Single shows one page at a time, centered.

Continuous scrolls every page in one vertical strip.

Two-Page shows facing pages as spreads. Press B to toggle book layout, which leaves the cover page by itself before pairing the remaining pages.

Grid lays out every page as a thumbnail wall for a whole-document overview.

Switch from the toolbar or with F5 to F8. Every mode shares the same annotations and zoom, so nothing shifts when you change layout.

The current page appears in a small corner badge while you navigate, then slides away when the view settles.

Touch: drag with one finger to pan the document, or pinch around the point you want to keep in view. Touch navigation works in every page layout.

Open as many PDFs as you like, each in its own tab.

Ctrl+Tab and Ctrl+Shift+Tab cycle through them.

Ctrl+W closes the current tab; Ctrl+Q closes them all.

Each tab remembers its own zoom, view mode, page, scroll position and tool, so switching back drops you exactly where you left off.

The active tab always stays visible; when the strip fills up the rest move into an overflow menu.

Press F10 to show two documents side by side in one window - each pane is its own card, and the focused one carries an accent ring so it is obvious which pane the toolbar, sidebar and page list are acting on.

Click either pane to move focus, or drag its resize handle to size it; neither pane can be squeezed below a readable width.

Drag a tab from one pane's strip onto the other to move it across. View state and document-color inversion are tracked per pane, so changing one side does not disturb the other. F10 again closes the split.

A maximized or snapped window splits its space evenly instead of squeezing the second pane down to its minimum.

Choose Compare PDFs from the toolbar, then select the second document. KillerPDF opens both files side by side and pairs their pages.

Page navigation, zoom and scrolling stay synchronized. Difference regions are marked directly over the pages, with a changed percentage for each pair.

The results also identify different page dimensions and pages that exist in only one document. You can export the comparison report without changing either source PDF.

A dockable sidebar with two tabs: Pages (live thumbnails) and Outline (the PDF's bookmarks). Toggle the whole thing with F9.

Reorder pages by dragging a thumbnail; a drop indicator shows where it will land.

Multi-select: select several thumbnails and drag any selected page. The whole selection moves as one ordered block.

Drop PDFs or images on the insertion line to place them at that exact page position. In Split Pane, selected pages can also be dragged directly into the document on the other side.

Multi-select pages, then rotate, extract or delete them all at once.

Right-click a thumbnail for the full page menu: Insert blank page, Duplicate, Rotate clockwise / counter-clockwise, Move up / down, Extract pages to a new PDF, Delete pages, or Stamp pages.

Drag the slim splitter to resize the sidebar, and dock it on the left or right from the sidebar's right-click menu, or press Shift+F9 - it remembers your choice. A toggle strip collapses it to a thin rail.

The Outline tab shows the PDF's bookmark tree; click any entry to jump to its page. Top-level bookmarks start visible while deeper levels begin folded, and your expand/collapse choices survive tab switches and bookmark edits. It sizes itself to the widest bookmark the first time you open it.

Ctrl+F opens a small floating search bar you can drag anywhere.

It searches the whole document as you type (after two characters), case-insensitively, and can match phrases that run across adjacent words.

Enter jumps to the next match, Shift+Enter to the previous, wrapping around the document; the status reads current / total.

Every match stays highlighted while you scroll - the current one brighter and thicker, the rest dimmer - and the highlights survive zooming and re-rendering.

Zoom runs from 5% to 500% in 15% steps; Ctrl+0 snaps back to 100%.

Ctrl + mouse wheel zooms around the point under your cursor, so the spot you are reading stays put.

The zoom box also offers Fit Width and Fit Page, computed exactly to the page size.

In Grid view the wheel changes the number of columns instead, so you zoom by fitting more or fewer pages across the window.

Clickable links already in the PDF light up with a hand cursor.

Left-click follows them - an internal link jumps to its page, an external one opens in your browser.

Right-click a link to copy its URL or remove it.

Press T (or toolbar slot 1), click anywhere, and start typing a note. Enter saves it, Escape cancels.

