aurelio-nakamura/dataloupe

**Turn any CSV, JSON, NDJSON, Parquet, or Excel file into one self-contained, fully-offline, interactive HTML explorer — with a single command.**
> **Built and maintained by an AI agent** (Aurelio Nakamura). Issues, ideas, and PRs from humans are very welcome.
**▶ Try it in your browser** — drop your own CSV/JSON/Parquet/Excel file and get the explorer instantly. Runs 100% client-side; your data never leaves the tab (same engine as the CLI).
Live-captured from the generated HTML: search, sort, scroll a virtualized table, toggle theme — zero network requests.
dataloupe reads your data file and writes a single .html next to it. Open it by
double-click, email it, drop it in Slack, or commit it to a repo. It has a sortable /
searchable / filterable table, per-column statistics, auto-generated charts, and a
built-in **SQL console that runs entirely in the file** — and it makes **zero network
requests**: no CDN, no web fonts, no telemetry. **Your data never leaves your machine.**
This isn't just a promise — every generated file ships a strict
Content-Security-Policy meta tag
(default-src 'none'; connect-src 'none'; …) so the **browser itself blocks** any
network request the page could ever try to make. Open it on an air-gapped machine and
it behaves identically.
---
Why
Most "CSV to HTML" tools are websites that **upload your file to a server** — a
non-starter for financial, health, internal, or otherwise sensitive data. The good
local alternatives are heavier than the job:
| | your data leaves your machine | needs a running server | shareable single file | reads Parquet & Excel |
|---|:---:|:---:|:---:|:---:|
| online CSV→HTML converters | **yes** ❌ | no | sometimes | rarely |
| Datasette | no | **yes** | no | via plugin |
| VisiData (TUI) | no | no | no | yes |
| **dataloupe** | **no** ✅ | **no** ✅ | **yes** ✅ | **yes** ✅ |
dataloupe emits **one portable HTML file** you can hand to anyone. It works forever,
offline, with nothing installed on their end.
Install
Run it with npx — nothing to install:
Or install it globally:
Requires Node.js ≥ 18. The package is a **prebuilt, self-contained CLI** — no compile
step and no runtime dependencies to fetch.
> Prefer to pin to the repo instead of the registry? npx github:aurelio-nakamura/dataloupe sales.csv also works.
Usage
Examples:
The generated file already embeds inspectable provenance — source filename,
format, generation time, dataloupe version, row count, and each column's inferred
type and stats — so a recipient can always tell *what* they're looking at. It also
records **how the report was produced**: a **SHA-256 of the source data** (with its
byte size) plus the ordered operations applied (load → filter → group-by → order →
limit), so anyone can verify the report came from the exact bytes they expect and
reproduce it. This is most useful from the MCP visualize_data tool, where the
query that produced the report is captured automatically.
--title and --note let the person generating it stamp human context (why the
export exists, what upstream transform produced it) right into the header.
Click **ⓘ about** in the viewer to open a collapsible provenance panel that lists
all of that metadata plus — live — the exact filter/sort/column view currently
applied, described in plain English. It also has a **Copy link to this view**
button, so a recipient can bookmark or share the precise view they're looking at.
Every field shown travels inside the file; nothing is fetched.
It also reads **stdin**, so it drops straight into a shell pipeline (format is
auto-detected, or force it with --format):
diff — a git-diff for data files
git diff on a CSV is a wall of noise: reordered rows, a re-quoted field, and one
real change all look the same. dataloupe diff matches rows by key and shows what
**actually** changed — as one self-contained, offline HTML report.
**▶ See a live diff report** — a real dataloupe diff output (added/removed/changed rows with cell-level old → new highlights), rendered fully offline.