AI tool comparison
Structured Output Benchmark vs SmolDocling
Which one should you ship with? Here is the side-by-side panel verdict, pricing read, reviewer split, and community vote comparison.
Developer Tools
Structured Output Benchmark
The benchmark that tests whether LLMs get JSON values right, not just syntax
75%
Panel ship
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Community
Free
Entry
Interfaze's Structured Output Benchmark (SOB) exposes a gap that has been quietly breaking production AI pipelines: models can produce syntactically valid JSON while getting the actual values wrong. SOB measures value accuracy across 21 models using 5,000 text passages, 209 OCR documents, and 115 meeting transcripts — scoring each on seven metrics including value accuracy, faithfulness (grounding vs. hallucination), type safety, and perfect-response rate. The benchmark reveals some sobering findings. Even top models like GPT-5.4 and Claude Sonnet 4.6 achieve ~83% on text but drop to 67% on images and only 23.7% on audio. No single model dominates all modalities — GPT-5.4, GLM-4.7, Qwen3.5-35B, and Gemini 2.5 Flash cluster within one point of each other on text. Perfect response rates (all seven metrics correct) rarely exceed 50% for even the best performers. For developers building data extraction pipelines, agents that read invoices, or any system where "correct JSON" means more than syntactically valid JSON, this is required reading. The dataset is on Hugging Face, the paper is on arXiv, and the playground lets you test your own model's structured output capability directly.
Developer Tools
SmolDocling
256M-param VLM that converts any document to structured text
75%
Panel ship
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Community
Free
Entry
SmolDocling is a 256-million-parameter vision-language model from IBM Granite that converts documents — PDFs, scanned papers, tables, charts, forms — into clean, structured text with remarkable accuracy for its size. It introduces a new markup format called DocTags that captures not just text but document structure, reading order, and element types (headings, captions, tables, code blocks) in a way that downstream models and parsers can reliably consume. The "smol" in the name is intentional: at 256M parameters, SmolDocling runs fast enough to be deployed in production pipelines where larger VLMs would be prohibitively slow or expensive. Despite its compact size, IBM reports it achieves state-of-the-art performance across multiple document type benchmarks — outperforming much larger models on structured document parsing tasks. The key innovation is the DocTags format, which gives the model a precise vocabulary for describing document elements rather than trying to reconstruct structure from freeform text output. Built on top of the docling project (58.7k GitHub stars), SmolDocling is open source under Apache 2.0 and available on HuggingFace. The technical report is on arXiv (2503.11576). For teams building RAG pipelines, document intelligence tools, or any system that needs to ingest unstructured documents at scale, this is a practical, deployable solution.
Reviewer scorecard
“This is the benchmark I've been waiting for. 'Valid JSON' is table stakes — the real question is whether field values are correct. This plugs a genuine gap in how we evaluate extraction pipelines.”
“256M params that actually handle real-world PDFs including tables, charts, and mixed layouts — this goes straight into my RAG preprocessing pipeline. The DocTags format is smart: giving the model a precise document vocabulary instead of asking it to improvise structure from scratch.”
“The 23.7% audio accuracy stat sounds alarming but the test data is text-normalized before scoring, meaning ASR errors are excluded. It's a better benchmark than most but the methodology choices deserve more scrutiny before you rely on it for vendor selection.”
“IBM's benchmark numbers for SmolDocling were measured on datasets curated by the same team. Real-world document parsing — especially for scanned documents with skew, noise, or unusual layouts — is where small VLMs consistently fall apart. Test it on your actual documents before committing it to production.”
“No universal winner across modalities is the real story here. As agentic systems increasingly handle mixed-media inputs, this exposes that model selection needs to be task-specific. Benchmarks like SOB are how the industry gets smarter about that.”
“Efficient document parsing is critical infrastructure for the AI economy — most enterprise knowledge lives in PDFs and Word docs, not clean databases. A 256M model that can do this well enough to be deployed in high-throughput pipelines removes a major bottleneck from enterprise AI adoption.”
“For anyone automating content workflows that extract structured data from documents, briefs, or meeting recordings, this tells you which model to actually trust for each media type. Genuinely useful before you commit to an architecture.”
“Finally being able to reliably extract content from design-heavy PDFs — charts, callouts, multi-column layouts — without everything turning into garbage text is genuinely useful for content repurposing workflows. DocTags also makes it easier to preserve the editorial structure of source documents.”
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