data-validation

Validating and shaping data at every trust boundary in Node.js and NestJS services - HTTP input, env config, queue messages, upstream responses, and webhooks - with class-validator DTOs or Zod, whitelisting against mass assignment, coercion, query and pagination bounds, file upload validation, sanitisation versus validation, custom and cross-field validators, normalisation, response serialization, persisted JSON columns, unknown-field policy, and testing validators. Load when writing DTOs or schemas, validating input or config, handling uploads or webhooks, or shaping responses.