Tool facts
- Input and output
- application/pdf → application/pdf
- Files per operation
- 2–20
- Total input limit
- 100 MiB
- Page limit
- 100
- Processing
- In your browser; no file upload
- Account
- Not required
- Price
- Free
Scope of these facts
- Selected file contents stay in the browser for processing. Loading the website and its separate usage analytics can still use the network.
- Verification covers the declared checks for supported files, not independent certification or acceptance by another portal. A format-signature check is not digital-signature validation.
- JavaScript, the required browser APIs and sufficient device memory are needed. Limits are admission ceilings, not a guarantee for every file, browser or iPhone.
- Supported pages are combined without rasterization or image recompression. Not every document-level feature is preserved; an offered removal fallback requires review.
How it works
- Select at least two PDFs or drop them in the file area.
- Use the up and down buttons to arrange your PDFs. You can remove files or add more.
- Choose Merge PDF. Download becomes available only after the output passes verification.
Your order, every page
Files are combined from top to bottom in the list. The pages within each file keep their original order. The ordering buttons work with a mouse, touch or keyboard. We reparse the merged PDF and compare page content, resources, page boxes and rotation in that exact sequence.
Page quality and document features
Merging does not rasterize or recompress pages. Original page dimensions and remaining content are retained. If annotations, forms, bookmarks, accessibility tags or print color conditions prevent merging, you can explicitly agree to remove the listed features. Entered form values, visible marks, comments and links may be lost. Removing output intents can change colors; PDF/A and PDF/X conformance is not preserved. No pages are deleted. Encryption, signatures, unsafe structures and layers remain unsupported. Document-level metadata is not combined.
Private browser processing
File bytes stay on your device. Processing runs in a local browser Worker, without server uploads, accounts or file telemetry. Your originals are never overwritten. Changing the file list or order removes the previous download.
Limits and supported PDFs
Combine 2–20 PDFs, up to 100 MiB in total and 100 pages. There are additional object, graph-depth and 30-second processing limits. This version supports traditional PDF 1.0–1.7 cross-reference tables plus common compressed object/xref streams and incremental updates when they stay within bounded structural-decompression limits. Unsupported structural filters, encryption and digital signatures are declined. A browser Worker provides cancellation; it does not provide a hard browser memory quota.
Frequently asked questions
Can I merge PDFs on my phone?
Yes, in a current browser with Web Worker and local file support. Select files from your device and tap the arrow buttons to change their order. Smaller batches work better on devices with limited memory.
Will digital signatures stay valid?
No such guarantee is possible after combining documents. This tool declines signed PDFs rather than invalidating their signatures silently.
Why was a valid PDF declined?
A PDF can be valid and still use structures or features that cannot be verified or preserved within the safety limits, such as unsupported structural filters or oversized compressed structures. The error explains the limitation; a declined file is not modified.
Are different page sizes supported?
Yes. Each supported page keeps its own dimensions, page boxes and rotation; pages are not resized to match one another.