Question 1

What is Helmet and which HTTP security headers should a Node.js API set?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js/Express security interviews. **Difficulty:** Easy > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The header diff below is **real, measured** output from two actually-running Express servers — genuine response headers, not a description of what Helmet's documentation says it does. ## 1. Why This Even Matters — A Story First A house with no lock on the door, no pee

Question 2

What are some common security best practices in Node.js applications?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js security-focused system-design interviews — assumes familiarity with the individual topics this answer cross-links to. **Difficulty:** Medium > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The `npm audit` and `helmet` results below came from **actually running both** against a real, deliberately-vulnerable setup on Node v24.19.0. ## 1. Why This Even Matters — A St

Question 3

How do you validate and sanitize request input (zod / joi)?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js API-security and input-validation interviews — assumes familiarity with the prototype-pollution question's real attack proof. **Difficulty:** Medium > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. Both the rejection and the field-stripping below were **actually run** with a real `zod` schema — genuine, specific validation issues, and a genuine, confirmed absence of

Question 4

How do you secure your Node.js API endpoints?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js API-security system-design interviews — assumes familiarity with the individual topics this answer cross-links to. **Difficulty:** Hard > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The `helmet()` header comparison below was **actually run** against two real Express servers on Node v24.19.0. ## 1. Why This Even Matters — A Story First A building's real security

NODE.JSDECODED.

Medium

What is Helmet and which HTTP security headers should a Node.js API set?

What are some common security best practices in Node.js applications?

How do you validate and sanitize request input (zod / joi)?

Hard

How do you secure your Node.js API endpoints?