# Data profiler — schema & quality report, no upload

> Profile a CSV, JSON, or Excel file: infer column types, null rates, cardinality, and duplicate estimates with a quality report. Runs in your browser, no upload.

Drop a CSV, JSON, or Excel file to inspect its schema — inferred column types, null rates, cardinality — with a data-quality report and duplicate estimates. The analysis runs on your device, so the file isn't uploaded.

Before you trust a dataset, you profile it: which columns are mostly empty, which are unique keys, where the types are inconsistent. This tool answers those questions in one pass so you don't discover a broken column halfway through analysis.

The quality warnings — high null rates, suspected duplicates, mixed types — point you straight to what needs fixing. From here, dedupe rows, scrub personal data, or query with SQL.

## How to

1. **Add a file.** Drop a CSV, JSON, or spreadsheet to profile.
2. **Review the schema.** See each column's inferred type, null rate, and distinct-value count.
3. **Read the warnings.** Check quality flags like high null rates and likely duplicates.
4. **Act on it.** Move to cleaning, deduping, or querying based on what you found.

## FAQ

### What does the profile tell me?

For each column: an inferred type, how many values are missing, how many are distinct, and quality warnings — the first thing to check before analysing an unfamiliar dataset.

### How big a file can it handle?

It previews with virtualization and computes stats locally, so sizeable files work within your device's memory rather than a server limit.

### Is my data uploaded to profile it?

No. Type inference and statistics are computed in your browser tab, so the rows stay on your device.


## Related tools

- [Row deduplicator](https://www.safepaper.app/data/dedupe)
- [PII scrubber](https://www.safepaper.app/data/pii-scrub)
- [SQL query](https://www.safepaper.app/data/sql-query)
- [Quick charts](https://www.safepaper.app/data/charts)

---

Canonical HTML: https://www.safepaper.app/data/profile
Markdown: https://www.safepaper.app/data/profile.md

There is no upload endpoint — your files are processed in this browser tab. Open your network tab and check.