This page lists every public tool on stupidPDF. It is a reference for crawlers and answer engines: the tool name, the path, what a person does on the page, and how the tool works. People can read it too.
stupidPDF is a free browser toolkit at https://www.stupidpdf.com/. There is no account. Files are processed in the browser and are not uploaded to a stupidPDF server. Two tools are different and say so below: AI sends extracted text to Google Gemini with a key you provide, and Share moves a file directly to another browser. OCR may download language data before it reads a scan on the device. A password-protected PDF asks for that password on the device before a tool reads it.
Build one PDF from several PDFs and images. Page order is visual: a page from one file can sit between pages of another.
How to use
Open /merge.
Drop two or more PDFs or PNG/JPEG images.
Drag pages in the filmstrip to set the final order. File cards add, remove, or restack a whole file.
Press Merge PDFs, or Merge when the drop includes images.
Download the PDF. The page count is shown when it is ready.
How it works
Each file is read in the browser. The worker copies the chosen pages into a new PDF in the order on screen. Images become pages. Nothing is uploaded to stupidPDF.
Convert Markdown, code, and Mermaid diagrams to PDF
Turn Markdown into a formatted PDF. You can drop .md, .markdown, or .mdown files, type Markdown in the box, or both. Mermaid diagrams in the Markdown are drawn and embedded.
How to use
Open /markdown.
Drop Markdown files, or type Markdown in the box. A typed note is enough; files are optional then.
Press Convert to PDF.
Download the PDF. A single dropped file with no typed text uses that file name with a .pdf extension. Otherwise the download is markdown.pdf.
How it works
Mermaid blocks are rendered to PNG in the browser. The worker then turns the Markdown and those images into PDF pages. The source is not uploaded.
Extract selected pages, every page, half, or by size
Pull pages out of one PDF, or cut it into several files in a ZIP.
How to use
Open /split and drop one PDF. Thumbnails appear. Clicking pages fills the page box when the mode is a range.
Choose a mode: Extract page range, Every page (ZIP), Split in half (ZIP), By max size (ZIP), By bookmarks (ZIP), or Where text appears (ZIP).
For a range, type pages such as 1-3,5,7. For size, set a max KB. For text, type the text that starts a new part.
Press Extract pages for a range, or Split into ZIP for the other modes.
Download one PDF or a ZIP of PDFs.
How it works
Range mode copies the listed pages into one PDF. Every-page mode makes one PDF per page. Half mode cuts the document in two. Size mode packs pages until the next page would pass the byte cap. Bookmark mode uses the outline to make ranges. Text mode starts a new part where the extracted page text contains the phrase. All of that runs in the browser. This is not OCR.
Select pages in the filmstrip. If none are selected, every page is rotated.
Choose 90° clockwise, 180°, or 90° counter-clockwise.
Press Rotate and download rotated.pdf.
How it works
The worker rewrites the selected page rotations inside a new PDF. Unselected pages stay as they were when a selection exists. The file stays on the device.
Trim the edges of selected pages, then optionally fit the result to A4, Letter, or a custom page size.
How to use
Open /crop and drop a PDF.
Select pages in the filmstrip.
Set units to points, inches, or millimeters, and enter the top, right, bottom, and left crop.
Optionally choose a target size: none, A4, Letter, or custom width and height.
Press Crop and download cropped.pdf.
How it works
Crop amounts are converted to PDF points (72 points per inch) and applied to the selected pages in the worker. A target size resizes those pages onto that paper. The file stays on the device.
See pages — reorder, remove, duplicate, and rotate
Reorder pages, insert blanks, duplicate, delete, reverse, rotate, or recolor.
How to use
Open /organize and drop a PDF.
Drag thumbnails, or use Move left and Move right. You can also type a 1-based order such as 3,1,2.
Use Duplicate, Delete, Insert blank, Reverse, Rotate left, or Rotate right on the selection. An empty selection acts on the first page for moves that need one page.
Optional recolor: Invert, Sepia, or Grayscale, applied to the selected pages.
Run the page action and download the PDF.
How it works
The filmstrip is the page list. The worker rebuilds the PDF in that order, with blank inserts and rotations. Recolor renders the selected pages to new images and puts those images back into the PDF. All of this is local.
