JSON to BigQuery Schema

Stop typing column definitions. Paste JSON, get your table schema. Works with nested data and arrays.

JSON Input

BigQuery Schema (JSON)

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Why I Built This

Because manual DDL writing was killing my productivity

I got tired of writing BigQuery schemas by hand.

The Annoying Reality

Every time I had a new data source, I had to manually figure out column types, handle nested JSON, and write the schema JSON or DDL. One wrong type and my pipeline would fail.

The Simple Fix

I built this to automate the boring part. Now I paste JSON, get the schema, and move on with building actual data pipelines.

What I Focused On

  • Runs locally - your data never leaves your browser
  • Handles real-world JSON - nested objects, arrays, messy data
  • No bloat - just the schema you need, nothing extra

How It Works

Nothing fancy. Just a JSON parser that maps types to BigQuery equivalents. No AI, no servers, no complexity.

The editor is CodeMirror - lightweight and fast. All processing happens in your browser.

Who This Is For

Data engineers, analytics engineers, and anyone who uses BigQuery.

No tracking, no data collection, no BS.

— A data engineer who got tired of manual schemas

How It Works

Three steps to a production-ready schema

Paste Your JSON Copy your JSON data into the editor. Sample data works best.

Pick Output Format Choose JSON schema for the BigQuery API or DDL for CREATE TABLE.

Copy & Create Table Copy the schema or download it. Use with bq mk or run the DDL directly.

What It Does

No fluff, just useful stuff

1.
Two Output Formats JSON schema for bq command line, or DDL for direct execution
2.
Smart Type Mapping INT64, FLOAT64, BOOL, STRING, TIMESTAMP - it figures it out
3.
Nested Objects Turns nested JSON into STRUCT types automatically
4.
Arrays Handles arrays of primitives and arrays of objects
5.
File Upload Got a JSON file? Drag and drop it in
6.
Download Save as .json or .sql file. One click.

Use Cases

How data engineers use JSON to BigQuery Schema Converter

Saves Time

Writing BigQuery schemas by hand is tedious. Let the tool do it.

Gets Types Right

No more guessing between INT64 and FLOAT64. We detect it for you.

Handles Messy JSON

Nested objects, arrays, mixed types - it just works.

Your Data Stays Local

Everything runs in your browser. We never see your data.

Quick Answers

Stuff people actually ask

+Is this really free?

Yes. No catch, no premium tier. Just a tool that works.

+What's the difference between JSON Schema and DDL?

JSON Schema is for the BigQuery API (bq mk --schema). DDL gives you CREATE TABLE SQL you can run directly.

+Does it handle nested JSON?

Yep. Nested objects become STRUCT types. Works for any depth.

+What about arrays?

Arrays of primitives become REPEATED fields. Arrays of objects become ARRAY of STRUCT.

+Is my data sent to a server?

Nope. All conversion happens locally in your browser. Close the tab, it's gone.