While it is selected, the floating text bar sets the font, point size, color, an optional background fill, and Bold / Italic / Strikethrough / Underline.

Use Spacing to adjust the distance between characters. The live editor, line wrapping and saved PDF all use the same spacing, which is useful for lining text up with preprinted form boxes.

Drag the box's corner handles to set its width - the text wraps to fit.

Double-click a note any time to re-edit the wording.

This is the part most editors fake. Double-click a line of real PDF text with the Select tool, and KillerPDF reads the actual words underneath and drops two linked annotations:

1. A Cover - an opaque box that blocks out the original words. It does not just slap down white: it samples the page just above and below the line and matches that background color, so a cover over a colored header blends in.

2. A Text box on top, pre-filled with the detected words and starting in the same color and size - the font and point size are read straight from the original letters.

The two are locked together as a pair. Selecting either half dash-outlines its partner, so you never lose track of the other piece.

Make sure the old words are really gone. Click the cover (the background area) and use its settings bar to change its color, or drag its corner handles so it fully covers the original. A cover is always 100% opaque on purpose - it can never go see-through and let the old text ghost back.

Then resize and restyle the new text like any text box: drag the handles for width, change the font, size, color or weight.

Right-click either piece to Select Cover / Select Text - this jumps the selection to the other half - or to Unpair them into two independent annotations.

The whole edit counts as a single undo, and on save it flattens to a clean filled box with your new text on top.

On a scanned page with no text layer, you get an empty cover and text box at the click point: type your replacement, then drag the cover over the scan to white the old text out by hand.

See how the cover-pair is built, with a diagram, on the Technical page →

Press H and drag to lay a highlight over text. Color and opacity live on the bar; the default is yellow at low opacity.

The Highlight tool has an Eraser toggle, and it works two ways.

Brush: drag over a highlight and it carves a smooth, round-edged gap out of it - one anti-aliased shape, not a blocky strip or seam. A circular brush footprint shows where the next pass will land.

Box: drag a rectangle (shown as red marching-ants) and it deletes whole annotations inside the box.

The brush only carves fill highlights and splits ink strokes; text, images and signatures are left untouched.

Press D for freehand Draw - round-capped ink that keeps drawing stroke after stroke without re-arming.

Draw has its own Eraser toggle: a brush (with a translucent gray footprint preview) that passes over your ink and splits the strokes wherever it touches, rubbing out just those parts rather than deleting whole strokes.

Press L (or U) for the Line tool, a straight two-point segment.

Turn on Level and the line snaps to perfectly horizontal or vertical, whichever your drag is closer to.

All three carry color, opacity and width on their bar.

The Shapes tool draws rectangles, ellipses and free-form polygons, each with an optional fill - pick the sub-mode and toggle Fill on the bar.

Box keeps the classic drag-a-rectangle gesture. Ellipse drags the same way as a closed outline.

Freeform places points click by click: click the first point again (its target lights up when you are close) or double-click to close the polygon, Esc cancels, Backspace removes the last point.

Shapes share the draw bar's color, size and opacity, and move, resize, flatten and print like any other drawing.

Press I, click the page, and pick an image file.

It lands at half size; drag a corner handle to resize it.

You can also right-click the page and choose Image to drop one exactly where you clicked.

With the Select tool, drag an empty area to rubber-band select everything the box touches. Because the box floats above the pages, one drag can grab annotations across several pages in Continuous or Grid view.

Shift-click adds or removes individual annotations from the selection; Ctrl+A selects them all.

Right-click a multi-selection and choose Group to bind them together. After that, clicking any one moves, copies or deletes the whole group as a unit.

Ungroup dissolves the group; Remove from group drops just one member.

Use Raise and Lower on the right-click menu to change which annotation sits on top where they overlap.

A selected annotation gets an accent outline and four corner handles. A text box's handles set its width; images, signatures and highlights resize freely. The outline and handles stay the same on-screen size no matter how far you zoom.

