AiReader

Version 1.5 · by Aizu, Aisoft Technology (aisoftdigital.com). A fast, light PDF reader. No ads, no account, no sign-in. Opens a PDF in about a tenth of a second.

Install (one time)

1. Close any open AiReader window.
2. Double-click install.bat in this folder.
3. A Windows Default apps window opens. Set .pdf to AiReader.
4. Done. Double-click any PDF to open it. AiReader is also in the Start menu.

Portable version (USB drive)

• Copy AiReader-x.y.z-portable.exe to a USB drive (or any folder) and double-click it. Nothing to install.
• It keeps its settings, remembered pages and search cache in an AiReader-data folder next to itself, so they travel with the drive. Nothing is left on the PC.
• It does not make itself the PC's PDF reader. To do that, use the installer.

The screen

• Left: your open PDFs, one tab each. Click a tab to switch, drag it up or down to change the order, click its × (or middle-click) to close, Open PDF to add one. If you switch it on in Settings (off by default), Recent lists your last 10 PDFs: click one to open it, click its × (or middle-click) to take it off the list. Dragging PDFs onto the window opens them too.
• Right: the toolbar. From the top: search, open, the page number box (click it, type a page number, press Enter), previous / next page, rotate, 1:1 actual size, fit width, zoom in, zoom out, zoom %, dark mode, show / hide tabs, the pen (edit tools). At the bottom, the menu (≡) with About AiReader.
• Middle: the document, using the full height of the window, always centred; if a page is wider than the window you start in its middle.
• Opening a PDF while AiReader is already open adds a tab to the same window.
• Each PDF reopens on the page and zoom where you left it. Dark mode and your zoom choice carry over to every PDF you open.

Search

• Press Ctrl+F (or /, or the magnifier at the top right) and type. Results appear as you type.
• Every match is highlighted in yellow; the current one in orange. The list shows each match with its page and the words around it. Click one to jump to it.
• Enter / F3 next match, Shift+Enter / Shift+F3 previous, Esc closes search.
• Upper and lower case are treated the same. A word split over two lines with a hyphen is still found.
• With the box empty, your last 10 searches are listed: click one, or use ↓/↑ and Enter.
• The search box can be moved: drag it by the bar at its top (or any empty part of its header). It stays where you put it; double-click the bar to send it back to the top right.
• Scanned PDFs (pictures of paper) have no text, so search cannot find anything in them. AiReader tells you when that is the case.

Copy text

• Drag over text to select it, or double-click a word. Ctrl+A selects the whole page.
• Ctrl+C copies. Dragging where there is no text moves the page instead.

Mark up and edit

• Highlight, underline or strike out text: select it (drag over it, or double-click a word). A small bar appears above it: highlight, underline, strike out, copy. Right-clicking the selection offers the same.
• More tools: click the pen at the bottom of the toolbar (or Ctrl+E). A second column opens next to the toolbar. From the top: select, highlighter (drag over text), pen, text box, note, rectangle, ellipse, arrow; then colour and size, page tools; undo, redo; save. A tool stays on until you pick another one or press Esc.
• Text box: click where it goes and type. Note: click where it goes and type; it shows as a small icon, and its text appears when you point at it. Click elsewhere, Esc or Ctrl+Enter finishes. Double-click a text box or a note to change its text.
• Change a mark-up: click it (a blue frame shows it is selected). Drag it to move it (with the edit tools open), Delete removes it, the colour button (or right-click, Colour) recolours it. This works for mark-up made in other programs too.
• Pages: right-click a page (or use the page button in the edit tools): rotate it, move it up or down, insert a blank page after it, insert all pages of another PDF after it, or delete it.
• Undo / redo: Ctrl+Z / Ctrl+Y, for mark-up and page changes alike. After saving, undo starts over.
• Save: Ctrl+S (or the save button). A dot on the tab and a * in the title mean unsaved changes; closing the tab or AiReader asks whether to save them. Ctrl+Shift+S saves under a new name, and the tab then shows that file.
• Mark-up alone is saved by adding the changes to the end of the file (quick, and digital signatures stay valid). After deleting pages the whole file is written again, so the deleted pages are really gone from it. Password-protected PDFs stay protected.

Settings

Menu (≡, bottom right) → Settings, or Ctrl+,. Changes apply and save immediately.

• View: zoom for newly opened PDFs (last used, fit width, actual size, or a fixed %), dark mode, tabs, remember the page and zoom of each PDF, show recent PDFs on the left.
• Search: match case, whole words only, the size of the search cache with a Clear button, how long to keep cached text.
• Keyboard: vim keys on / off, scroll speed.
• Files: make AiReader your PDF reader (installed version only); clear the recent PDFs and searches.

All keys

Speed (measured on this laptop, 28 Sep 2026)