Resizer

A tiny macOS menu bar droplet for resizing photos, converting videos to GIF or animated WebP, and editing PDFs — built on sips (built into macOS), ffmpeg (Homebrew), optionally gifsicle (Homebrew) for lossy GIF compression, and Apple's PDFKit (no external tool) for PDFs.

One droplet, two apps: Resizer detects what you drop and routes it. Images and videos open the resize/convert options panel; PDFs open the PDF editor. A mixed drop opens both. Everything runs locally.

Usage

Drag photos or videos onto the ⤢ icon in the menu bar. An options panel appears:

• Images — scale by percent, fit within a box, or exact dimensions. The original resolution is always shown in the panel. "Scale by percent" shows a live "→ W × H px" readout of the final size. "Exact dimensions" opens pre-filled with the original resolution, keeps width/height locked to the original aspect ratio, and has a 1–100% scale slider. Output lands next to the original as name-<width>w-<random>.ext; originals and existing files are never replaced. Switch Output to "Ask for name…" to pick each output name in a save panel instead.
• Videos → GIF / WebP — pick an output Format (GIF or animated WebP), width, FPS (preset dropdown, 15 recommended), and for GIF the palette colors (fewer colors = smaller file). The panel shows the original video's file size, resolution, and duration, plus a live estimated output size that updates as you change settings (rough — expect real results within ~2× either way). WebP is typically several times smaller than GIF at the same resolution; use GIF only where the consumer requires it (e.g. GitHub READMEs).
  • Compression — None / Balanced (recommended) / Strong. For GIF this runs a gifsicle -O3 --lossy pass (30/80); Strong saves ~35% but can ghost on fast motion. For WebP it maps to quality q90/q75/q50. GIF compression needs gifsicle (brew install gifsicle) — without it, the dropdown defaults to None and conversion still works.
  • Max MB — Resizer re-encodes at smaller widths until the output fits under that size — handy for Slack/email limits.
  • Trim — single-video drops show an inline muted preview with a two-handle range slider. Dragging a handle seeks the preview to that frame, Play replays exactly the selected range, and the size estimate tracks the shortened clip. Leave the handles at the ends to export the full video.
  • Speed — a slider from 25% to 400% (100% centered) speeds up or slows down the export. The muted preview plays back at the chosen rate so what you see matches what you get, and the size estimate tracks it (2× speed ≈ half the frames).
  • Crop — single-video drops: toggle Crop, then drag a box over the preview to export just that region. A crop is a true crop, not a resize — the output is exactly the drawn box at the video's native resolution, so the Width and Max MB fields are disabled while a crop is set. Clear removes it; Esc leaves crop mode but keeps the box.

Drop one or more PDFs instead and the PDF editor opens:

• Combine — dropping several PDFs concatenates them into one working document, in drop order.
• Add PDF/Image — the toolbar button opens more PDFs or images while you work; their pages are appended to the bottom of the list (each image becomes a one-page document). Undoable like any other edit.
• Thumbnails + preview — a scrollable page-thumbnail sidebar sits beside a full-page preview. Selecting a thumbnail scrolls the preview to it, and scrolling the preview highlights the matching thumbnail, so you can verify you're on the right page and see the reassembled document as you go.
• Rotate / Delete / Extract — act on one page or a multi-selection. Rotate turns the selected pages ±90° (a badge shows the applied rotation); Delete removes them; Extract… saves the selected pages as a new PDF via a save panel, leaving the working document untouched.
• Reorder — drag thumbnails to change page order; dragging to the top or bottom edge of the sidebar auto-scrolls, so you can move a page any distance. Each thumbnail also has an editable page-number field — type a new number (e.g. change 13 to 1) and confirm with Return or the ✓ button beside the field, and the page jumps to that position, pushing the rest down.
• Redact — toggle Redact and drag black boxes over anything sensitive (draw as many as you like; Esc or toggling off exits). On Export/Extract, any page carrying a redaction is flattened to a 144-DPI image with the boxes baked in, so the text and vector content underneath is gone — not just hidden (it cannot be selected, copied, or recovered). Pages without redactions stay as vector, so flattening only happens where needed. Use Clear Redactions to remove the boxes on the selected pages; ⌘Z / Revert work too. The on-screen boxes before export are a reversible preview; only the exported file is flattened.
• Undo / Revert — ⌘Z (or the Undo button) steps back through edits; Revert returns to the pages as originally dropped.
• Export… — writes the reassembled document to a filename you choose (defaults to name-edited-<random>.pdf). The export is built fresh from the original files, so source PDFs are never modified, and Resizer refuses a name that would overwrite a source.

Password-protected PDFs prompt for the password on open; encrypted or unreadable files in a multi-drop are skipped with a note. PDF editing is page-level, so interactive form fields, outlines, and internal links are not carried into the exported document.

You can also drop files onto the app icon in Finder, use "Open With → Resizer", or pick Load File… from the menu bar menu. About Resizer in the same menu shows the version, build number, and a changelog generated from git history at build time.

Build & install

./build.sh            # builds build/Resizer.app
./build.sh install    # builds and copies to /Applications

When building inside a git clone, build.sh stamps the build number (CFBundleVersion) with the git commit count and generates the About window's changelog from git log; outside a clone both steps are skipped.

Requires Xcode command line tools (swiftc) and ffmpeg (brew install ffmpeg). Image resizing works without ffmpeg. Lossy GIF compression additionally uses gifsicle (brew install gifsicle).

To launch at login: System Settings → General → Login Items → add Resizer.

Tests

tests/run_tests.sh    # unit tests (sizing math) + integration (real sips/ffmpeg runs)

Layout

• Sources/Geometry.swift — pure sizing math (percent/fit/exact/max-width, GIF shrink-to-target stepping, collision-free output naming)
• Sources/ToolRunner.swift — Process wrapper + Homebrew-aware binary lookup
• Sources/ImageProcessor.swift — sips pipeline (copy, then resample the copy)
• Sources/GifProcessor.swift — ffmpeg two-pass palette GIF encode (inter-frame optimized) with optional gifsicle lossy pass, animated WebP encode, output size estimator, and target-size retry loop
• Sources/VideoProbe.swift — AVFoundation metadata loader (resolution, duration, file size) behind the panel's original/estimate labels
• Sources/DropView.swift / AppDelegate.swift — status item + drag & drop; classifies each file as image / video / PDF and routes it
• Sources/OptionsWindowController.swift — the options panel
• Sources/VideoTrimView.swift — inline video preview + trim controls for single-video drops
• Sources/TrimRangeSlider.swift — custom two-handle range slider (AppKit has no native one)
• Sources/PdfEditModel.swift — pure page-list editing logic (combine, reorder, rotate, delete, extract refs, undo/revert), fully unit-tested
• Sources/PdfAssembler.swift — PDFKit plumbing: load, copy pages, assemble a fresh document, thumbnails, and secure flatten-on-export of redacted pages
• Sources/PdfRedactOverlayView.swift — transparent capture layer for drawing redaction boxes over the preview (view→page coordinate conversion)
• Sources/PdfThumbnailListView.swift — NSCollectionView thumbnail sidebar with multi-select, drag-reorder, and lazy off-main thumbnail rendering
• Sources/PdfEditorWindowController.swift — the PDF editor window (sidebar + PDFView preview, toolbar operations, export/extract)
• Sources/AboutWindowController.swift — About window (version, changelog, link)
• Resources/AppIcon.png — app icon source; build.sh scales it into the .icns

App icon: Resize by Icons8.