ItsPaint

MS Paint for the Mac. Paste a screenshot, number the steps, drag it out.

Preview markup has no step badges, no pixelate and no drag-out.

3.17 MB · free on the App Store · MIT · no network entitlement, so the kernel refuses a socket

brew install --cask joshlin2201/itspaint/itspaint

Download the disk image · Mac App Store · macOS 14+, universal

What makes it different

• 3.17 MB, and a window on screen in half a second. Krita is a gigabyte and built for painters. CleanShot X is $29 plus a cloud subscription. Preview is already on your Mac and will not number a step or pixelate a token.
• No network entitlement. com.apple.security.network.client is not requested, so the kernel will not open a socket for it. Three commands to check that yourself.
• Background removal with no ML model and nothing to download. Four corner-seeded flood selections, unioned. Thirty lines of code.
• The drawing engine has no UI. Packages/PaintKit imports Foundation, CoreGraphics, ImageIO, CoreText and UniformTypeIdentifiers, and nothing else, so swift test verifies most changes with no Xcode. It is also a package you can depend on.
• Free, MIT, and it stays that way. There is no account and no telemetry.

Paste the screenshot, number the steps, crop it, drag it out, close the window. Nothing lands on your Desktop.

PaintKit as a dependency

The engine is its own SwiftPM product, so you can draw, key out a background or encode a PNG with none of the app around it. No AppKit, no third-party dependency, macOS 12 and up.

.package(url: "https://github.com/joshlin2201/itspaint", from: "0.16.4")

Those two are served from the Swift Package Index's own API rather than written here, so they report what it built, on a machine that is not mine, and they go red without anybody having to notice. The same page records zero data-race-safety errors — every target in both manifests is swiftLanguageMode(.v6), so strict concurrency is on and nothing is waived.

The macOS 12 is deliberate. The app needs macOS 14; the engine does not and no longer says it does. It had the app's number by inheritance rather than by need, and a floor is not a warning a consumer can ignore — SwiftPM refuses to resolve at all when a dependency's deployment target is above yours.

PaintKit gets you a product shot off its page in four lines, on device, with no model and no network:

import PaintKit

let engine = PaintEngine(canvas: try ImageCodec.decode(contentsOf: input))
guard engine.removeBackground() else { fatalError("no background to remove") }
try ImageCodec.encode(engine.canvas, as: .png).write(to: output)

Those four lines are compiled on every push, by a CI job that builds them from a package outside this repository — the one that declares macOS 12, so the floor above cannot quietly rise. And the result is checked by counting transparent pixels rather than by whether the program exited quietly: on a 60px mark centred on a 400×400 page the count goes from 0 to 156,400, which is 160,000 minus the 3,600 pixels of subject, asserted for six subject sizes.

If you do depend on it: it ships often while it is in beta, and until 1.0 a minor version may still carry a breaking change to the document format — CHANGELOG.md says so at the top. Watch ▸ Custom ▸ Releases is the notification for that one thing. Watching the repository outright also mails you every issue and every comment, which is why most people do not.

What it does

Marking up

Step badges	1, 2, 3… auto-numbered, numeral auto-contrasted, and the sequence can start anywhere for a run that spans two screenshots.
Arrows and callouts	A draws an arrow. Fifteen shapes in all, solid, dashed or dotted, outlined or filled.
Highlighter	Its own ink, kept apart from the colour pair. Overlapping passes in one stroke never darken.
Pixelate	A mosaic over the part you would rather not publish. Block size 4–48.
Spotlight	Drag a box and everything outside it dims, so the eye lands where you meant it to.
Text with a rim	One colour cannot stay legible across a light panel and a dark one, so annotation text carries a contrasting edge.

Getting things in and out

Drag straight out	Into any app that takes an image. No save panel, and no Screenshot 2026-08-07 at 11.42.13.png left behind.
Paste onto anything	It arrives floating. Bigger than the canvas and the canvas grows rather than cropping it.
Nine export formats	PNG, JPEG, TIFF, BMP, GIF, HEIC, AVIF, PDF, ICO. Formats without alpha flatten onto Colour 2, not onto black.
Open With	Registered for PNG, JPEG, TIFF, BMP, GIF and HEIC.

