Sort the task into one of three kinds
Document needs fall into three groups: assembling and splitting (combining PDFs, pulling out pages), converting format or content (PDF to images, to text, tables to data), and adding something (signatures, watermarks, stamps). Classify first, then choose the tool — one tool per task is usually enough.
Merging and splitting: order and page ranges bite first
Confirm file order before merging, since most systems concatenate in upload order and getting it wrong means starting over. For splitting, check the page range (say pages 3–7) — a wrong range wastes the whole pass. PDFs with an open password or permission restrictions must be unlocked first or even the preview fails. Merging does not re-compress content: quality stays the same and the total size is roughly the sum of the parts.
Scanned files: image-only PDFs need OCR
People often ask why text extraction returns nothing when "the words are obviously there". Because a scan is a stack of images with no text layer. Test it quickly: try selecting text in the original — if it highlights, there is a text layer; if not, it is image-only and needs OCR. Accuracy depends on sharpness and skew, so rotate a crooked scan before recognising and the result improves a lot.
Data and format conversion: don’t lose information on the way
When exporting a spreadsheet to CSV with Chinese text, choose "CSV UTF-8" or the recipient sees mojibake. Fields containing commas or line breaks must be quoted; Excel does that for you, and it is the first thing to break when hand-building data. Converting between YAML and JSON: YAML 1.1 treats yes/no as booleans, so verify types against what the target expects, and note that comments and anchors are dropped — do not use it as an intermediate format if you need them. OFD is China’s fixed-layout standard (common on e-invoices) that ordinary readers cannot open; view and convert it to PDF or images right here.
Signatures and stamps: know the legal line
Pasting a handwritten signature image onto a PDF is a graphical signature: fine for internal routing, expense forms and informal confirmations. For contracts, property or employment, the law expects a reliable electronic signature with identity verification and tamper protection — a pasted image does not carry the same weight. Likewise the e-seal generator here is decorative and must not be used on real documents. The point of saying so is to save you trouble, not to upsell: use a compliant e-signature service for anything that matters.
What local processing means for documents
Contracts, invoices and medical reports are exactly the files people refuse to upload to a stranger’s server — a sensible instinct. Local processing means parsing and generation happen on your device: it works offline, nothing is uploaded and no copy is left behind. The trade-off is that very large files (hundreds of MB of drawings) need more memory, so handle those in batches on a desktop or with dedicated software.
FAQ
Can a scanned PDF be converted to text directly?
Only if it has a text layer. If you can select text in the original, extraction works; if not, it is image-only and needs OCR — and the result still deserves a human check on numbers and proper nouns.
Does merging reduce quality?
No. Merging concatenates content in order without re-compressing images; the file grows because every page keeps its original data.
Is there a file size limit?
Nothing imposed by a server, but your device memory is the limit. Ordinary documents of tens of MB are no problem; drawings of hundreds of MB are better handled on a desktop.