LeanRows

Native Windows x64 · Read only

Large row files, kept lean.

LeanRows opens the rows you need without turning the entire file into an in-memory workbook. It is a focused desktop viewer for CSV, TSV, JSONL, NDJSON, log, and text files.

Search literal values inline, jump to an absolute row, and copy bounded selections while the source remains read only.

Get the latest Windows build

v0.1.3 is an unsigned Windows x64 ZIP. Verify the accompanying .sha256 file before running it.

Architecture model
Only a bounded row window is decoded for display. This is an explanatory diagram, not an application screenshot.
LocalNo upload path
Read onlySource stays untouched
NativeWin32, no embedded browser
Open sourceMIT licensed

Redesigned native interface

Full rows. A calmer frame.

LeanRows v0.1.3 keeps the virtual owner-data grid below a responsive top bar with file context, inline search, and direct actions. System follows the active Windows app theme, while the appearance button cycles through System, Light, and Dark. Indexing progress uses a flat two-DIP accent rule, and Windows high contrast uses system colors. The image below is an exact 1180×720 capture of the frozen v0.1.3 release executable in Light appearance. It uses only synthetic data from operations-sample.csv: all 120 rows across six fields are indexed, and the status reads Ready | 120 rows | 7600 / 7600 bytes | 100%. The binary and fixture were unchanged, the saved System preference was restored, and the application closed cleanly.

LeanRows v0.1.3 frozen Windows release in Light appearance showing the fully indexed 120-row synthetic operations-sample.csv across six fields with Ready and 100 percent status
Real application capture. Frozen v0.1.3 x64 build · Light appearance · synthetic fixture · native owner-data grid

Progressive by construction

See useful rows while indexing continues.

The source file remains the backing store. LeanRows reads positioned blocks, records compact checkpoints, and reconstructs only the viewport requested by the native list view.

01
OpenExplicit local file, read-only handle
02
ScanPositioned 64 KiB blocks
03
IndexBounded adaptive checkpoints
04
RenderImmutable viewport cache

Purposefully narrow

The right viewing model for each row format.

LeanRows does not infer spreadsheet types or silently treat the first row as a header. It displays the structure that is present in the file.

CSV

Quote-aware logical records and independently bounded tabular fields.

.csv

TSV

Tab-delimited rows presented as native, resizable columns.

.tsv

JSON lines

One physical row at a time, without constructing a document-wide tree.

.jsonl · .ndjson

Logs & text

Line-oriented viewing with bounded previews and visible invalid bytes.

.log · .txt

Limits are features

Memory behavior is explicit in the implementation.

64 KiB
positioned read buffer
4,096
checkpoint capacity before adaptive thinning
128
rows in one viewport request
512 KiB
maximum viewport payload

These are code-level capacities, not benchmark claims. Fields, previews, queues, and operation scratch space are also bounded so a large source does not authorize a proportional allocation.

A smaller attack surface

A viewer that behaves like a viewer.

File content is untrusted and remains inert. LeanRows does not execute formulas, ANSI sequences, HTML, paths, or URLs found in a row.

  • 01

    Offline by design. No telemetry, account, cloud service, or network file path.

  • 02

    Local regular files only. UNC, remote, device, and reparse-point sources are rejected.

  • 03

    Snapshot integrity. Source identity and revision evidence are checked while work proceeds.

  • 04

    Visible damage. Invalid bytes are escaped and oversized display values are marked as truncated.

  • 05

    No write path. Editing, saving, transformation, macros, plug-ins, and scripts are outside v0.1.

Evidence before adjectives

The release is built around reproducible checks.

Every tagged build must pass formatting, workspace tests, strict Clippy, native-control smoke tests, deterministic packaging checks, and the final checksum contract on the pinned Rust toolchain.

The frozen local v0.1.3 candidate passed 25/25 aggregate checks against its exact release binary, including document, random-seek, sparse logical-scale, source-preservation, network-observation, and whole-process-tree memory checks. The tagged release workflow separately verifies the release commit, rebuild, quality gates, package checksum, and published assets; the local receipt is not a substitute for that tagged proof.

Inspect the QA harnesses

Before installing v0.1.3

The Windows build is intentionally unsigned.

Windows may display a SmartScreen warning. Download the ZIP and its matching SHA-256 sidecar from the same GitHub Release, then compare the published value before running or installing LeanRows. 

Get-FileHash .\LeanRows-v0.1.3-windows-x64-unsigned.zip -Algorithm SHA256

Installation is per-user and requires no administrator access. Protected Windows choices are preserved; direct defaults are recorded and changed only where no protected choice exists.