Key terms and concepts for screenshot APIs, headless browsers, and web capture technology.
A unique identifier used to authenticate and authorize access to an API. API keys are typically passed as query parameters or headers with each request, allowing the service to track usage and enforce rate limits.
api_key parameter. Get yours free from the dashboard. Keys are scoped per user and can be rotated anytime.AV1 Image File Format — a modern, royalty-free image format based on the AV1 video codec. AVIF offers 50% better compression than JPEG and 20% better than WebP at similar visual quality, making it ideal for web performance.
format=avif to get screenshots in AVIF format. Excellent for bandwidth-constrained applications — our AVIF screenshots are typically 60-70% smaller than PNG.The open-source browser engine that powers Google Chrome, Microsoft Edge, Brave, and many other browsers. Chromium provides the rendering engine used by most headless browser tools for accurate web page capture.
A UI overlay displayed on websites to comply with privacy regulations like GDPR and ePrivacy Directive. These banners ask visitors to accept or reject tracking cookies and often obstruct the page content underneath.
block_cookie_banners=true to automatically dismiss or hide cookie consent overlays before capturing. Works with all major consent management platforms (OneTrust, Cookiebot, etc.).The ability to inject custom CSS stylesheets into a web page before rendering. This allows hiding elements, changing layouts, adjusting fonts, or modifying any visual aspect of the page without modifying the source.
css parameter. Commonly used to hide navigation bars, ads, chat widgets, or style the page specifically for screenshots.Simulating how a website appears on different devices by configuring viewport dimensions, user agent string, device pixel ratio, and touch capabilities. Used to test responsive designs and capture mobile screenshots.
device parameter, or set custom width, height, and device_scale_factor values.The ratio between physical display pixels and CSS logical pixels. A DPR of 2 (common on Retina displays) means each CSS pixel is rendered using 2×2 physical pixels, resulting in sharper images at higher file sizes.
device_scale_factor=2 for Retina-quality captures. A 1280×800 viewport at DPR 2 produces a 2560×1600 pixel image. Default is 1.A programming interface that represents an HTML document as a tree of objects. The DOM allows scripts to dynamically read, modify, add, or delete elements and content on a web page. Modern SPAs heavily rely on DOM manipulation.
wait_until=domcontentloaded or networkidle to control when the DOM is considered ready.A capture of the entire scrollable content of a web page, from top to bottom, rather than just the visible viewport area. The resulting image can be very tall for content-rich pages with extensive scrolling.
full_page=true to capture the complete page. Useful for archiving, documentation, and visual testing. Combine with AVIF format to keep file sizes manageable.A web browser without a visible user interface, designed to be controlled programmatically. Headless browsers execute JavaScript, render CSS, handle network requests, and produce output identical to a regular browser — but run in the background without displaying anything on screen.
Executing custom JavaScript code on a web page before or after it loads. Used to manipulate page content, trigger interactions, remove elements, or extract data that requires client-side computation.
js parameter to run scripts before capture. Example: scroll to a section, click a button, expand collapsed content, or remove a modal overlay.Meta tags in a page's <head> that control how URLs appear when shared on social media (Facebook, Twitter, LinkedIn, Slack, etc.). Key tags include og:title, og:description, og:image, and og:url.
Converting web pages or HTML content into PDF documents. Browser-based PDF generation respects CSS print stylesheets, page breaks, and layout, producing high-fidelity results compared to template-based PDF tools.
format=pdf with options for paper size (pdf_format), margins (pdf_margin), and pdf_print_background. Supports A4, Letter, Legal, and custom sizes.A cross-browser automation framework by Microsoft for end-to-end testing and web scraping. Supports Chromium, Firefox, and WebKit with a single API. Known for auto-waiting, reliable selectors, and parallel execution.
A Node.js library developed by Google's Chrome team that provides a high-level API to control Chrome/Chromium. Widely used for screenshots, PDFs, web scraping, and automated testing. The most popular headless browser library.
A technique to control the number of API requests a client can make within a given time window. Prevents abuse, ensures fair usage, and protects server resources. Typically returns HTTP 429 when limits are exceeded.
X-RateLimit-Remaining so you can pace your requests.A web service that captures visual representations of web pages as images (PNG, JPEG, WebP, AVIF) or PDFs via simple HTTP API calls. Screenshot APIs abstract away the complexity of running headless browsers, handling JavaScript rendering, managing timeouts, and dealing with edge cases like cookie banners and lazy-loaded content.
A security vulnerability where an attacker tricks a server into making HTTP requests to unintended internal resources (like localhost, internal APIs, or cloud metadata endpoints). Particularly relevant for screenshot APIs that fetch arbitrary URLs.
The visible area of a web page within the browser window. The viewport dimensions determine how the page's responsive layout renders — a 375px viewport triggers mobile styles, while 1920px shows the full desktop layout.
width and height to define the viewport (default: 1280×800). Combine with device presets for accurate device emulation including user agent and DPR.A parameter that controls when a web page is considered "fully loaded" and ready for capture. Common strategies include waiting for DOM content loaded, all network requests to complete, or a specific element to appear.
load (default), domcontentloaded, networkidle (wait for network to be idle), or selector:.my-element (wait for a specific CSS selector).The automated extraction of data from websites using bots, scripts, or APIs. Modern web scraping often requires a headless browser to handle JavaScript-rendered content, SPAs, and dynamically loaded data.
An HTTP callback — a POST request sent automatically to a specified URL when an event occurs. Webhooks enable real-time notifications without polling, commonly used for async processing results and integration triggers.
An image format developed by Google that provides both lossy and lossless compression. WebP images are typically 25-34% smaller than JPEG at equivalent visual quality, with broad browser support (95%+ globally).
format=webp for a great balance of quality and file size. WebP is our recommended format for most use cases — it's well-supported and significantly smaller than PNG/JPEG.