Combine PDFs into one document or shrink oversized files, entirely in your browser. Your documents never leave your device.
Processed 100% locally in your browser — files never leave your device.
Popular PDF Tools Presets & Scenarios
Job applications are the classic case: a posting asks for 'one PDF' but you have a resume, a cover letter, certificates, and references as separate files. Merging them into a single document in the right order takes seconds and looks far more professional than four attachments. The same applies to expense reports (receipts + form), rental applications (ID + payslips + references), visa paperwork, and school admissions packets.
Contracts and agreements benefit too. When a deal involves a main contract plus appendices, annexes, and signed signature pages collected over email, combining everything into one authoritative file prevents the all-too-common 'which version is final?' confusion. Reorder pages by dragging before you merge, so the finished document reads in a logical sequence.
Bloated PDFs almost always come from two sources: full-resolution camera photos embedded onto pages without prior compression, or accumulated document metadata and incremental cross-reference histories generated by office suites. A ten-page scan can easily exceed 20–50 MB, which bounces off email servers and gets rejected by upload portals capped at 5–10 MB.
Honest scope of our Compress tab: Because YuliusBox runs 100% in your browser via pdf-lib without uploading your paperwork to a server-side Ghostscript cluster, the Compress (Metadata Cleanup) tab strips document Info dictionary fields (Title, Author, Subject, Keywords) and re-serializes the PDF object tree cleanly, without re-encoding embedded raster image streams. If your PDF is oversized because of camera scans or photos, shrink the source JPG/PNG files in our local Image Compressor first (which cuts photo byte weight by 60–80%), then click the built-in handoff button to assemble them in the JPG to PDF tab in one seamless in-memory workflow.
YuliusBox uses pdf-lib 1.17.1 and JSZip 3.10.1 to manipulate PDF cross-reference tables and page trees directly inside your browser tab's memory. Merging calls PDFDocument.create() and copyPages() to graft page dictionaries from each source file into a single unified document; Split loops through src.getPageCount(), writes each page into a standalone PDFDocument, and packages all page-N.pdf files into a single ZIP archive in memory; Extract parses custom page range expressions (such as 1-3, 7, 9-10) into 0-based page indices; and JPG to PDF embeds raw JPEG or PNG byte buffers via embedJpg()/embedPng() onto full-resolution pages matching the exact pixel dimensions of each image.
How to verify zero-upload execution in Browser DevTools: Open DevTools (F12) -> Network tab, clear the request log (or switch Network Throttling to Offline), and run any Merge, Split, Extract, Compress, or JPG-to-PDF operation. You will confirm that zero network requests are dispatched — every byte stays inside your local browser memory and downloads via a blob: URL.
| PDF Toolkit Mode | Test Input Profile | Input Byte Size | Output Byte Size | Execution Time | Underlying Client-Side Operation |
|---|---|---|---|---|---|
| Merge PDF | 5 A4 PDFs (5 pages each = 25 pages) | 29.26 KiB (29,965 B) | 24.97 KiB (25,568 B) | 69.71 ms | PDFDocument.create() + copyPages() deduplicating shared structure |
| Split PDF (to ZIP) | 10-page A4 contract PDF | 10.98 KiB (11,247 B) | 18.02 KiB (18,451 B ZIP of 10 PDFs) | 23.90 ms | 10 × single-page PDFDocument.save() + JSZip.generateAsync() |
| Extract Pages | Range '1-3, 7, 9-10' (6 of 10 pages) | 10.98 KiB (11,247 B) | 6.87 KiB (7,034 B) | 3.40 ms | parsePageRanges() + 0-based copyPages([0,1,2,6,8,9]) |
| JPG to PDF | 3 × 1920x1200 JPEG scans | 1.09 MiB (1,139,139 B) | 1.09 MiB (1,140,758 B, +1,619 B wrapper) | 34.82 ms | Direct embedJpg() stream wrapping without lossy re-compression |
| Compress (Metadata Cleanup) | 10-page A4 PDF with verbose Info tags | 11.82 KiB (12,108 B) | 10.98 KiB (11,243 B, -865 B) | 7.15 ms | Clears Title/Author/Subject/Keywords & re-serializes xref stream |
Order matters more than people think. Put the cover letter or summary first, supporting evidence after, and always double-check the page order in the preview before merging — reviewers notice when a certificate appears before the resume. Keep file names descriptive before you upload them; 'resume-2026.pdf' beats 'document-final-FINAL-2.pdf' when you are dragging a dozen files into order.
For compression, try the default setting first and check the result. If text still looks crisp and images are acceptable, you are done. Only re-run with stronger settings if the file is still over the limit, and keep the original — you cannot un-compress a PDF any more than you can un-compress a photo.
Choose a tab: Merge to combine files, Compress to shrink one, Split to break it apart, Extract to pull out specific pages, or JPG→PDF to create a PDF from images.
Drop your PDF (or image) files in — drag to reorder them for merging.
Click the action button and let your browser do the work locally.
Download the resulting PDF. Nothing was ever uploaded.
No fixed limit. You can merge as many PDFs as your device's memory can handle — a hundred-page combined document is fine on a typical laptop. Very large jobs (hundreds of megabytes of source files) may take a minute or two.
Mild compression keeps scanned text perfectly readable. Heavy compression softens images, so if the document must be printed or archived long-term, use a gentler setting and keep the original. For email and web uploads, stronger compression is usually fine.
Yes — splitting and page extraction are fully supported. Use the Split tab to break a PDF into individual pages or custom ranges, and the Extract tab to pull out specific pages. JPG-to-PDF conversion is also available: upload your images and download a combined PDF in seconds.
Not yet — password-protecting PDFs is on the roadmap. The current toolkit covers merging, compressing, splitting, extracting pages, and converting JPG images to PDF, which handles the most common everyday requests.
No. Both merging and compression run entirely in your browser via pdf-lib. Your contracts, IDs, and financial documents never leave your device, which is exactly why a local tool is the right choice for sensitive paperwork.
Merging preserves each source file's embedded fonts and images, so the result is roughly the sum of its parts. If the merged file is too big for your email or form, run it through the Compress tab afterwards — the two tools are designed to be used in sequence.