Show HN: Free tool to mark points and polygon regions

# tack. — Mark coordinates on images Source: [https://tack.pics/](https://tack.pics/) Mark · Trace · Export ## tack\.it down\. A precision tool for marking points and polygon regions on images\. Free, runs entirely in your browser — your images never leave your device\. JSON / YAML exportBezier polygonsCustom origin / unitsWorks offline \(PWA\) About tack\. ## Pin coordinates onto any image — drop in, click out, copy the data\. tack\. is built for game developers, level designers, UI engineers, ML data labelers, and anyone who needs to translate a picture into a structured set of coordinates\. Drop in an image, click to drop points, drag to draw bezier curves, and export clean JSON or YAML you can paste straight into your code\. Choose where the origin sits — top\-left for screen space, bottom\-left for math space, or center for symmetric layouts\. Flip the Y\-axis if you're working with math coordinates\. Switch to normalized 0–1 output if you need resolution\-independent data\. Features ## Built for precision work\. ### Points & polygons Drop single points, draw open polylines, or close shapes into polygons\. Mix all three on the same image\. ### Bezier curves Click\-and\-drag to add smooth anchors with handles\. Break symmetry with Alt; re\-sync with Shift\. ### Multiple origins Top\-left, top\-right, bottom\-left, bottom\-right, center, or any custom point you click\. ### Pixel or normalized Switch between absolute pixels and 0\-1 normalized coordinates with one toggle\. ### Y\-axis flip Match screen\-space \(Y down\) or math\-space \(Y up\) without re\-mapping anything yourself\. ### Round\-trip JSON Load existing JSON back into the tool to edit it\. No re\-tracing from scratch\. ### Undo / redo 100 steps of history\. Cmd\+Z and Cmd\+Shift\+Z, exactly as you'd expect\. ### Keyboard nudging Arrow keys nudge selected anchors by 1 pixel\. Hold Shift for 10\-pixel jumps\. ### Works offline Install as a PWA\. The app runs without a network connection once visited\. Use cases ## What people use Tack for\. - 2D game collision boundaries - Hit zones for click / tap targets - Pathing waypoints for AI - Spawn points and triggers - Hotspots for interactive maps - Annotation regions for ML datasets - Image\-based UI layout coordinates - Sprite anchor points - Region\-of\-interest extraction - Floorplan / blueprint markup Privacy ## Your images never leave your device\. Tack runs entirely in your browser\. The image you load, the points you draw, the JSON you export — none of it is uploaded anywhere\. There is no server\-side processing, no account, no login\. We only collect anonymous, cookie\-less page\-view analytics so we know the site is reaching people\. Read the[privacy statement](https://tack.pics/privacy/)and[terms of service](https://tack.pics/terms/)\.