What it does

PDF Merger combines two or more PDF files into a single document, in your browser. Drag files in, reorder them with the handle on each tile, rotate or crop pages with the visual picker, and pick per-file page ranges if you only want a slice. The output preview shows every page in the order it'll be merged so there's no surprise after download.

How it works

• pdf-lib stitches the chosen pages together; it preserves the underlying content as-is so there's no rasterisation and no quality loss.
• pdfjs-dist renders the thumbnails for the visual preview + the per-page rotate / crop controls.
• Crop boxes are applied as PDF MediaBox + CropBox edits, not a re-encode — the output PDF is still a real PDF, not an image-baked one.
• Merge order matches the tile order; the drag-handle reorder updates the preview live.

Limits

• Encrypted / password-protected PDFs aren't supported — we'd need to prompt for the password and re-derive the encryption keys.
• OCR over image-based PDFs isn't supported. Pages stay as they are.
• Signed PDFs lose their signature once re-saved (any merge invalidates the signature).
• Performance is comfortable up to ~200 pages; larger documents work but take a beat to render thumbnails.

Privacy

Every step happens locally — your files are never uploaded to any server. The merge runs in a Web Worker against the bytes already in memory, and the output is generated as a download blob. Close the tab and the files are gone.