When you drag across real PDF text, selection follows the page's reading columns instead of sweeping across neighboring columns; copied text keeps that column order.

Press C to crop. A box appears inset from the edges with draggable corner handles, plus exact X / Y / W / H fields.

Switch the units between points, inches or %. Pressing Enter in a field both sets and applies the value.

Crop the current page, a typed range like 1-3,5, or tick All for every page.

It writes a real /CropBox and /TrimBox into the PDF and is fully undoable; Remove crop puts it back.

Choose the ruler button from the toolbar, then drag between any two points on a page.

The live readout shows the measured distance in points, inches and millimeters, along with the page dimensions. Calculations use the real PDF page size, so the result stays consistent at every zoom level and page rotation.

Measurement is temporary reference information. It does not add an annotation or alter the PDF.

Press R to open Transform. Quick 90-degree turns are separate actions on the page and thumbnail right-click menus.

Ctrl+R rotates selected pages 90° clockwise. Ctrl+Shift+R rotates them 90° counterclockwise.

The Transform window does more: rotate by any angle, scale, flip horizontally or vertically, and straighten a crooked scan by drawing a level line across it.

Selected-page batches: open Transform with several thumbnails selected to preview each page and apply one undoable operation to the complete selection.

Output quality: choose 72 to 600 DPI, keep full color, convert to grayscale, or use an adjustable black-and-white threshold. Optional JPEG compression provides a quality control for reducing output size.

Levels: adjust black point, white point and gamma against a live histogram to recover faded scans or improve contrast before applying the transform.

Correct trapezoidal distortion: expand Perspective, turn the correction on, then drag the four green corner handles to the corners of the rectangular object in the page. This is useful for photographed documents, signs and screens that appear narrower on one side.

The four sides must form a valid shape and must not cross. Use Reset in the Perspective section to return the handles to the page corners, or Reset all to clear every transform setting.

The preview updates as you move the handles. Choose Apply to rebuild the page at full resolution. The edit is physical, includes the page annotations, refreshes every visible view immediately, and can be reversed with Ctrl+Z.

Insert or append blank pages, delete, duplicate, move up or down, and extract or split pages out to a new PDF. In 1.8.5, you can choose the blank page size.

Most of these live on the thumbnail right-click menu; drag thumbnails to reorder.

Structural edits are undoable, and your annotations follow their pages.

Open images - JPG, PNG, BMP, GIF, TIFF - as PDF pages; multi-page TIFFs and GIFs come in frame by frame.

Drop a folder and it recurses through everything inside; drop a .zip and it extracts first.

When you drop several files at once, KillerPDF asks whether to merge them into one PDF or open each separately (up to 50 at a time).

Press S to open one window with a live preview that steps through your pages, holding two independent jobs.

Page numbers: set a start number and a format using {n} for the current page and {N} for the total - for example Page {n} of {N}.

Choose the font size, color, a page range, and one of eight positions (or drag a custom spot).

Turn on Mirror and the numbers flip to the outer edge on facing pages, like a printed book.

Watermark: stamp text or an image across any page range, with adjustable size, angle (-90 to 90), opacity and position.

Stamps draw beneath your annotations, count as a single undo, and you can double-click one to edit it again.

Interactive form fields - text, multi-line, dropdowns, checkboxes, radio groups and signature fields - become editable right on the page, in every view mode.

While a text field is focused, a small font-size stepper ( - N + ) lets you size the text, and it is saved into the field.

Comb fields cap input at their printed cell count and save one character in each box.

Form-aware OCR: existing field rectangles can become OCR boundaries. KillerPDF honors numeric constraints, maximum lengths and comb cells, then checks recognized text against dropdown and list choices.

Fields show a faint cream fill with an accent border when focused.

On save your entries are written back into the PDF and the fields stay real, editable form fields - they are not destructively flattened.

Sign a document cryptographically with a certificate from a .pfx / .p12 file or the Windows certificate store.

