XLSX Toolkit

xlsx-toolkit

Single Rust binary with five subcommands, built on umya-spreadsheet (read+write) and clap. The skill directory is a cargo project — source in src/, binary at bin/xlsx-toolkit.

First-time setup

Invoke via the shim, which picks a prebuilt for the current platform or builds from source on first use:

~/.claude/skills/xlsx-toolkit/bin/xlsx-toolkit --help

The skill ships a prebuilt only for aarch64-apple-darwin. On any other platform the shim runs cargo build --release once and caches the result in target/release/. Subsequent runs go straight to the cached binary — no cargo overhead.

Optional alias if you'll use this often:

alias xlsx-toolkit='~/.claude/skills/xlsx-toolkit/bin/xlsx-toolkit'

macOS Gatekeeper: if the bundled binary arrived with a com.apple.quarantine xattr (downloaded .skill), the shim strips it automatically. If macOS still blocks it ("unidentified developer"), run xattr -dr com.apple.quarantine ~/.claude/skills/xlsx-toolkit/bin and retry.

The rest of this file assumes you can invoke the binary as xlsx-toolkit. If the alias isn't set, use the full path.

When to use what

For anything else, read references/patterns.md — it covers formulas vs cached values, dates, merged cells, multi-row headers, hidden sheets, write-side details, and how to drop down to the umya-spreadsheet API when the subcommands don't fit.

Workflow

1. Always inspect first. Run xlsx-toolkit inspect <file> before doing anything else. It prints sheet names, dimensions, headers, formula count, merged ranges, and a sample. Without this, you'll guess wrong about what's in the workbook.
2. Convert to CSV when piping to other tools. to-csv --sheet NAME to stdout is the right move when feeding data to jq, grep, awk, csvkit, etc. Don't try to parse xlsx with shell.
3. For new workbooks, prefer write over hand-rolling. It handles freeze panes, autofilter, column widths, and formulas through a JSON spec. If the layout is unusual, fall back to writing a small cargo binary against the patterns in references/patterns.md.
4. Coverage is the data-quality lens. Use coverage to find columns that are mostly empty (often imported-but-unused fields) or to confirm a migration populated what it should. The HubSpot data-model coverage doc in this monorepo is exactly this shape.

Quick examples

Inspect

xlsx-toolkit inspect ./data.xlsx --sample 5
xlsx-toolkit inspect ./data.xlsx --json | jq '.details[].headers'
xlsx-toolkit inspect ./data.xlsx --sheet Contacts

Convert

# One sheet → stdout (pipe to anything)
xlsx-toolkit to-csv ./data.xlsx --sheet Contacts | head

# All sheets → sibling .csv files next to the source
xlsx-toolkit to-csv ./data.xlsx

# TSV
xlsx-toolkit to-csv ./data.xlsx --sheet Contacts --delimiter $'\t'

Write

cat > /tmp/spec.json <<'EOF'
{
  "sheets": [{
    "name": "Report",
    "headers": ["Item", "Qty", "Price", "Total"],
    "rows": [
      ["apples", 3, 1.5,  { "v": 0, "f": "B2*C2" }],
      ["bread",  2, 4.25, { "v": 0, "f": "B3*C3" }]
    ],
    "freeze_header": true,
    "autofilter": true,
    "column_widths": [12, 6, 8, 10]
  }]
}
EOF
xlsx-toolkit write --spec /tmp/spec.json --out report.xlsx
# Or pipe the spec on stdin:
cat /tmp/spec.json | xlsx-toolkit write --out report.xlsx

Cell values: plain JSON string | number | boolean | null for static data, or { "v": <value>, "f": "FORMULA", "t": "n|s|b" } for formulas / explicit types. Set the value AND the formula together — the cached v is what other tools see until Excel re-evaluates.

Diff

# Positional row diff (row N vs row N) across shared sheets
xlsx-toolkit diff before.xlsx after.xlsx

# Key-based: match rows by a header column value (stable across reorderings)
xlsx-toolkit diff before.xlsx after.xlsx --key "Property"

# Restrict to one sheet, JSON output
xlsx-toolkit diff before.xlsx after.xlsx --sheet Contacts --json

Coverage

# Per-column fill % on every sheet
xlsx-toolkit coverage ./data.xlsx

# Only columns with ≥50% fill
xlsx-toolkit coverage ./data.xlsx --threshold 0.5 --sheet Contacts

Output conventions

• Human-readable goes to stdout; pass --json (where supported) for machine output.
• Status lines from write and to-csv (file-writes) go to stderr, so stdout stays clean for piping.
• All subcommands exit non-zero on usage errors and propagate anyhow errors with context on failure.

When NOT to use this

• Inside a Rust crate that already depends on umya-spreadsheet or calamine. Use the in-tree dep directly — don't shell out to global binaries for production logic.
• For .xls (old binary format) — umya is xlsx-only. Convert first (libreoffice --headless --convert-to xlsx file.xls) or read it elsewhere.
• For .xlsm macros — umya reads the data but doesn't preserve macros on write. Don't round-trip a macro-enabled workbook through write.
• For 100k+ row workbooks — umya is fine but loads everything into memory. If memory is tight, dump to CSV and stream from there, or write a one-off using calamine (much faster reader, read-only).

Project layout

~/.claude/skills/xlsx-toolkit/
├── SKILL.md
├── Cargo.toml
├── .gitignore                            ← /target/ and *.skill ignored
├── references/
│   └── patterns.md                       ← gotchas, advanced usage, umya API notes
├── src/
│   ├── main.rs                           ← clap entry point
│   └── commands/
│       ├── mod.rs
│       ├── common.rs                     ← shared read/walk helpers
│       ├── inspect.rs
│       ├── to_csv.rs
│       ├── write.rs
│       ├── diff.rs
│       └── coverage.rs
├── bin/
│   ├── xlsx-toolkit                      ← shell shim, dispatches to prebuilt or cargo build
│   └── aarch64-apple-darwin/
│       └── xlsx-toolkit                  ← shipped prebuilt (~4 MB)
└── target/release/xlsx-toolkit           ← cargo-built fallback (gitignored)

To add another platform: rustup target add <triple>, cargo build --release --target <triple>, then copy target/<triple>/release/xlsx-toolkit to bin/<triple>/xlsx-toolkit. The shim picks it up automatically. For Linux targets from a Mac, use cross (cross build --release --target x86_64-unknown-linux-gnu) to get the right glibc.