Structured Outputs in Production: Engineering Reliable JSON from LLMs
· 10 min read
LLMs are text generators. Your application needs data structures. The gap between those two facts is where production bugs live.
Every team building with LLMs hits this wall. The model works great in the playground — returns something that looks like JSON, mostly has the right fields, usually passes a JSON.parse. Then you ship it, and your parsing layer starts throwing exceptions at 2am. The response had a trailing comma. Or a markdown code fence. Or the model decided to add an explanatory paragraph before the JSON. Or it hallucinated a field name.
The industry has spent three years converging on solutions to this problem. This is what that convergence looks like, and what still trips teams up.
