SchemaFirst

SchemaFirst — CSV → JSON You Can Actually Ship

Most CSV → JSON converters stop at “valid.”

SchemaFirst goes further and tells you whether your data is actually safe to use.

SchemaFirst is a browser-only, schema-aware CSV → JSON tool that infers types, detects anomalies, and makes every assumption visible — before your data hits production.

No uploads. No servers. No guessing.

What You Get

• Typed JSON output
• Numbers, booleans, dates, and strings inferred automatically.
• Inferred schema with confidence scores
• See exactly how sure the tool is about each column.
• Clear warnings, not silent failures
• Mixed types, empty-heavy columns, invalid values — all surfaced.
• Clean vs Strict outputs
• Clean: keep all rows, coerce invalid values to null
• Strict: drop rows that violate the schema
• One-click exports
• Export Clean JSON, Strict JSON, or the inferred schema.

Why SchemaFirst Exists

Real-world CSVs are messy.

Valid JSON doesn’t mean good JSON.

SchemaFirst is designed for developers who want:

• predictable data
• auditability
• confidence before shipping

It tells you what it changed, what it dropped, and why.

How It Works

1. Paste your CSV
2. Review the inferred schema and warnings
3. Export JSON you can trust

Everything runs entirely in your browser.

What It’s Not

• Not Excel
• Not a data visualization tool
• Not a “handle every edge case ever” parser

SchemaFirst is opinionated by design — predictable over clever.

SchemaFirst

Good JSON starts with a good schema.