Remove a background with no model and no network

One command. It floods from all four corners and makes the union transparent. If the page is not actually separable it says so and changes nothing.

It knows what a page is, not what a subject is, so it works on logos, product shots and scanned diagrams. It is useless on hair.

How it works, in thirty lines of code →

Painting

Thirteen tools	Pencil, brush, highlighter, eraser, clone, shape, text, badge, fill, eyedropper, select, pixelate, spotlight. One rail button each, every one a single key.
Four brush nibs	Round, square, soft, and spray. Spray keeps spraying while you hold still, which is the whole feel of an airbrush.
Four ways to select	Rectangle, ellipse, lasso, and Instant Alpha. Marching ants follow the pixel mask rather than its bounds.
Pixel control	Pointer-centred zoom, nearest-neighbour above 100%, a pixel grid, live tool footprints, rotate by any angle.
Snap to grid	⇧⌘' at 8–64px for shapes, selections and pasted content. Freehand ignores it.

Thirteen tools, fifteen shapes, and a transparent canvas. The window above is ItsPaint painting, not marking up.

Install

brew install --cask joshlin2201/itspaint/itspaint

Or take the disk image, open it and drag ItsPaint to Applications. It is also free on the Mac App Store.

It ships often while it is in beta. Watch ▸ Custom ▸ Releases is the quietest way to hear about a new build.

Requires	macOS 14 Sonoma or later
Architecture	universal, one build for Apple silicon and Intel
Signing	Developer ID, notarised, ticket stapled to the image and the app, so the check needs no network and there is nothing to clear from the Terminal
Download	3.17 MB for the disk image, with a SHA-256 in checksums.txt

shasum -a 256 -c checksums.txt
xcrun stapler validate ItsPaint-*.dmg

If macOS asks you to confirm the first launch, open System Settings ▸ Privacy & Security and click Open Anyway. Why that happens.

No network. Three commands to prove it

This is a property the kernel enforces, not a promise anyone is making. The first two commands run against the copy in /Applications, the third greps this repository:

codesign -d --entitlements - --xml /Applications/ItsPaint.app | plutil -p -
otool -L /Applications/ItsPaint.app/Contents/MacOS/ItsPaint
grep -rniE 'URLSession|NWConnection|import Network|CFSocket' App Packages

Command	What comes back
codesign	Three entitlements: sandbox, files you pick in a panel, app-scoped bookmarks. No network.client and no .server, so the kernel will not open a socket for it
otool	Apple frameworks and the Swift runtime, on both architectures. No CFNetwork, no Network.framework, no bundled dylib
grep	Nothing. Package.swift also declares no dependency, so there is no third-party code behind it

The entitlements check goes first because it is the one that holds even if the developer is lying to you. It reports what the kernel will permit.

Why that order, and how to make the same claim falsifiable in your own app →

Contributing, and the engine needs no Xcode

Because PaintKit has no UI, most changes to how ItsPaint draws can be made and checked with a text editor and a terminal. No simulator, no GUI session, no Xcode project:

git clone https://github.com/joshlin2201/itspaint.git
cd itspaint
swift test          # the whole engine suite, in a fresh clone

Seven issues are open and labelled good first issue, each naming the file and the line to start at. They sit in three different parts of the app so you can pick whichever suits you:

View layer, AppKit drawing, no engine knowledge needed

• #11 A loupe that follows the pointer

Engine, pure functions over pixels, no Xcode needed

• #12 Brightness, contrast and saturation
• #5 Arrowheads as a line style, not a separate shape

Selection arithmetic, also engine-only

• #3 Grow and shrink a selection by a pixel amount
• #4 Make a selection from the alpha channel
• #6 Flip and rotate the selection, not the whole image
• #7 Add to and subtract from a selection

CONTRIBUTING.md covers the structure, the design constraints, and what a change has to prove before it lands.

