sheetsift

Read Excel files without opening Excel.

Opening a spreadsheet just to look something up means waiting for a heavy application to start, loading the whole workbook into memory, and risking an accidental edit to a file you only wanted to read. sheetsift is the read-only alternative: open a large xlsx or csv and get sorting, filtering and search that stay fast on sheets that make Excel crawl.

• Read-only. The source file is never written to.
• Fast on large sheets. Sorting and filtering stay responsive where a spreadsheet application stalls.
• Private. In the browser the data never leaves it — there is nowhere to send it. The desktop build talks to no network at all.
• Two builds, one core. A desktop app (tauri) and a browser app (wasm) run the same code.

Why it is fast

An xlsx is XML inside a zip, which cannot be queried directly at speed. The sheet is converted once into SQLite; repeated strings are interned into a dictionary, so sorting and filtering reduce to integer comparisons.

A converted sheet can be kept as a .sift file and reopened without converting again. It is password-sealed by default, because a sheet may contain people's names.

Running it

In a window:

npm run dev:tauri

In a browser:

npm run dev:web

The UI is the same one. Exactly one thing differs: the window takes the path returned by the operating system's file dialog and reads it directly, instead of routing the bytes through the UI. Drag-and-drop is bytes on both platforms.

Pick a file and it is converted to SQLite right there, then queried by sorting, value selection and search. How many header rows there are is specified by the user in the controls.

The distributable builds are npm run build:tauri and npm run build:web. docs/desktop.md lists what baking the desktop build requires, and docs/wasm.md what the browser build requires (clang and wasm-bindgen-cli).

Tests

npm run ci

That one command is the gate.

Using it as a library

The viewer is built on sheetsift-core, which takes bytes and returns bytes and knows nothing about tauri or the file system. Integrating it in another application — the crate layout, the feature gates, the .sift format, the keys the caller has to inject, and what the gate does and does not cover — is documented separately in docs/core.md.