API response debugging
You call an endpoint and get back hundreds of lines of JSON. BoltJSON shows the full schema instantly — every key, every type, every null — without scrolling through raw text.
Backend / API dev
Understand any JSON
in seconds.
Drop a file or paste JSON directly. See schema, types, null rates, sample values. Filter rows and export — everything local, nothing uploaded.
Drop your JSON file here
or click to browse · any size, processed locally
Loading engine…
- Auto schema & types
- Visual filter builder
- Null rates & samples
- Export CSV & JSON
- Zero uploads
Who uses BoltJSON — and why
Whether you work in IT, data engineering, backend or QA — there are moments every week where you receive a JSON you just need to understand fast.
Data quality checks
Before loading a dataset anywhere, you need to know: how many nulls, which columns are incomplete, are the types consistent. BoltJSON shows it in one screen.
Data Engineering
Config file review
Someone sends a deployment config or feature-flag export as JSON. Find a specific value fast, filter by key, see exact values, export only the fields you need.
DevOps / IT
Quick CSV conversion
You need the data in a spreadsheet — now. Drop the JSON, filter to the rows you want, pick the columns, export as CSV. No Python, no scripts, no waiting.
Analytics / Reporting
Test payload inspection
QA engineers and developers constantly deal with test fixtures and event payloads. Paste a payload from clipboard and immediately understand its structure.
QA / Testing
Preparing data for import
You have a JSON export from one system and need to import it into another — but only specific rows and columns. Filter, hide fields, export exactly the shape you need.
Data Migration
Frequently asked questions
Is BoltJSON free?
Yes, completely free. No account, no subscription, no credit card.
Does my JSON file get uploaded anywhere?
No. Everything runs inside your browser tab. Your file is read into browser memory, processed locally, and discarded when you close the tab. It never touches a server.
What file sizes are supported?
Any size. Files up to 200 MB work smoothly in most modern browsers. Performance beyond that depends on your device and available RAM.
What JSON shapes are supported?
Arrays of objects (most common), single objects, and nested structures. Nested objects are automatically flattened into dot-notation columns like user.address.city.
Can I use it without installing anything?
Yes. BoltJSON runs entirely in the browser — no install, no extension, no app required.