Windows-compatible USB security tokens are supported through the certificate store and can show their normal PIN prompt while signing.

It uses SHA-256 and embeds the whole certificate chain.

Add an optional reason, location and contact, and it writes a signed copy alongside the original.

The visible signature layout is editable before signing. Choose its placement and combine certificate details, signer text and an optional image without changing the cryptographic signature itself.

Press G to open the signature popup. Draw a signature on the pad with three pen widths (thin, medium, thick), or import an image of one.

It keeps two kinds: full Signatures and shorter Initials, saved for reuse so you only draw them once.

Drop a saved signature anywhere on the page, or straight into a form sign-field - it centers and scales to fit, and remembers your pick for that kind of field.

A signed field then offers Change or Remove.

KillerPDF reads text off scans and images with on-device OCR - nothing is ever uploaded.

OCR Page (Ctrl+Shift+O) copies the current page's text to the clipboard and reports a confidence figure.

OCR Region (Ctrl+Shift+I) lets you drag a box to OCR just that area to the clipboard.

Make Searchable PDF adds an invisible real-text layer aligned over the words, so search and text-select start working on a scan.

Extract All Text dumps the whole document to a .txt or .md file.

Languages and models: OCR supports sixteen languages: English, Spanish, French, German, Czech, Hungarian, Italian, Japanese, Kazakh, Polish, Russian, Turkish, Bengali, Vietnamese, and Chinese in Simplified and Traditional forms. Models download on demand and remain cached.

Each language offers a Standard model (smaller, faster) or a High Quality model (larger, more accurate), and once downloaded they are cached so you only fetch them once.

Pages are rendered at about 300 DPI for accuracy.

Ctrl+P opens a real print preview. The Printer, Layout and Output sections collapse independently so the controls you need stay in view.

Choose the printer's paper size and paper source, then print 1, 2, 4, 6 or 9 pages per sheet (N-up), with scale (Fit / Actual / Custom %), a 9-way alignment, margins, a page range, color or black-and-white, copies, and two-sided output when your printer supports it.

A subset selector under Pages prints all pages, odd only, or even only - applied on top of the page range, with the preview following along. Print the odds, flip the stack, print the evens: manual duplex for printers without a duplexer.

Live preparation and spool progress show exactly where a large print job is, and cancellation remains available while it is being prepared.

Output is rendered at a true 300 DPI.

If the document has annotations or stamps, they are flattened onto a throwaway copy for printing, so your live document is untouched. You can also save a flattened, uneditable copy.

F4 opens Document Info.

View and edit the PDF's title, author, subject, keywords and creator, all saved back into the file.

Click the footer status line or press Shift+F4 to show the current file size briefly.

KillerPDF sends no telemetry. Document processing, including OCR, runs locally. Checking GitHub for updates and downloading updates or extra OCR models use the internet. In 1.8.5, you can turn startup checks off; installing an update requires confirmation.

On a shared machine, the recent-files list is the one trace of what you opened. Clear list lives on the start screen's Recent panel and in the Open dropdown, and the About window (F12) has a "Don't remember recently opened files" toggle next to Clear all Data - turning it on also empties the existing list.

Clear all Data in the About window wipes every stored setting and saved signature in one go.

KillerPDF.exe is the compact installer. It requires the Microsoft .NET 10 Desktop Runtime and offers per-user or all-users installation. If the runtime is missing, the installer opens Microsoft's official download page.

KillerPDF-Portable.exe contains its own runtime and can run without installation, including on an offline computer.

Per-user installs live under %LOCALAPPDATA%\Programs\KillerPDF. All-users installs live under %ProgramFiles%\KillerPDF. The installer prevents both scopes from remaining installed at the same time.

Thirteen themes - Dark, Light, Black, 98SE, Blood, Greed, Cyanotic, Ectoplasm, Decay, Malaise, Sepulchre, Delirium and Mourning - switch live, and four of them - Dark, Light, Black and 98SE - each take one of six accent colors, so 33 looks in all.

The sidebar docks on the left or right.

