Annotate a screenshot online, free — no watermark, no sign-up, nothing uploaded.
You took a screenshot. Now it needs an arrow, a box round the button, a line of text saying "click here". Arrowbox does all of that in one pass, in your browser. Press Win+Shift+S to grab the screen, open the page, press Ctrl+V. The screenshot is on the board and every tool is ready. No account, no upload, no watermark.
The toolset covers the usual jobs: arrows with eight head and tail styles, callouts with elbow leaders, text boxes that fit themselves to the text, rectangles, ellipses, a highlighter, and numbered step stamps that renumber themselves when you rearrange them. If the screenshot shows something private, redact it — pixelate, blur or solid black, destroyed for real on export.
One board holds several screenshots, so a before-and-after or a three-step walkthrough goes out as a single export. Done? Export PNG, JPEG or PDF, or hit Copy to put the flattened result straight on your clipboard. An untouched image exports at its exact original size. Nothing leaves your machine at any point — zero network calls after the page loads.
Open Arrowbox — free, no sign-upRuns in your browser. Nothing is uploaded — zero network calls, enforced by the page’s Content-Security-Policy. Desktop browsers work best.
How it works
- Capture the screenPress Win+Shift+S and drag across the region you need. Windows puts the capture on your clipboard — no need to save a file first.
- Paste into ArrowboxOpen arrowbox.app and press Ctrl+V. The screenshot appears on the board. Paste again, drag files in, or use Open to put several screenshots on the same board.
- Pick a tool and mark it upArrows for pointing, callouts for labelled leaders, text boxes for notes, the highlighter for emphasis, numbered stamps for step-by-step guides, rectangles and ellipses for boxing things in. Step numbers renumber automatically; text boxes fit themselves to what you type.
- Redact anything sensitivePixelate, blur or black out emails, names and keys. On export those pixels are genuinely destroyed in the output — there is no hidden layer to recover.
- Export or copyExport as PNG, JPEG or PDF — no watermark on any of them — or press Copy to put the flattened image on your clipboard, ready to paste into an email or a ticket.
Why Arrowbox
- Nothing is uploaded. The page makes zero network calls after it loads — enforced by an automated build gate, not a promise.
- No sign-up, no watermark, no telemetry. Open the page, paste, work.
- Every annotation job in one pass: arrows, callouts, text, highlights, shapes, numbered steps, redaction.
- Several screenshots compose on one board — a whole walkthrough goes out as one export.
- Exports are clean PNG, JPEG or PDF; an untouched image keeps its exact original size.
- Free, donation-supported, made by one developer.
Questions
Can I annotate a screenshot online without a watermark?
No watermark, ever. Arrowbox is free and donation-supported, so there is no paid tier to push you towards. PNG, JPEG and PDF exports come out clean, and the Copy button puts an equally clean flattened image on your clipboard.
Is my screenshot uploaded when I annotate it?
No. Arrowbox runs entirely in your browser and makes zero network calls after the page loads — the page's own security policy blocks them, and an automated build gate enforces that on every release. Your screenshot never leaves your machine.
Can I mark up several screenshots at once?
Yes. Paste, drag-drop or open as many images as you need onto one board. That suits multi-step walkthroughs: number each stage with the step stamps and export the whole board as a single PNG, JPEG or PDF — or export just a selection.
Do I need to install anything to mark up a screenshot?
No install, no extension, no account — it is one self-contained HTML page. It even works offline: press Ctrl+S, choose "HTML only", and the saved file runs from a USB stick or an air-gapped machine. Desktop browsers first; Chrome or Edge are best. Mobile is not good yet.