Data Validation at Every Layer
Client, API, database — defense in depth for data integrity across your entire stack.
Every application has a front door (the UI), a hallway (the API), and a vault (the database). A good security system doesn't put a lock on just one of those — it secures all three. Data validation works the same way.
Defense in depth means validating data at every layer of your stack: the client, the API, and the database. Each layer catches different kinds of errors and serves a different purpose. Skip any layer and you've left a gap that bad data will find.
The most dangerous myth in software development is "we validate on the frontend, so we're fine." The frontend is the easiest layer to bypass. The database is the only layer that can't be bypassed.
Why Every Layer Matters
Each validation layer serves a distinct purpose:
Client-side validation provides instant feedback.
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