# How NotchStar detects what you copy > NotchStar checks the Mac clipboard about every half second. When its change counter moves, it reads the new item and adds it to history locally. Canonical: https://www.notchstar.com/help/how-notchstar-detects-clipboard-copies/ Last updated: 2026-11-04 Published 2026-11-04. NotchStar finds out about your copies by asking the Mac's clipboard whether it changed, about every half second. The clipboard keeps a change counter that goes up each time anything is copied. When NotchStar sees the counter move, it reads what is on the clipboard and adds it to the list. ## What happens on each check 1. NotchStar compares the counter with the last one it saw. If it is the same, it stops there and costs almost nothing. 2. If a password manager marked the copy as concealed, it stops and records nothing. 3. If the copy holds files from Finder, it records the files. 4. Otherwise, if there is text, it records the text. 5. Otherwise, if there is an image, it records a reduced copy of the image. That order is why a Finder copy shows up as a file and a spreadsheet copy shows up as text. See [images](https://www.notchstar.com/help/clipboard-history-images-notchstar/) and [files](https://www.notchstar.com/help/clipboard-history-files-copied-in-finder/). ## It keeps checking with the notch closed The check runs while NotchStar is running, whether the notch is open or closed. That is how it can show a copy you made a minute ago when you open Clipboard. ## Why polling The Mac does not tell apps when the clipboard changes, so a half second check is the usual way clipboard tools work. Two copies within half a second of each other can mean only the last one is seen. ## Limits Copies made before NotchStar started are not read. See [that page](https://www.notchstar.com/help/clipboard-copied-before-notchstar-started/). The tool is on the [Clipboard feature page](https://www.notchstar.com/features/clipboard/). ## Quick answers. ### How often does NotchStar check the clipboard? About every half second, by comparing the clipboard change counter. ## Keep reading. - [Clipboard history that lives in your notch](https://www.notchstar.com/features/clipboard/): Searchable clipboard history in the Mac notch: text, links, images and files. Skips password manager copies. Click any item to copy it again. - [Why NotchStar missed a copy made before it started](https://www.notchstar.com/help/clipboard-copied-before-notchstar-started/): NotchStar only records copies made while it runs. What was on the clipboard at launch, or copied while it was closed, is not added. - [Does NotchStar clipboard history need any permission](https://www.notchstar.com/help/clipboard-permissions-notchstar/): NotchStar's Clipboard tool requests no Accessibility, Screen Recording or other permission in its code. It reads the Mac clipboard and keeps history in memory. - [What is clipboard history?](https://www.notchstar.com/glossary/clipboard-history/): Clipboard history is a list of the things you recently copied, so you can paste an older item again. Learn how it works on a Mac and what to watch for. ## More in Clipboard. - [How to search your clipboard history in NotchStar](https://www.notchstar.com/help/search-your-clipboard-history/): Open the notch, pick Clipboard and type to filter 50 recent copies. Search ignores capitals and accents, and typing image finds copied images. - [How many items NotchStar clipboard history keeps](https://www.notchstar.com/help/clipboard-history-limit-50-items/): NotchStar keeps the 50 most recent clipboard items, at most 10 of them images. Older items drop off, and the list shows the 30 newest matches at a time. - [Why your NotchStar clipboard history clears when you quit](https://www.notchstar.com/help/clipboard-history-clears-on-quit/): NotchStar keeps clipboard history in memory only, so quitting the app clears it. Nothing is written to disk, and password manager copies are skipped. - [How to paste an older item from NotchStar clipboard history](https://www.notchstar.com/help/paste-from-notchstar-clipboard-history/): Open the notch, pick Clipboard, click the item you want, then press Command V where you want it. NotchStar copies the item back and does not paste for you. - [What happens when you copy the same thing twice in NotchStar](https://www.notchstar.com/help/copy-again-moves-clipboard-item-to-top/): Copy the same text, image or file again and NotchStar moves it to the top of the clipboard list instead of adding a duplicate. Here is how it matches. - [What NotchStar does with files you copy in Finder](https://www.notchstar.com/help/clipboard-history-files-copied-in-finder/): NotchStar records files copied in Finder as files, with their icon, not as text names. Click a row to copy the file again. Search matches name and path.