Online Tool Store
Data Dictionary Generator
Paste CSV data and get an auto-generated data dictionary - inferred column types, null counts, unique values, and sample values - ready to copy or export as Markdown.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Data dictionary
| Column | Inferred type | Nulls | Unique | Sample values |
|---|
How it works
- Paste CSV data with a header row into the editor.
- Each column's values are scanned to infer a type — boolean, integer, number, date, or string.
- Null counts, unique value counts, and a few sample values are calculated per column.
- Copy the resulting table as Markdown to document your dataset elsewhere.
FAQ
How are column types inferred?
Each column's non-empty values are tested against boolean, integer, number, and ISO date (YYYY-MM-DD) patterns in order. If every value matches, that type is used; otherwise the column falls back to "string".
What counts as a null?
Any empty cell in a row for that column. The null count helps flag columns with inconsistent or missing data before you build a schema around them.
Can I export the result?
Yes — click "Copy as Markdown" to copy a ready-to-paste Markdown table, handy for READMEs, wikis, or pull request descriptions documenting a new dataset.
Is my data uploaded anywhere?
No — parsing and type inference both happen in your browser as you type or paste. Nothing is sent to a server.
How we compare
| Feature | Online Tool Store | Documenting columns by hand |
|---|---|---|
| Type inference from real data | ✓ | ✗ |
| Instant Markdown export | ✓ | Manual formatting |
Writing column documentation by hand is easy to let go stale. This tool reads the data itself, so the dictionary always reflects what is actually in the file.