JSON mode explained: when schema enforcement beats prompting
JSON mode vs structured output: how constrained decoding works, when 3% failure rates become a real cost, and which enforcement approach your pipeline needs.
Tag · structured-output
JSON mode vs structured output: how constrained decoding works, when 3% failure rates become a real cost, and which enforcement approach your pipeline needs.
Which LLMs hit 99%+ JSON schema compliance natively in 2026, which need format enforcement middleware, and the real cost of retries at scale.
We benchmarked 4 LLMs on 6 real OCR tasks: receipts, invoices, prescriptions. GPT-5.5 wins 10/18 matchups; Haiku 4.5 crumbles on JSON formatting.