These are the defaults. Every one can be changed in Preferences ▸ Keyboard shortcuts, and the command palette (Ctrl Shift P) always shows the chord that is actually bound.

File

Action Shortcut
New Ctrl N
Open Ctrl O
Save Ctrl S
Save As Ctrl Shift S
Export Ctrl Alt Shift W
Close Ctrl W
Quit Ctrl Q

Export is not Ctrl Shift E. That chord is Merge Visible, here as in Photoshop, and someone pressing it expecting a merge should not get a file dialog. Export takes Photoshop’s Export As chord instead.

Edit

Action Shortcut
Undo Ctrl Z
Redo Ctrl Shift Z
Copy Ctrl C
Paste as New Layer Ctrl V
Command Palette Ctrl Shift P
Preferences Ctrl ,

Copy Selection Mask, Copy Layer Mask, Paste as Selection and Paste as Layer Mask have no default chord; they are in the Edit menu and the palette.

Select

Action Shortcut
Select All Ctrl A
Deselect Ctrl D
Invert Selection Ctrl Shift I

The five Select ▸ Modify entries — Feather, Expand, Contract, Smooth and Border — have no default chord because each opens a prompt.

Image

Action Shortcut
Image Size Ctrl Alt I
Canvas Size Ctrl Alt C

Layer

Action Shortcut
New Layer Ctrl Shift N
Duplicate Layer Ctrl J
Merge Down Ctrl E
Merge Visible Ctrl Shift E

View

Action Shortcut
Zoom In Ctrl =
Zoom Out Ctrl -
Actual Pixels (100%) Ctrl 1
Fit on Screen Ctrl 0

Zoom steps walk a fixed ladder rather than multiplying, so zooming in and out again lands back where you started, and the ladder passes through 100% exactly. The mouse wheel zooms too, anchored on the pointer rather than on the centre of the view.

Tools

Tool Shortcut
Move V
Rectangular Marquee M
Elliptical Marquee Shift M
Lasso L
Polygonal Lasso Shift L
Magic Wand W
Color Range Shift W
Crop C
Free Transform Ctrl T
Eyedropper I
Brush B
Clone Stamp S
Eraser E
Gradient Shift G
Paint Bucket G
Blur R
Sharpen Shift R
Smudge Ctrl Shift R
Dodge O
Burn Shift O
Sponge Ctrl Shift O
Path Edit A
Text T
Shape U
Hand H
Zoom Z

Modifiers on the canvas

Held Effect
Space Pans, from any tool.
Alt with the Zoom tool Zooms out.
Middle mouse button Pans.
Mouse wheel Zooms, anchored on the pointer.

Rebinding

Preferences lists every action with its current chord. Assigning a chord that is already taken tells you which action currently owns it rather than silently stealing it.

+ is a valid key on its own: Ctrl++ binds Ctrl plus the plus key rather than collapsing to a bare modifier.