Turn the pages that came in sideways, and keep them turned.

Turn a whole file.

Open the PDF merger and add the file. Each file's row has a turn button: every press turns all its pages a quarter clockwise, and the picture of its first page shows the result. Press Merge PDF with that one file in the list and download it. The turn is written into each page, so every reader shows it the right way up.

A page that already had a turn keeps it, and the one you chose is added to it.

• Open Rotate PDF
• Open the PDF merger

Turn only some pages.

Switch from the list of files to the Pages view. Every page is a small picture. Click a page, Shift-click to take everything up to another, or Select all, then use the toolbar to turn the selection either way. On a keyboard, R turns a quarter clockwise and Shift+R the other way. Every turn can be undone.

The PDF editor does the same. Open Pages in its bar, choose the pages, and turn them. Anything you added to a page stays where it is on what the page shows.

• Guide: rearrange, add and insert pages

The merger or the editor?

Both copy pages as they are: text stays text and pictures are not compressed again. The merger is quickest for a whole file or several files at once. The editor keeps more of a file's structure: accessibility tags, which the merger does not carry over, stay with their pages. Use the editor for a tagged report, or when you are changing other things in it anyway.

A digital signature does not survive either way. Turning a page changes the file, and a signature covers the file as it was signed.

• Open the PDF editor

Look before you save.

After Merge PDF, Read it here opens the merged file itself in a large reader, so you can page through and see every page the right way up before you download it. If one is still wrong, turn it in the Pages view and merge again; the result says when it is out of date.

Turning a page changes which way it is shown, not its size. A landscape table in a portrait report stays a landscape page, now readable without tipping your head. To print everything on one size of paper, the merger's printing options can fit every page to A4 or Letter, and a wide page then gets the sheet on its side.

Photos that are not a PDF yet.

If the pages start as photos, turn them before they become a PDF. The PDF maker reads which way up each photo was taken, shows it upright, and turns any page with a button or the R key.

• Guide: many pictures, one tidy PDF

Your file stays with you.

The file is opened, turned and written in your browser. Nothing is uploaded, and once the page has loaded it works without a connection.