Fill existing form fields, drop new text, or place a signature on the page you are looking at.
How to use
Open /fill and drop a PDF. The page opens on screen.
Click an existing field and type. Or choose Text or Sign, then click the page to place it.
Move or edit the items you added until the page looks right.
Download the filled PDF.
How it works
The PDF is drawn in the browser. Field values and placed text or signature images are written into a new PDF on the device. The form is not submitted to a server.
Stamp text or an image across selected pages. If you select nothing, every page is stamped.
How to use
Open /watermark and drop a PDF.
Select pages, or leave them unselected for all pages.
Choose Text or Image. For text, set the words, font size, opacity, and rotation. For an image, choose the image file.
Press the stamp action and download the PDF.
How it works
The worker draws the text or image onto each chosen page and saves a new PDF. Opacity and rotation are applied in that draw. The stamp asset stays on the device.
Write six header and footer slots. Tokens {page}, {total}, and {date} are replaced per page.
How to use
Open /headers and drop a PDF.
Fill any of header left, center, right and footer left, center, right. Empty slots are skipped.
Use {page}, {total}, or {date} inside any slot.
Run the tool and download the PDF.
How it works
The worker paints the six slots into the page margins. {page} is the page number, {total} is the page count, and {date} is the date at run time. Processing is local.
Bake fillable fields and annotation text into the page, and strip page actions and open actions. Pages are not deleted.
How to use
Open /flatten and drop a PDF.
Press the flatten action.
Download flattened.pdf.
How it works
The worker flattens the AcroForm when one exists, draws annotation text onto the page, then deletes the annotation array and page additional-actions. It also removes the catalog open action, additional-actions, and the name tree. The new PDF is built in the browser.
Read hidden info fields, strip them, or write title, author, subject, and keywords.
How to use
Open /metadata and drop a PDF.
Read the fields the tool shows.
Edit title, author, subject, or keywords, or strip the hidden fields.
Download the rewritten PDF.
How it works
The worker reads the PDF info dictionary on the device, then saves a copy with your edits or with those fields removed. The document body is not uploaded.
Pull the text layer from each page and show it. This is not OCR. A scanned page with no text layer stays empty here; use /ocr for that.
How to use
Open /extract-text and drop a PDF.
Read the per-page text.
Use the copy control if you want the text on the clipboard.
How it works
The worker reads PDF content streams and returns best-effort text per page. It does not send the PDF out and it does not recognize pictures of letters.
Put two PDFs side by side. The page reports page count and file size, and the two views scroll together.
How to use
Open /compare.
Drop the two PDFs.
Read the count and size comparison and scroll either preview.
How it works
Both files stay in the browser. The page compares metadata you can see (page count and byte size) and renders both documents locally. It does not produce a merged file and it does not upload either PDF.
Shrink one PDF. Presets are High quality, Balanced, and Small file. An optional max size in KB tries presets until one fits, or reports that the file is still over the cap.
How to use
Open /compress and drop a PDF.
Pick a preset, or type a max size in KB. A max size disables the preset menu because the cap chooses the preset.
Optional: press Compare presets to see a bench of sizes without committing to one download.
Press Compress. The status line shows bytes before, bytes after, and the percent reduction.
Download compressed.pdf.
How it works
The worker recompresses the PDF in the browser. With a byte cap it picks the smallest preset that lands under the cap when one does. The file is not uploaded. Compare presets only prints sizes; it does not replace the download until you press Compress.
Run several tools in order on one PDF. Steps can be reordered. Available steps: Compress, Watermark, Page numbers, Rotate, Bates, Crop, Flatten, Encrypt, Headers, and Strip metadata.
How to use
Open /workflow and drop one PDF.
Set step 1, then add steps. Move a step up or down, or remove it.
Fill the options for that step: compress preset, watermark text, rotate degrees (90, 180, or 270), Bates prefix and start number, crop inset in points on every edge, encrypt password, or header center text. Page numbers, flatten, and strip metadata need no extra field.
Press Run workflow and download workflow.pdf.
How it works
The worker applies each step to the bytes from the previous step, in list order, inside the browser. Encrypt uses only the password typed into that step. Strip metadata removes info fields. The PDF is not uploaded.