Validating JSON Payloads Against a Schema Before They Hit Your Service

<p>A few years ago, I shipped what looked like a textbook, harmless API update.</p> <p>The endpoint returned valid JSON. Every single local test passed with flying colors. We hit

<h1> I Built a Browser-Only JSON Schema Validator — Draft-07, $ref, allOf/anyOf/oneOf, if/then/else, 173 Tests </h1> <p>JSON Schema validation usually means pulling in

<p>For a long time the trick to force a model into JSON was to prefill the assistant turn with an opening brace. That trick is dead on the current Claude models. It returns a 400.

<p>In web development, there is one golden rule: <strong>Never trust user input.</strong> Whether it is a login form, a search bar, or an environment variable, unvalidated data is