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Stream Schema

NPM Package

Streaming JSON parser with incremental schema validation. Parse LLM outputs token by token. Real-time partial results with type safety as data arrives.

TypeScript
NPM
JSON Schema
LLM

Key Features

  • Incremental JSON parsing with partial value handling
  • JSON Schema draft-07 validation as data arrives
  • Full TypeScript type inference from schema
  • LLM error recovery (trailing commas, unquoted keys, single quotes)
  • Event callbacks for real-time UI updates
  • Memory-efficient streaming for large JSON files

Stream Schema is a streaming JSON parser with incremental schema validation. LLM outputs often arrive as JSON, token by token. Current solutions wait for the complete JSON before they parse it. This wait gives a bad user experience. Other solutions use fragile regex hacks.

The Solution

stream-schema parses JSON incrementally as the data streams. It validates the data against a JSON Schema. It emits partial results that you can use to update your UI in real time.

Key Features

  • Incremental Parsing: Parses JSON as it streams, with no wait for completion
  • Schema Validation: Validates against JSON Schema draft-07 incrementally
  • TypeScript Support: Full type inference from your schema
  • LLM Error Recovery: Recovers from common LLM mistakes (trailing commas, unquoted keys)
  • Event Callbacks: Real-time callbacks for field completions and validation errors

Tech Stack

  • Language: TypeScript
  • Build: tsup (ESM + CJS)
  • Testing: Vitest (102 tests)
  • Package: Published on NPM as stream-schema

Live Demo

Open the live demo at v0-llm-output-parser.vercel.app