Combine readable, unencrypted PDF files in a chosen file order. Merging runs in your browser with pdf-lib; review the documented test and unsupported features before using the result.
Drop PDF files here or click to upload
Select multiple PDF files to merge • Files are processed locally
We generated three owned, unencrypted PDFs containing four visibly labeled pages with unique dimensions. The same pdf-lib 1.17.1 copyPages and addPage sequence used by this tool merged them into one file. We then reopened the saved result and checked the page count and ordered dimensions.
| Assertion | Expected | Observed | Result |
|---|---|---|---|
| Input files | 3 | 3 | pass |
| Output pages | 4 | 4 | pass |
| File-level page order and dimensions | A4 portrait → Letter portrait → Letter landscape → A5 portrait | Same ordered dimensions after reopening | pass |
Inspect the cover fixture, two-page report fixture, appendix fixture, and merged result. The raw JSON records sizes and SHA-256 hashes; rerun it with npm run benchmark:pdf.
This controlled test does not cover forms, digital signatures, bookmarks, attachments, encryption, malformed files, very large files, or every browser/device. Keep the originals and check the downloaded result before deleting or sharing anything.
Add two or more readable PDF files. The files will be merged in the order shown in the queue.
Use the up and down controls to reorder whole files before merging. The first file in the queue supplies the first pages.
Click Merge & Download, then open the result and check its page order. Mizakii does not receive the selected files, but the merged copy is saved through your browser's download handling.
Merging happens in the browser with pdf-lib, and Mizakii does not receive or store the PDFs you select. The page code and library still load through your network, and your browser, extensions, device, download folder, backups, and workplace policies remain part of the security boundary. Do not assume that any online page is automatically appropriate for medical records, identity documents, signed contracts, or other sensitive files.
Each selected file is parsed in sequence and its pages are copied into a new PDF document. The controls change whole-file order; they do not rearrange individual pages inside a source file.
This tool uses pdf-lib 1.17.1 in the browser. There is no application-level upload limit, but the browser must hold input and output data in memory. Large or complex batches can be slow or fail, especially on memory-constrained devices.
Pages are copied rather than intentionally rasterized, but a new PDF is still written. The controlled test above verifies only its stated properties. Features such as forms, signatures, bookmarks, attachments, and encryption need a specialist PDF tool and separate validation.
| Need | Current support | What to check |
|---|---|---|
| Combine ordinary, unencrypted PDFs | Supported | Open the output and verify every page. |
| Change whole-file order | Supported with up/down controls | Pages inside each file retain their source order. |
| Change individual page order | Not supported | Use a page-level PDF editor. |
| Encrypted or password-protected PDFs | Not supported | Do not upload passwords; use an authorized specialist workflow. |
| Preserve forms, signatures, bookmarks, or attachments | Not established | Use a tool that explicitly supports and validates the required feature. |
| Very large batches | Device-dependent | Try smaller groups and retain every original. |
Choose based on the document feature you must preserve, not on a blanket “free versus paid” claim. Keep the source files until the merged result has been opened and checked.
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