ▼
                    ┌─────────────────┐
                    │   Your SaaS API  │
                    │  authz + validate│
                    │  rate limit      │
                    └────────┬────────┘
           ┌─────────────────┼─────────────────┐
           ▼                 ▼                 ▼
   ┌──────────────┐  ┌──────────────┐  ┌──────────────┐
   │ IdenticAPI   │  │ RapidAPI     │  │ Your DB      │
   │ Bearer keys  │  │ validators   │  │ tenant scope │
   │ (AI Security)│  │ (IBAN/URL)   │  │              │
   └──────────────┘  └──────────────┘  └──────────────┘

Keys never flow from IdenticAPI upstream back to the browser. Customer API keys are distinct from your provider keys.

Limitations (read before sign-off)

Completing this checklist reduces common SaaS API failures but does not guarantee zero incidents:

• Checklists drift — re-run after major feature launches (AI agents, new payment flows, multi-region)
• Third-party providers introduce shared fate risk — monitor their status and error budgets
• Automated validation (IBAN, Luhn, URL metadata) does not replace business authorization
• AI guardrails are probabilistic — maintain human review for high-trust workflows

Treat this document as a living checklist. Update when you add MCP servers, public webhooks, new IdenticAPI products, or customer-facing API versions. Pair API hygiene with organization-wide security practices — this list focuses on what SaaS engineering teams control directly.

When every section has an owner, evidence, and a review date, you are in a stronger position to ship APIs that fail closed on auth errors, protect provider keys, and isolate tenant data — the baseline users and auditors expect from production SaaS.