No cropping
The editor keeps the size of the image you bring. Crop when you take the screenshot: Win + Shift + S lets you drag over just the region you need.
Free tool · in your browser
Annotate a screenshot online.
Paste a screenshot with Ctrl + V, drop the file or open an image, then mark it with an arrow, rectangle, highlighter, text or step numbers. Add a background and shadow, then copy or download the PNG. Nothing is uploaded: it all happens in your browser.
Sincron Screen ToolsScreenshot editor · runs in your browser
Opening the editor…
On Windows, this is one key.
CtrlShiftD draws arrows, boxes and text over any app
CtrlShiftC crops and adds background, padding and shadow
Free tool · in your browser
How do you annotate a screenshot online?
Open the screenshot in an editor that runs in the browser, like the one above: paste it with Ctrl + V (Cmd + V on a Mac), drop the file or click Open image. Pick the arrow, rectangle, highlighter or text tool and drag over the spot you want to mark. Then copy the result or download it as a PNG.
Everything happens inside your browser tab. The image is not sent to a server, so you can mark up screenshots with internal data without uploading them anywhere. Closing the tab discards the image and the marks.
If you annotate screenshots every day on Windows, the Sincron Screen Tools app does the same without a browser: Ctrl + Shift + D draws over any program and Ctrl + Shift + C captures the screen and opens the Screenshot Studio.
Reviewed on October 3, 2026
Step by step
How to annotate a screenshot in 4 steps
The editor at the top of this page works in any current browser, on a computer or a phone.
Bring the screenshot in
Take the screenshot — Win + Shift + S on Windows, Cmd + Ctrl + Shift + 4 on a Mac — and press Ctrl + V on this page. You can also drop the file onto the editor or click Open image. PNG, JPG, WebP and GIF work.
Mark what matters
An arrow to point, a rectangle or ellipse to frame, the highlighter to emphasize a line, text for a short note and numbers for a sequence of steps. Hold Shift for straight lines and perfect squares; Ctrl + Z undoes the last mark.
Hide what should not go
Cover passwords, emails and names with the Hide tool. It draws an opaque box that becomes part of the exported PNG, so the original pixels are gone from the file.
Frame it and send it
Turn on the frame for a gradient or solid background, padding, rounded corners and a shadow. Copy image puts the PNG on the clipboard, ready to paste into Slack, Teams, email or a ticket; Download PNG saves the file.
On Windows
On Windows, it's one key
The online editor is for the occasional screenshot. When marking up screenshots is part of your day, the extra steps add up: take the screenshot, open this page, paste, mark, copy.
Sincron Screen Tools for Windows 10 and 11 skips them. Ctrl + Shift + D draws arrows, rectangles, highlights and text over any program, on every monitor, while the program underneath keeps working; the draw toolbar captures the area or the full screen with the drawings. Ctrl + Shift + C crops a region and opens the Screenshot Studio, with background, padding, corners and shadow, then copy the image or save the PNG.
Capturing, annotating and drawing in the app are free, with no limits. They work without internet, and the screenshot never leaves your PC unless you send it.
Comparison
Online editor or the Windows app?
Both are free for annotating. The difference is where you start and what each one can do.
| Feature | Online editor (this page) | Sincron Screen Tools for Windows |
|---|---|---|
| How you start | Take the screenshot, then paste or drop it here | Ctrl + Shift + D draws on the live screen; Ctrl + Shift + C captures |
| Arrow, rectangle, ellipse, highlighter, text | Yes | Yes, over any program, captured with the drawings |
| Step numbers | Yes | No |
| Solid box to hide data | Yes | No |
| Background, padding, corners, shadow | Yes | Yes, in the Screenshot Studio, plus aspect ratio and position |
| Where it runs | Any current browser, including Mac and phones | Windows 10 and 11 |
| Price | Free | Capture, annotate and draw free with no limits; paid plans from US$ 36/year |
Facts about the app checked against version 0.8.1 on October 3, 2026.
Real limits
What the online editor does not do
No blur or pixelation
To hide data, use the solid box. A blur looks softer, but a light one can sometimes be read or partly reversed; an opaque box replaces the pixels.
Marks can't be moved
Each mark is final once drawn. Use Ctrl + Z to undo it and draw it again in the right place.
Nothing is kept for later
There is no account or history. Reloading or closing the tab discards the image and the marks, so download the PNG if you will need it again.
Copy depends on the browser
Some browsers block writing images to the clipboard. When that happens the editor tells you, and Download PNG always works.
Very large images are reduced
Images above roughly 16 megapixels or 8,192 pixels on a side are scaled down to fit what a browser canvas can handle.
Questions about annotating screenshots online
How do you annotate a screenshot?
Open the screenshot in an editor, pick a tool — arrow, rectangle, highlighter or text — and drag over the image. On this page you paste with Ctrl + V, mark the image and copy or download the PNG. On Windows, Sincron Screen Tools draws over any program with Ctrl + Shift + D.
Is this screenshot editor free?
Yes. The online editor is free, needs no account, adds no watermark and has no limit on how many images you edit.
Are my images uploaded?
No. The image is opened and edited inside your browser tab, and the PNG is generated there too. Nothing is sent to a server, and closing the tab discards it.
How do I add an arrow to a screenshot online?
Paste or open the screenshot, choose the Arrow tool (shortcut A) and drag from where the arrow starts to the point it should touch. Hold Shift to keep it at 45° steps, and press R, O, Y, G or B to change its color.
Does it work on a phone or a Mac?
Yes. It runs in any current browser. On a phone, tap Open image to pick a screenshot and draw with your finger. The Sincron Screen Tools app, on the other hand, is only for Windows 10 and 11.
How do I hide a password or an email in a screenshot?
Choose the Hide tool (shortcut X) and drag over the text. It draws an opaque box that is merged into the exported PNG, so the hidden text is not in the file.
See also
Annotate screenshots on Windows
Arrows, highlights and text on a screenshot, with background and shadow. Free and unlimited.
Screenshot background on Windows
The Sincron Screenshot Studio: background, padding, corners and shadow for Windows screenshots.
How to annotate a screenshot
Three ways to mark up a screenshot on Windows 11: Snipping Tool, Paint and Sincron.
Annotating every day? Make it one key.
Install Sincron Screen Tools for Windows: Ctrl + Shift + D draws arrows and boxes over any program, and Ctrl + Shift + C captures and frames the screenshot. Capturing, annotating and drawing are free, with no limits.