Merge, split and compress PDFs privately in your browser

PDF is the format of record for contracts, invoices, bank statements, certificates and scanned IDs, which is exactly why handling PDFs carelessly is risky. Many online PDF services upload your file to their servers to process it. For a bank statement or a signed agreement, that is an unnecessary exposure. This tutorial walks through the most common PDF jobs using tools that run entirely in your browser, so the document never leaves your computer or phone.

How browser-based PDF processing works

Modern browsers can run full PDF engines. Toolew uses two open-source libraries: pdf-lib, which reads and writes the internal structure of a PDF (pages, metadata, annotations), and pdf.js, the renderer that also powers the PDF viewer in Firefox, which turns pages into images for previews and conversions. Because both run locally, processing a 50-page file takes seconds and works even on a slow connection once the page has loaded.

Merging several PDFs into one

Typical uses: combining a cover letter, CV and certificates into one application file, or collecting monthly statements for a loan application.

1. Open Merge PDF and drop all the files at once.
2. Arrange them in order by dragging the rows, or use Sort by name if your files are numbered.
3. To include only some pages from a file, type a range in its page box, for example 1-3, 7.
4. Click Merge PDFs and download the result.

Merging copies pages exactly; text stays selectable and searchable, links keep working and quality does not change. If you plan to print double-sided, the option to insert a blank page after documents with an odd number of pages makes each document start on a fresh sheet.

Splitting a PDF or extracting pages

Splitting is useful when you only need to share part of a document, such as one page of a contract or a single chapter of a report.

• Split PDF can split every page into its own file, split every n pages, or split by custom ranges.
• If you just need a few pages as a new file, extracting them is faster: list the pages you want and download a single PDF.
• To change the order, open Reorder PDF Pages, drag the page thumbnails and save.

When several files are produced, download them individually or as one ZIP archive.

Reducing PDF file size

Email services commonly cap attachments around 20–25 MB, and many government and university portals accept only 1–5 MB. How much a PDF can shrink depends on what is inside it:

• Scanned documents and photo-heavy PDFs contain large images and compress dramatically, often by 70–90%.
• Text-based PDFs exported from Word or a browser are usually small already; there is little to gain.

Compress PDF offers two approaches. The lossless optimisation mode rewrites the file structure more efficiently without changing any content. The image re-rendering mode redraws each page as a JPEG at a resolution and quality you choose, which is the most effective option for scans. Be aware that this second mode turns text into an image, so it can no longer be selected or searched. For scanned paperwork that is usually fine; for a text document, try lossless mode first.

Good settings for scans: 150 DPI and quality 70 for on-screen reading, or 200 DPI and quality 80 if the document may be printed.

Turning photos into a PDF

Phone photos of receipts or handwritten pages are often required as a single PDF. With JPG to PDF you can add several images, order them, choose a page size such as A4 and margins, and create one file. Shrink very large photos first; a 12-megapixel image produces an unnecessarily large PDF page.

Signing a document

Sign PDF lets you draw, type or upload a signature image and place it on any page. This creates a visual signature, the electronic equivalent of signing a printed copy and scanning it. It is accepted for many everyday purposes such as rental forms or internal approvals. It is different from a cryptographic digital signature (for example an Aadhaar eSign or a certificate-based signature), which some legal and government processes require. If you are unsure which a document needs, ask the organisation requesting it.

Common problems and fixes

“This PDF is password-protected.” Files encrypted with an open password cannot be processed until the password is removed. If you know the password, open the file in a PDF viewer and save or print an unprotected copy first.

Fonts look wrong after merging. This is rare, but it can happen with very old PDFs that do not embed their fonts. Re-exporting the original document usually fixes it.

The compressed file is barely smaller. The PDF is probably text-based. Lossless optimisation is the best you can do without reducing quality.

Pages are sideways. Scans are often rotated. Fix them with Rotate PDF before merging so every page reads correctly.

A privacy checklist for PDFs

• Process sensitive documents locally rather than uploading them.
• Remove pages you do not need to share before sending a file.
• Check document properties: PDFs can contain the author’s name, the software used and creation dates in their metadata. The PDF Metadata Editor can view and clear these fields.
• Remember that black rectangles drawn over text in some editors only cover it; the text underneath may still be selectable. True redaction requires removing the content, or re-rendering the page as an image.

With these workflows, most PDF tasks take under a minute and your documents stay entirely under your control.