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Harry Smith is a passionate and versatile content writer with a knack for turning words into compelling stories. With a keen eye for detail and a deep love for the written word, Harry crafts content that not only informs but also engages and captivates readers.

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Harry

Harry

27-Jan-2026

API input validation means checking incoming data to make sure it’s correct, safe, and expected before processing it.

Common ways to validate API inputs:

  • Check required fields
    Ensure mandatory parameters are present.
    Example: email, password must not be empty.
  • Validate data types
    Confirm inputs match expected types (string, number, boolean, array).
  • Apply format rules
    Use patterns or rules:
    • Email format
    • Date format (ISO 8601)
    • Phone number pattern
  • Set length & range limits
    • String length (min/max)
    • Number range (e.g., age 1–120)
  • Whitelist allowed values
    Accept only known values (e.g., role = admin | user).
  • Sanitize inputs
    Remove or escape harmful characters to prevent SQL injection, XSS, etc.
  • Use validation libraries
    Examples:
    • Node.js: Joi, Yup, Zod
    • Java: Hibernate Validator
    • Python: Pydantic, Marshmallow
  • Return clear error responses
    Send meaningful messages with proper HTTP status codes (e.g., 400 Bad Request).

Best practice: Validate inputs at the API boundary before business logic runs.

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