Quick start
- Start with
https://grandprint.app/app. - Add a question mark, then join settings as
name=value&name=value. - Open the link, choose an image or single-page PDF locally, review the layout, and generate the output.
https://grandprint.app/app?rows=2&columns=3&paper=letter&mode=pdf&unit=inWhy the links are safe
- Only the parameters documented below are read; unknown or malformed values are ignored.
- Values are parsed as bounded numbers or fixed options, never as HTML or executable code.
- The URL never carries image or PDF bytes, a local file path, a file URL, or generated output.
- Opening a link does not upload, generate, print, or download anything automatically.
Parameter reference
Use only the settings your link needs.
URL settings override the same saved editor preferences on that device. Omitted settings use the user's saved preference or the editor default, so agents should include every setting that must be reproducible.
Paper and poster sizing
| Feature | Parameter | Accepted values | Behaviour |
|---|---|---|---|
| Paper preset | paper | square, a5–a1, b4, letter, legal, tabloid, super-b, custom | square switches to the direct 1:1 JPG workflow. |
| Custom paper | paperWidthMmpaperHeightMm | 20–2000 for both | Both are required and are always millimetres, even when unit=in. |
| Displayed unit | unit | mm or in | Changes how measurements are shown; stored physical values remain millimetres. |
| Orientation | orientation | portrait or landscape | Applies to tiled paper. Square mode stays square. |
| Exact grid | rowscolumns | Integers 1–30 | Supply both for an exact grid. Supplying only one requests that many sheets high or wide. |
| Ratio-based target | sizetarget | wide, high, width, or height;
target 0.1–10000 | wide/high target sheet count. width/height target assembled millimetres. |
| Square pixels | squarePixels | Integer 320–8192 | Used only by paper=square. |
Margins, overlap, and image placement
| Feature | Parameter | Accepted values | Behaviour |
|---|---|---|---|
| Margin | marginMm | 0–100 | Unprinted margin on every paper edge, in millimetres. |
| Overlap | overlapoverlapMm | 0/1; 0–100 mm | Set overlap=1 to enable the requested assembly overlap. |
| Anchor | anchor | center, top-left, top-right, bottom-left, bottom-right | Chooses the starting position of the image on the paper grid. |
| Offset | offsetXmmoffsetYmm | −2000 to 2000 | Moves the image from its anchor in millimetres. |
| Zoom | zoom | 0.9–4 | Rounded to the editor's 0.05× steps. |
Assembly helpers and excluded sheets
| Feature | Parameter | Accepted values | Behaviour |
|---|---|---|---|
| Crop marks | cropMarks | 0/1, false/true, or off/on | Adds trim guides to tiled output. |
| Coordinate labels | labels | Same Boolean values | Labels sheets by row and column for assembly. |
| Excluded sheets | exclude | Comma-separated coordinates such as R1C2,R3C4 | Coordinates are one-based and limited to rows and columns 1–30. Square mode ignores exclusions. |
Colour, quality, and output
| Feature | Parameter | Accepted values | Behaviour |
|---|---|---|---|
| Colour mode | colour | colour, grayscale, or monochrome | Sets the export colour treatment. |
| Brightness | brightness | Integer 50–150 | 100 is unchanged. |
| Contrast | contrast | Integer 50–150 | 100 is unchanged. |
| Saturation | saturation | Integer 0–200 | 100 is unchanged; 0 removes colour. |
| Image quality | quality | Integer 20–100 | Applies to raster pages inside PDF, JPG ZIP, and square JPG output. |
| Output mode | mode | pdf, jpg, or jpg-zip | jpg and jpg-zip select a JPG ZIP for tiled paper. Square mode
always produces one JPG. |
Working examples
Open, inspect, and adapt these links.
Letter paper, exact 3 × 2 grid, PDF
A compact North American poster setup with inches shown in the editor.
/app?rows=2&columns=3&paper=letter&mode=pdf&unit=in Open configured editor A4, three sheets wide, with assembly helpers
Uses the source image ratio, a 5 mm margin, 6 mm overlap, trim marks, and labels.
/app?paper=a4&unit=mm&orientation=portrait&size=wide&target=3&marginMm=5&overlap=1&overlapMm=6&cropMarks=1&labels=1&mode=pdf Open configured editor 900 mm-wide grayscale wall print
Targets a physical assembled width and tunes the export appearance.
/app?paper=a4&unit=mm&orientation=landscape&size=width&target=900&colour=grayscale&brightness=100&contrast=110&saturation=0&quality=95&mode=jpg Open configured editor Custom paper and positioned image
Defines paper in millimetres, anchors the image, offsets it, and zooms in slightly.
/app?paper=custom&paperWidthMm=240&paperHeightMm=320&unit=mm&orientation=portrait&rows=3&columns=2&anchor=bottom-right&offsetXmm=-8&offsetYmm=5&zoom=1.15&mode=pdf Open configured editor 2048 px square JPG
Opens the centered, one-image square workflow for a direct JPG export.
/app?paper=square&squarePixels=2048&colour=colour&quality=94&mode=jpg Open configured editor Notes for AI assistants and link generators
- Build the query with a URL encoder such as
URLSearchParams; do not concatenate untrusted text. - Use the canonical origin
https://grandprint.appand the/apppath. - Never claim that a link includes the artwork. Tell the person to choose their image, or a single-page PDF, on their device; a multi-page PDF is tiled from its first page only.
- Ask the person to review paper size, margins, page count, and print scaling before generating output.