17 annotation types
Lines, arrows, rectangles, circles, polylines, polygons, freehand pen, curves, callouts, clouds, text, and stamps — every tool with line type, color, opacity, and end-decoration controls.
Native macOS · Built for AEC
Caliper is a fast, focused PDF viewer and markup app designed for people who measure things. Calibrate scale, take off areas, drop stamps, redline plans — and keep every line as crisp vector data from drawing to save.
Generic PDF readers treat construction drawings like documents. Caliper treats them like drawings: scale-aware measurement, snap-to-geometry precision, vector-clean edits, and a markup suite engineered around the tools you'd reach for on a hard copy — pencils, scales, stamps, and a redline pen.
Lines, arrows, rectangles, circles, polylines, polygons, freehand pen, curves, callouts, clouds, text, and stamps — every tool with line type, color, opacity, and end-decoration controls.
Per-page scale calibration with smart distance parsing (feet-inches, fractions). Linear, polyline, area, and angle dimensions in seven display formats — decimal inches all the way through millimeters.
Drag a rectangle around a printed scale legend ("1/4″ = 1'-0″") and Caliper reads it with on-device Vision OCR, sets the scale for that page, and quietly gets out of your way.
Optional grid overlay with customizable spacing, color, and opacity. Grid Snap (G) and Object Snap (O) lock drawing tools to grid intersections and the underlying vector geometry of the PDF itself.
Twelve built-in standard stamps plus a custom stamp library — import any single-page PDF as a reusable stamp. Vectors stay vectors through every save cycle.
Drop a callout box with perpendicular leader geometry, then right-click to add as many extra leaders as you need. Each leader is independently editable.
Open two documents side-by-side, scroll and zoom in lockstep. Compare revisions, cross-reference details, drag pages between tabs — without switching windows.
Marquee any region, then delete it from the PDF — or cut it to the clipboard as a vector PDF and paste it back as a stamp. No rasterization, no blurry zoom.
Every drawing tool you'd expect from a redline workflow, with the style controls of a vector editor. Tools snap, dimensions update live, and a multi-select inspector only touches the properties you actually change.
Scale calibration is per-page, so a set with mixed scales doesn't fight you. Caliper parses every architect's shorthand — fractions, feet-inches, decimal feet, metric — and converts cleanly between them.
Tabs, sidebars, and auto-save that write your markups straight into the PDF — one file, no loose attachments — and keep every annotation fully re-editable each time you reopen it.
Twelve standard construction stamps ready to go — APPROVED, REJECTED, DRAFT, REVISED, and more. Need your own? Import any single-page PDF and it's a stamp.
Available on the Mac App Store. Free trial — purchase to unlock saving.
Get it on the Mac App Store