Now in Public Beta

Fix LLM JSON
outputs

Make AI outputs deterministic, reliable, and production-ready.
Rule-based validation without LLM costs or hallucinations.

< 1ms Latency

Zero LLM Costs

100% Rule-Based

Try It Live

Experience Marshal's capabilities in real-time. No signup required.

Automatically repair malformed JSON with missing quotes, trailing commas, and other common syntax errors.

Validate JSON against OpenAPI specifications. Supports both JSON and YAML schema formats.

All processing happens server-side. Your data is never stored. No JavaScript required.

Deterministic reliability built for production-grade AI applications

Pure rule-based engine fixes LLM outputs without AI inference. Type coercion, default values, and schema healing—no hallucinations, no extra costs.

Proprietary TOON format strips JSON overhead. Same data, 50%+ fewer tokens. Cut your LLM API costs in half while improving readability.

Sub-millisecond validation on a high-concurrency Golang stack. Built for Super-App scale with performance that won't slow you down.

Upload your OpenAPI spec once. Every agent response is validated, type-safe, and production-ready. Automated QA for your AI outputs.

< 1ms

Validation Latency

Sub-millisecond processing

Additional LLM Calls

Zero extra token costs

100%

Schema Compliance

Guaranteed type safety