# ScreenSnapShot — Full Technical Reference > ScreenSnapShot is a Chrome extension that captures full-page scrolling screenshots with one click. All processing happens locally in the browser — no uploads, no accounts, no tracking. Website: https://screensnapshot.t10.net Privacy Policy: https://screensnapshot.t10.net/privacy.html Contact: https://screensnapshot.t10.net/contact.html --- ## Overview ScreenSnapShot is a Chrome Manifest V3 extension built with vanilla JavaScript and zero external dependencies. It provides full-page scrolling screenshot capture, clipboard copy, PNG/PDF export, and a built-in image editor. All image processing occurs entirely within the browser — no data is ever uploaded to any server. --- ## How the Capture Process Works 1. **Initiate**: The user clicks the ScreenSnapShot extension icon in the Chrome toolbar. 2. **Inject content script**: The extension injects a small script into the active tab using the `scripting` permission. This script measures the total page height and width. 3. **Scroll loop**: The extension scrolls the page from top to bottom, capturing each viewport using `chrome.tabs.captureVisibleTab()`. After the first viewport, fixed/sticky elements (navigation bars, headers) are temporarily hidden to prevent them from repeating in every captured frame. 4. **Overlap algorithm**: The final viewport may not be a full viewport height. The extension calculates the overlap and captures only the unique remaining portion, ensuring seamless stitching with no duplicated content. 5. **Stitch in offscreen canvas**: Chrome extension service workers cannot access the DOM or Canvas API. An offscreen document (via the `offscreen` permission) provides the Canvas API needed to stitch all captured viewport images into a single full-page screenshot. 6. **Export**: The stitched image is made available for clipboard copy, PNG download, PDF export, or editing in the built-in editor. All injected code is removed automatically after the capture completes. --- ## Features in Detail ### Full-Page Scrolling Capture (Free) Automatically scrolls through the entire webpage and captures every viewport. Works on pages of any length. The extension handles scroll position management, viewport capture timing, and image stitching automatically. ### Smart Fixed/Sticky Header Handling (Free) After the first viewport is captured, the extension detects and temporarily hides elements with `position: fixed` or `position: sticky` (such as navigation bars and cookie banners). This prevents these elements from repeating in every captured frame, producing a clean, seamless screenshot. ### Copy to Clipboard (Free) One-click copy of the full-page screenshot to the system clipboard. The image can be pasted directly into Slack, Figma, Google Docs, email clients, or any application that accepts pasted images. ### Save as PNG (Pro) Lossless image export at full resolution. The screenshot is saved via Chrome's standard Downloads API directly to the user's device. No data is uploaded anywhere. ### Save as PDF (Pro) Export the screenshot as a PDF document, suitable for printing, documentation, and archiving. The PDF is generated entirely in the browser using a hand-built PDF binary format: the canvas image is encoded as JPEG using DCTDecode and embedded in a minimal PDF structure. No external PDF libraries are used. ### Built-in Editor (Pro) A full image editor opens in a new tab with the following capabilities: - **Crop tool**: Select and crop any region of the screenshot - **Rectangle annotations**: Draw rectangles to highlight areas, with customizable colors and stroke widths - **Color picker**: Choose annotation colors from a palette or custom hex input - **Stroke width control**: Adjust annotation line thickness - **Zoom and pan**: Zoom in/out and pan across large screenshots - **Export**: Save the edited image as PNG or copy to clipboard ### Retina/HiDPI Support (Free) Captures at the device's actual pixel resolution (device pixel ratio). Screenshots taken on Retina or HiDPI displays are crisp and full-resolution. ### Privacy-First Architecture (Free) All screenshot capture, stitching, editing, and export happens 100% locally in the browser. No images are ever uploaded to any server. No analytics, telemetry, or tracking of any kind. No user accounts or personal data collected. No cookies set by the extension. --- ## Browser Permissions Explained ### Active Tab (`activeTab`) Allows the extension to access the content of the currently active tab, but only when the user explicitly clicks the extension icon. Used to measure page dimensions and