Unir PDF online

What Unir PDF does

Unir PDF combines two or more PDF files into one document. People use it to send one attachment instead of several, to put a cover letter in front of a CV and certificates, or to collect monthly statements into a single file.

pdf-lib creates a new, empty PDF and copies every page of each file into it, in the order of the file list. Pages are copied as they are, without re-rendering, so text stays selectable. The result is saved as merged.pdf. Bookmarks and document-level settings of the source files are not carried over.

Cómo usar Unir PDF

1. Arrastra tus archivos PDF al recuadro.
2. Ajusta las opciones de la herramienta Unir PDF.
3. Haz clic en Aplicar. El PDF se procesa en tu dispositivo.
4. Descarga el nuevo PDF.

When to use Unir PDF

• Combine a cover letter, CV and copies of certificates into one PDF for a job portal that accepts only a single file.
• Merge twelve monthly bank statements or invoices into one file for a tax return, loan application or accountant.
• Join chapters exported as separate PDFs into one document before sending a thesis or book manuscript to a print shop.
• Put scanned pages that were saved as separate PDF files back together into one complete contract.

Settings explained

Add more files

Drop or choose more PDFs after the first ones; new files are added to the end of the list. You need at least two files, and with only one the tool asks you to add another.

Move up

The up and down arrows next to each file change its position. The list order is the page order: all pages of the first file come first, then all pages of the second file, and so on.

Remove

The cross next to a file takes it out of the list without affecting the other files. Use it to drop a wrong version or a duplicate before you merge.

¿Qué es PDF?

PDF (Portable Document Format) es un formato de documento creado por Adobe en 1993. Los archivos usan la extensión .pdf.

PDF was created by Adobe to show documents the same way on any device and printer. A PDF file describes pages with text, fonts, vector graphics and images at fixed positions. It became an open ISO standard in 2008, and there are special variants such as PDF/A for archiving and PDF/X for printing.

PDF is the right choice for documents that must look the same everywhere, such as contracts, invoices, forms, manuals, reports and files for printing. It also supports digital signatures, fillable forms, comments and password protection.

PDF is hard to edit, because text is stored as positioned pieces, not as flowing paragraphs. Converting a PDF to Word may change the layout. Scanned PDFs contain pictures of text, not real text, unless OCR has been applied.

All major web browsers open PDF files directly. Windows, macOS, iOS and most Android phones include a PDF viewer, and Adobe Acrobat Reader and many free apps can view, annotate and fill PDF forms on all platforms.

Por qué usar Unir PDF de FansBond

La mayoría de los convertidores online suben tus archivos a sus servidores. La herramienta Unir PDF de FansBond hace el trabajo dentro de tu navegador, con WebAssembly y las API modernas del navegador. Tus archivos se quedan en tu dispositivo, lo que es más seguro para fotos privadas, contratos y trabajos sin publicar, y a menudo es más rápido porque no hay que subir ni descargar nada.

Sin colas, sin marcas de agua y sin cuenta. Una vez cargada la página, la herramienta sigue funcionando incluso con una conexión lenta.

Tips for the best result

• To change the order of single pages, or to mix pages from different files, use Organize PDF instead. It shows every page as a thumbnail and can also combine files.
• Files with a password or editing restrictions cannot be merged. Unlock them first with Unlock PDF, then add the unlocked copies.
• Merged pages keep their own size and orientation. If your files mix A4 and Letter pages, use Resize PDF on the result to give every page the same size.
• The result is always called merged.pdf. Rename it before you send it, so the recipient can see what the file contains.

How Unir PDF works in your browser

The PDF is opened with pdf-lib, an open-source PDF library that runs in your browser. Pages are copied, rotated, resized or cropped at the PDF object level, so text stays text and vector graphics stay sharp.

Because the original page content is copied rather than re-rendered, there is no quality loss. The only exception is an option that explicitly turns pages into images. The new PDF is assembled in memory on your device and offered as a download.

Privacy and security

Most online converters upload your files to a server, process them there and keep a copy for some time. Unir PDF works differently: the code is downloaded to your browser once, and your files are read and written only on your device.

You can check this yourself: after the page has loaded, turn off your internet connection and the tool still works. This makes it safe for contracts, IDs, medical records, private photos and unreleased work.