The interface is translated into sixteen languages, including Vietnamese, Italian, Kazakh, and Russian. Every interface language has a matching downloadable OCR model.

Invert document colors: the moon toggle at the bottom of the sidebar rail (or the N key) renders the document with inverted colors for dark-mode reading. In split view this setting belongs to the focused pane. It is display only - saving, printing, exporting, OCR and thumbnails keep the document's true colors - and is remembered across launches.

App size: scroll the mouse wheel over the title-bar logo (or Ctrl+Shift and + / -, Ctrl+Shift+0 to reset) to scale the whole interface from 70% to 250% - toolbar, sidebar and tabs, while the document keeps its own zoom. Made for tired eyes and high-DPI laptops alike.

Saving, exporting, flattening, signing, searchable OCR, forms, annotations and structural page edits are powered by The KillerPDF.Engine, an independent .NET 10 PDF library built from scratch.

The Engine preserves complete page and catalog structures, including forms, tags, bookmarks, named destinations, layers, attachments and inherited page settings. It validates output before writing and fails safely when an unsupported structure cannot be preserved.

Open the Engine architecture, API and validation guide →

Every core operation also runs headless from PowerShell or cmd - no window opens, and it works even while KillerPDF itself is running.

Run KillerPDF-Portable.exe directly, or use the installed KillerPDF.exe under %LOCALAPPDATA%\Programs\KillerPDF or %ProgramFiles%\KillerPDF.

Exit codes are the scripting contract: 0 success, 1 the operation failed, 2 bad usage. Check $LASTEXITCODE in PowerShell.

KillerPDF.exe --help prints the full reference; --version prints the version. Because KillerPDF is a windowed app, console text can interleave with your prompt - that is normal.

Page ranges are written like 1-3,5,9-12. Encrypted inputs are unlocked automatically where possible; pass --password <p> for password-protected files.

KillerPDF.exe --merge out.pdf a.pdf b.pdf scan.jpg merges PDFs and images into one file, in the order given.

Merges rewrite named-destination links, so internal cross-references and TOC links keep working in the combined file.

KillerPDF.exe --extract-pages in.pdf 1-3,5 out.pdf pulls a page range into a new PDF.

KillerPDF.exe --split in.pdf pages\ writes one PDF per page, named in-page-001.pdf and so on.

KillerPDF.exe --decrypt locked.pdf open.pdf removes encryption losslessly (bookmarks and forms survive). Add --password <p> if the file needs a password to open.

KillerPDF.exe --flatten in.pdf flat.pdf rasterizes every page into an uneditable PDF, the same 150 DPI output as Save Flattened in the app. --dpi overrides the resolution.

KillerPDF.exe --to-image in.pdf imgs\ --dpi 300 --format jpg renders pages to PNG (default) or JPG files. --pages limits the range.

Rotated pages come out in their viewed orientation in all three.

KillerPDF.exe --print in.pdf --printer "HP LaserJet" --pages 1-4 --copies 2 prints silently at 300 DPI, fit-scaled and centered. Without --printer it uses the Windows default; a partial printer name matches too, and a bad name lists what is available.

KillerPDF.exe --ocr scan.pdf searchable.pdf --lang eng lays an invisible, selectable text layer over a scan - the same on-device OCR as the app, nothing uploaded.

Language models (eng, spa, fra, deu, ces, hun, ita, jpn, kaz, pol, rus, tur, ben, chi_sim, chi_tra) download automatically on first use and remain cached.

KillerPDF.exe --batch-resave inDir\ outDir\ --log report.csv resaves a file or a whole folder tree through the standard open/save pipeline, mirroring the folder structure.

Each file reports OK, SKIP (with a reason), or FAIL, to the console and the optional CSV log.

This powers KillerPDF's standards-conformance testing: resave a validation corpus, run veraPDF over input and output, and diff the results with validation/Compare-VeraPDF.ps1 from the repo. The claim it verifies: a KillerPDF save does not degrade PDF/A conformance.