capture the visible viewport. The extension cannot access tabs in the background. ### Scripting (`scripting`) When a capture is initiated, the extension injects a small script into the active tab to measure the total page height, scroll to each viewport position, and temporarily hide fixed/sticky elements. All injected code is removed after capture completes. ### Downloads (`downloads`) Used exclusively to save finished screenshots as PNG or PDF files to the user's computer via Chrome's standard download mechanism. Files are saved directly to the device — no data is uploaded. ### Offscreen (`offscreen`) Chrome extension service workers cannot access the DOM or Canvas API. This permission creates a hidden offscreen document that provides the Canvas API needed to stitch captured viewport images into a single full-page screenshot and to convert PNG images to PDF format. The offscreen document has no network access. ### Storage (`storage`) Used by ExtensionPay (the payment provider) to cache the user's purchase status locally in `chrome.storage.sync`. Stores only a simple paid/unpaid flag — no personal information, browsing data, or screenshots. --- ## Pricing ### Free Tier - Full-page scrolling screenshot capture - Smart fixed/sticky header hiding - Copy to clipboard - Retina/HiDPI support - 100% local processing ### Pro Tier (One-Time Payment) Everything in Free, plus: - Save as PNG — lossless full-resolution export - Save as PDF — for printing, documentation, and archiving - Built-in editor — crop, rectangle annotations, custom colors, stroke widths, zoom/pan **Pro is a one-time payment — not a subscription.** Pay once and use all Pro features forever, including future updates. Price: $5 Payments are processed securely by ExtensionPay (which uses Stripe). The extension never sees, processes, or stores credit card information. --- ## Target Audience - **Developers**: Capture full-page screenshots of web applications for documentation, bug reports, and QA - **Designers**: Screenshot entire page designs for review, comparison, and portfolio - **Content creators**: Capture articles, social media pages, and web content for reference - **QA testers**: Document visual bugs and page states across different viewports - **Documentation writers**: Generate full-page screenshots for guides, tutorials, and help articles --- ## Frequently Asked Questions **What is ScreenSnapShot?** ScreenSnapShot is a Chrome extension that captures full-page scrolling screenshots. It automatically scrolls through the entire page, captures each viewport, and stitches them together into a single seamless image. **Is ScreenSnapShot free?** Yes. The core features — capturing full-page screenshots and copying them to your clipboard — are completely free. Pro features like saving as PNG, saving as PDF, and the built-in editor are available with a one-time purchase. **What pages can it capture?** ScreenSnapShot works on any standard webpage in Chrome. Some browser-internal pages (like chrome:// URLs) are restricted by Chrome itself and cannot be captured by any extension. **Does it upload my screenshots anywhere?** No. All processing happens 100% locally in your browser. Your screenshots never leave your device. There are no servers, no cloud storage, and no data collection of any kind. **What's included in Pro?** Pro unlocks saving screenshots as PNG files, exporting to PDF, and a full built-in editor with crop, rectangle annotations, customizable colors and stroke widths, and zoom/pan controls. **Is Pro a subscription?** No. Pro is a one-time payment. Pay once and you have access to all Pro features forever, including future updates. --- ## Comparison: ScreenSnapShot vs Cloud-Based Screenshot Tools Unlike cloud-based screenshot services, ScreenSnapShot processes everything locally in your browser: - **No uploads**: Your screenshots never leave your device - **No accounts**: No sign-up, no login, no email required - **No tracking**: Zero analytics, telemetry, or data collection - **No latency**: Instant capture and export without waiting for server processing - **No privacy risk**: Sensitive page content (banking, medical, internal tools) stays on your machine - **Works offline**: After installation, no internet connection needed for capture and clipboard copy --- ## Technical Stack - Chrome Manifest V3 - Vanilla JavaScript — zero external runtime dependencies - Service Worker architecture - Offscreen Document for Canvas API access - Chrome Downloads API for file export - ExtensionPay / Stripe for payment processing - No external CDNs, no tracking scripts, no analytics