Tools and shortcuts

Group	Tools
Draw	Pencil, Brush (round / square / soft / spray), Highlighter (own ink, four colours), Eraser, Clone (clone / soften)
Insert	Shape, Text, Step Badge, Fill, Eyedropper
Select	Rectangle, Ellipse, Lasso, Instant Alpha
Effects	Pixelate, Spotlight

Thirteen rail buttons. Variations live inside the tool that owns them, so there are fifteen shapes behind Shape, four nibs behind Brush and four modes behind Select. The whole set stays available without a button each.

Shortcut	Action	Shortcut	Action
P	Pencil	B	Brush
H	Highlighter	E	Eraser
C	Clone	F	Soften
U	Shape	T	Text
N	Step Badge	K	Fill
I	Eyedropper	M	Select
R	Pixelate	S	Spotlight
X	Swap colours	[ / ]	Change tool size
Space	Pan	Esc	Cancel what you are doing
⌥1–⌥9	Choose a shape	⇧⌘'	Snap to grid
⌘K	Crop to selection	⌘9	Fit to window
⇧⌘E	Export	⌘V	Paste as a floating image

Pinch or ⌘-scroll to zoom around the pointer. Hold ⌥ to sample a colour without changing tools. Right-drag uses the second colour. Esc cancels the current shape, text box, selection, floating paste, or options panel.

Instant Alpha selects connected pixels by colour. ⇧-click adds, ⌥-click subtracts, then Make transparent.

Pixelate is for visual de-emphasis and not for secure redaction. Cover private information with an opaque filled shape before you export a flattened image.

Files and export

ItsPaint documents use the .itspaint package format, which is a lossless PNG with JSON metadata for the canvas, colours and palette.

Export supports PNG, JPEG, TIFF, BMP, GIF, HEIC, AVIF, PDF and ICO, when the corresponding encoder ships with the installed macOS version. The export panel has format and scale controls, and formats without alpha are flattened onto the second colour.

ItsPaint registers as an editor for PNG, JPEG, TIFF, BMP, GIF and HEIC, so it appears under right-click ▸ Open With.

WebP export is not available, because macOS does not provide a WebP encoder. Text becomes pixels once it is committed.

How it is built

Packages/PaintKit/   UI-free drawing engine, raster operations, undo, and codecs
App/                 AppKit document lifecycle, canvas, and SwiftUI interface

PaintKit stores pixels as premultiplied RGBA8 and returns the changed rectangle from every edit. The canvas redraws only that area, and undo history is bounded by memory rather than by a fixed number of steps.

Background removal without a model is a worked example of both layers. Four corner-seeded flood selections unioned through the same combiner ⇧-click uses, and a guard that declines rather than returning a nearly blank canvas.

That guard was also wrong for three releases, in a way worth reading about: a guard tuned to its test →

PaintKit is a product of the root package, so it can be a dependency of anything that wants a raster canvas without an editor around it. The four-line example is in Contributing above.

docs/README.md has the design notes, architecture, feature reference, testing guide and roadmap. CHANGELOG.md has the version history.

First launch, and the Gatekeeper message

Open System Settings ▸ Privacy & Security and click Open Anyway.

This happened once, on macOS 26.6, with a freshly downloaded 0.12.0, on a disk image that spctl --assess accepts and whose stapled ticket validates. It looks like a first-launch check that went to Apple and did not come back. It is alarming enough when it happens that it belongs here rather than in an issue.

Check the download yourself:

shasum -a 256 -c checksums.txt
codesign --verify --deep --strict --verbose=2 /Volumes/ItsPaint*/ItsPaint.app
spctl -a -vvv -t exec /Volumes/ItsPaint*/ItsPaint.app   # expect: accepted

If you installed it, a star is how the next person finds it from search.

MIT License · Built by Josh Lin