An office asks for your form, your ID and two certificates. The upload box takes one file. You have five photos and a scan. This is the shortest way through.
The order matters. Each step undoes some of the work of the step before it, so doing them backwards means doing them twice.
A photo taken with a phone often arrives sideways or upside down on a computer, even though it looked fine on the phone. If you turn it into a PDF while it is sideways, every page comes out sideways too.
Fix it first with Rotate & Flip. You can do all the photos in one go. If a page is a few degrees crooked because you photographed it lying on a table, the fine angle slider straightens it.
A PDF is a document. A photo is a picture. You cannot merge them directly — the photos have to become PDF pages first.
Use JPG to PDF. Pick the photos, put them in order, and you get one PDF holding all of them.
One thing worth setting here: choose A4 rather than fit-to-photo if the pages will be printed. Otherwise every page comes out a different size and the printed result looks untidy.
Now everything is a PDF, so it can be joined. Use Merge PDF, add the files, and put them in the order the office asked for.
Order sounds unimportant but it is the thing people most often get wrong. If the letter says "form, then ID, then certificates", send it in that order. Someone has to read it, and a jumbled file makes their job harder.
If you only need part of a file — say pages 1 to 3 of a long scan — you can type that next to the file instead of merging the whole thing.
Check the size. If it is under the limit, you are done. Do not compress a file that does not need it — you only lose quality for nothing.
If it is too heavy, the reason is almost always the photos, not the PDF. Scanned pages are full photographs, and ten of them add up fast.
The most reliable fix is to go back and shrink the photos before step two, using the Image Compressor, then build the PDF again. That sounds like extra work, but it gives a much better result than squeezing a finished PDF.
This costs five seconds and it matters more than people think. A file called IMG_20260830_114523.pdf tells the person nothing. Application_Kaur_Kitchen_Assistant.pdf tells them everything.
Use your surname and what the file is about. Avoid spaces if the portal is old — underscores are safer. And keep the ending as .pdf.
Open the finished PDF and scroll through every page. Not the first page — every page. Look for pages that are upside down, pages that are missing, and pages that got included twice.
This takes a minute and it is the difference between a file that gets accepted and a letter three weeks later asking you to send it again.
The documents people merge are usually private: contracts, pay slips, certificates, medical letters. Most online tools upload your file to a server to do the work. The tools here do it inside your browser instead, so nothing is uploaded and no copy is kept anywhere.