For one arrow on a screenshot, use what took the screenshot: Snipping Tool on Windows, Markup on a Mac or an iPhone. Free, no account, and the marks save into the file. For an image several people have to discuss, a mockup, a chart, a bug screenshot, a proof, the file is the wrong container, because a PNG cannot hold a reply. Upload the image behind a link with an annotation layer instead, so every comment and its answer stay pinned to the pixel they are about.
Windows: Snipping Tool. Press Win + Shift + S, take the capture, click the notification, and the editor opens with a pen, a highlighter, shapes, a text tool, a ruler and an eraser (Microsoft's guide). Save or copy. On raw speed nothing beats it.
macOS: Markup. After a screenshot, click the thumbnail in the corner before it fades and Markup opens on it directly. For a file already saved, open it in Preview and click the Markup button: pen, shapes, text, highlighter, colour picker.
iPhone and iPad: Markup. Tap the screenshot preview and the same pen and shape tools appear, with the bonus that a full-page web screenshot can be captured and marked up in one pass.
Free, no account, and all three write the marks into the image.
The output of every tool above is a PNG, and a PNG has no idea it is part of a conversation.
Replies detach: your arrow points at a button, their answer is a chat message somewhere below the image. Versions fork: they annotate your annotated screenshot and send it back, so now there are two and one of them is stale. Nothing is pinned, so "the spacing under the header" means re-finding the spot every time someone reads the thread. Two rounds in, the image in the thread and the image somebody is looking at are not the same image.
For one arrow sent once, none of that matters. For a design review, a bug report, a proof or a client sign-off, all of it does.
Each mark records where it sat on the image rather than where it sat on your screen, so it stays on the right pixel when the window changes size or the link is opened on a different display.
| What you're doing | Use |
|---|---|
| One arrow on a screenshot, sent once | Snipping Tool or Markup. Fastest, and it saves to the file |
| An image you need as a flattened file | Snipping Tool, Markup or Preview, same reason |
| A mockup or proof someone has to sign off on | A link-based annotator, so approval and questions stay on the image |
| A bug screenshot a developer will ask about | A link, so the follow-up question lands on the pixel |
| A chart or diagram a group is discussing | A link, so replies thread instead of scattering through chat |
No annotated image comes out, because the marks live in the link and not in the file.
No text highlights on an image, since there is no text layer to bind one to. A PDF with real text behaves differently, which is covered in how to annotate a PDF.
The element inspector, measure and multi-select are hidden, because they read a page's HTML and an image has none.
Uploads cap at 25MB, and the file is deleted 90 days after the last time the link was opened.
Annotating is desktop only. Opening a shared link to read works anywhere.
Paste any URL at marklayer.app and annotate the live page in your browser. No install, no account, no sign-up. Recipients of your share links don't need to install anything either.
Annotate a page