Leano

Batch convert images to WebP/AVIF — fully local, no server, no API calls.

Docs and web app: leano.dev

npx leano-cli ./public --format webp --quality 80 --max-width 1920

Recursively scans a directory, converts every .jpg, .jpeg, .png to WebP and/or AVIF using sharp, preserves the full folder structure, and reports per-file savings.

Install

npm install -g leano-cli
# or run without installing:
npx leano-cli <input> [options]

Usage

leano-cli <input> [options]

Arguments:
  input                   Directory of images to convert

Options:
  -f, --format <format>   Output format: webp | avif | both  (default: webp)
  -q, --quality <number>  Compression quality 1–100          (default: 80)
  --lossless              Lossless compression
  --max-width  <px>       Maximum output width  (no upscaling)
  --max-height <px>       Maximum output height (no upscaling)
  -o, --out <path>        Output directory      (default: <input>-optimized)
  --in-place              Replace source directory safely via temp dir
  -c, --concurrency <n>   Parallel jobs (default scales with CPU; cap webp 16 / both 12 / avif 8)
  --quiet                 No per-file rows (spinner + summary only)
  --dry-run               List planned outputs only
  -h, --help              Show help
  -V, --version           Show version

Examples

# WebP at quality 80 (default)
leano-cli ./images

# Both WebP + AVIF
leano-cli ./images --format both --quality 75

# Resize + convert
leano-cli ./public/photos --format webp --max-width 1920 --quality 85

# Lossless WebP
leano-cli ./assets --format webp --lossless

# Custom output directory
leano-cli ./src/images --format avif --out ./dist/images

# Overwrite source in-place (safe: uses temp dir, rolls back on failure)
leano-cli ./public --format webp --in-place

Output

leano-cli v1.0.2
  Input:   /home/user/project/public/images
  Output:  /home/user/project/public/images-optimized
  Format:  both  Quality: 80
  Files:   42 images found → 84 outputs

File                                        Original    Converted     Savings
─────────────────────────────────────────────────────────────────────────────
  hero.webp                                     1.2 MB       149 KB         88%
  hero.avif                                     1.2 MB       218 KB         82%
  icons/logo.webp                                45 KB        12 KB         73%
  icons/logo.avif                                45 KB         9 KB         80%
  ...
─────────────────────────────────────────────────────────────────────────────

✔ 84 files converted
✔ 56.2 MB → 9.1 MB (84% saved)

Output: /home/user/project/public/images-optimized

Behavior

| Extension | Action | |------------------|-------------------------------| | .jpg / .jpeg | Re-encoded via sharp | | .png | Re-encoded via sharp | | .webp / .avif| Copied as-is (no re-encoding) |

--in-place safety

1. All files are written to a temporary directory first.
2. Only if every conversion succeeds, the source directory is replaced atomically.
3. On any failure the source is left completely untouched and the temp dir is cleaned up.

Exit codes

| Code | Meaning | |------|--------------------------| | 0 | All files processed OK | | 1 | One or more files failed |

Project structure

src/
  index.ts    Entry point & orchestration
  cli.ts      Argument parsing (commander)
  scan.ts     Recursive directory traversal
  convert.ts  worker-thread pool (one sharp pipeline per core slot) + job scheduling
  workers/    encodeWorker.ts + encodePool.ts — parallel Node workers for CPU-bound encode
  writer.ts   Output & in-place replacement logic
  logger.ts   Table, summary, formatting helpers
  types.ts    Shared TypeScript types

Requirements

• Node.js ≥ 18
• Runs on Linux, macOS, Windows (sharp ships pre-built binaries)