Convert Nested API JSON Response to CSV Spreadsheet

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Upload a JSON file

The Challenge

REST APIs return nested JSON with objects inside objects, arrays of mixed types, and wrapper structures like { data: { results: [...] } }. Pasting this into a spreadsheet produces unusable single-cell output or [object Object] values. Developers and analysts waste time writing custom scripts to flatten each API's unique structure into tabular format.

How to save an API response as JSON

Browser: open DevTools Network tab, find the API request, right-click the response and select 'Copy response'. Paste into a text editor and save as .json
cURL: run 'curl https://api.example.com/endpoint > response.json' to save directly to file
Postman: send the request, click 'Save Response' and select 'Save as file'
JavaScript: use fetch() and write JSON.stringify(data) to a file or copy from console.log output
Python: use requests.get() and write response.json() to a file with json.dump()

Handling different JSON structures

Simple arrays are flattened directly — each array element becomes one CSV row. Nested objects become dot-separated columns: user.address.city. Primitive arrays (tags, categories) are joined with semicolons into a single cell. Object arrays are indexed: items[0].name, items[1].name — each sub-object gets its own indexed columns. The pivot down mode creates a field-per-row layout instead, useful for inspecting complex single records or building data dictionaries.

Flattened output vs raw JSON

Raw JSON: { "user": { "name": "Alice", "address": { "city": "NYC" } } } results in a single cell containing the entire object string or [object Object] in a spreadsheet.

Flattened CSV: Creates separate columns named 'user.name' and 'user.address.city' with values 'Alice' and 'NYC', allowing immediate sorting, filtering, and pivot table analysis.

Setting the correct root path

If your JSON is a plain array [...], leave root path empty — auto-detection handles it
If wrapped like { "data": [...] }, set root path to 'data'
If deeply wrapped like { "response": { "results": [...] } }, set root path to 'response.results'
If unsure, leave empty — the tool scans for the first array in the structure automatically
Incorrect root path shows 'Path not found' error — check your JSON structure and adjust

Step-by-Step Workflow

Upload JSON API Response File

Set Root Path For Wrapped Data

Configure Delimiter And Quote Styles

Review Flattened Columns In Preview

Download As CSV Or Excel File

Specifications

Input Format: JSON File
Array Detection: Auto-Detect
Root Path: Configurable
Nested Handling: Dot-Notation Flattening
Output Formats: CSV Or Excel

Best Practices

Leave root path empty for simple JSON arrays to enable auto-detection
Use semicolon delimiters when data contains commas in address fields
Manually concatenate paginated responses before processing single-page conversion

Frequently Asked Questions

How do I convert a JSON API response to CSV?

Save your API response as a .json file, upload it here, and set the root path to point to your data array (e.g. 'data' or 'results'). The tool flattens all nested objects into columns and outputs a clean CSV. Download as CSV or Excel.

What happens to nested objects in the JSON?

Nested objects are flattened using dot notation. A record like { user: { name: 'John', address: { city: 'NYC' } } } becomes columns: user.name and user.address.city. No nesting depth limit — all levels are flattened.

Can this handle paginated API responses?

It handles single-page responses. For paginated APIs, you need to combine all pages into one JSON array first (concatenate the data arrays), then upload. The tool processes whatever array you provide regardless of size.

What if different records have different fields?

The tool creates columns for every unique field across all records. Records missing a field get empty cells in those columns. This is standard CSV behavior — no data is lost from records with extra or fewer fields.

Is my API data safe?

Yes. Processing runs entirely in your browser. No data is uploaded to any server. This is important for API responses that may contain API keys, tokens, personal data, or proprietary business information.